codes for staad pro india

STAAD.Pro 2007

INTERNATIONAL DESIGN CODES DAA037810-1/0001

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Indian Codes

9-1

Concrete Design Per IS456

9A.1 Design Operations

STAAD has the capabilities of performing concrete design based

on limit state method of IS: 456 (2000).

9A.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be

designed.

For Beams Prismatic (Rectangular & Square), T-Beams and

L-shapes

For Columns Prismatic (Rectangular, Square and Circular)

9A.3 Member Dimensions

Concrete members which will be designed by the program must

have certain section properties input under the MEMBER

PROPERTY command. The following example shows the required

input:

Section 9A


Section 9A9-2

UNIT MM

MEMBER PROPERTY

1 3 TO 7 9 PRISM YD 450. ZD 250.

11 13 PR YD 350.

14 TO 16 PRIS YD 400. ZD 750. YB 300. ZB 200.

will be done accordingly. In the above input, the first set of

members are rectangular (450 mm depth and 250mm width) and

the second set of members, with only depth and no width provided,

will be assumed to be circular with 350 mm diameter. The third set

numbers in the above example represen ts a T-shape with 750 mm

flange width, 200 width, 400 mm overall depth and 100 mm flange

depth (See section 6.20.2). The program will determine whether

the section is rectangular, flanged or circular and the beam or

column design

9A.4 Design Parameters

The program contains a number of parameters which are needed to

perform design as per IS:456(2000). Default parameter values

have been selected such that they are frequently used numbers for

conventional design requirements. These values may be changed to

suit the particular design being performed. Table 8A.1 of this

manual contains a complete list of the available parameters and

their default values. It is necessary to declare length and force

units as Millimeter and Newton before performing the concrete

design.

9A.5 Slenderness Effects and Analysis Consideration

Slenderness effects are extremely important in designing

compression members. The IS:456 code specifies two options by

which the slenderness effect can be accommodated (Clause 39.7).

Section 9A 9-3

One option is to perform an exact analysis which will take into

account the influence of axial loads and variable moment of inertia

on member stiffness and fixed end moments, the effect of

deflections on moment and forces and the effect of the duration of

loads. Another option is to approximately magnify design

moments.

STAAD has been written to allow the use of the first options. To

perform this type of analysis, use the command PDELTA

ANALYSIS instead of PERFORM ANALYSIS. The PDELTA

ANALYSIS will accommodate all requirements of the second-

order analysis described by IS:456, except for the effects of the

duration of the loads. It is felt that this effect may be safely

ignored because experts believe that the effects of the duration of

loads are negligible in a normal structural configuration.

Although ignoring load duration effects is somewhat of an

approximation, it must be realized that the approximate evaluation

of slenderness effects is also an approximate method. In this

method, additional moments are calculated based on empirical

formula and assumptions on sidesway

(Clause 39.7.1 and 39.7.1.1,IS: 456 - 2000).

Considering all these information, a PDELTA ANALYSIS, as

performed by STAAD may be used for the design of concrete

members. However the user must note, to take advantage of this

analysis, all the combinations of loading must be provided as

primary load cases and not as load combinations. This is due to the

fact that load combinations are just algebraic combinations of

forces and moments, whereas a primary load case is revised during

the P-delta analysis based on the deflections. Also note that the

proper factored loads (like 1.5 for dead load etc.) should be

provided by user. STAAD does not factor the loads automatically.

9A.6 Beam Design

Beams are designed for flexure, shear and torsion. If required the

effect the axial force may be taken into consideration. For all


Section 9A

9-4

these forces, all active beam loadings are prescanned to identify

the critical load cases at different sections of the beams. The total

number of sections considered is 13( e.g. 0.,.1,.2,.25,.3,.4,.5,.6,.7,.

75,.8,.9 and 1). All of these sections are scanned to determine the

design force envelopes.

Design for Flexure

Maximum sagging (creating tensile stress at the bottom face of the

beam) and hogging (creating tensile stress at the top face)

moments are calculated for all active load cases at each of the

above mentioned sections. Each of these sections is designed to

resist both of these critical sagging and hogging moments. Where

ever the rectangular section is inadequate as singly reinforced

section, doubly reinforced section is tried. However, presently the

flanged section is designed only as singly reinforced section under

sagging moment. It may also be noted all flanged sections are

automatically designed as rectangular section under hogging

moment as the flange of the beam is ineffective under hogging

moment. Flexural design of beams is performed in two passes. In

the first pass, effective depths of the sections are determined with

the assumption of single layer of assumed reinforcement and

reinforcement requirements are calculated. After the preliminary

design, reinforcing bars are chosen from the internal database in

single or multiple layers. The entire flexure design is per formed

again in a second pass taking into account of the changed effective

depths of sections calculated on the basis of reinforcement provide

after the preliminary design. Final provisions of flexural

reinforcements are made then. Efforts have been made to meet the

guideline for the curtailment of reinforcements as per IS:456-2000

(Clause 26.2.3). Although exact curtailment lengths are not

mentioned explicitly in the design output (finally which will be

more or less guided by the detailer taking into account of other

practical consideration), user has the choice of printing

reinforcements provided by STAAD at 11 equally spaced sections

from which the final detail drawing can be prepared.

Section 9A

9-5

Design for Shear

Shear reinforcement is calculated to resist both shear forces and

torsional moments. Shear design are performed at 11 equally

spaced sections (0.to 1.) for the maximum shear forces amongst

the active load cases and the associated torsional moments. Shear

capacity calculation at different sections with out the shear

reinforcement is based on the actual tensile reinforcement

provided by STAAD program. Two-legged stirrups are provided to

take care of the balance shear forces acting on these sections.

As per Clause 40.5 of IS:456-2000 shear strength of sections (< 2d

where d is the effective depth) close to support has been enhanced,

subjected to a maximum value of cmax.

Beam Design Output

The default design output of the beam contains flexural and shear

reinforcement provided at 5 equally spaced (0,.25,.5,.75 and 1.)

sections along the length of the beam. User has option to get a

more detail output. All beam design outputs are given in IS units.

An example of rectangular beam design output with the default

output option (TRACK 0.0) is presented below:


Section 9A

9-6

============================================================================ B E A M N O. 12 D E S I G N R E S U L T S M20 Fe415 (Main) Fe415 (Sec.) LENGTH: 4000.0 mm SIZE: 250.0 mm X 350.0 mm COVER: 30.0 mm DESIGN LOAD SUMMARY (KN MET) ---------------------------------------------------------------------------- SECTION |FLEXTURE (Maxm. Sagging/Hogging moments)| SHEAR (in mm) | P MZ MX Load Case | VY MX Load Case ---------------------------------------------------------------------------- 0.0 | 0.00 0.00 0.00 4 | 29.64 1.23 4

| 0.00 -25.68 1.23 4 | 400.0 | 0.00 0.00 0.00 4 | 27.97 1.23 4 | 0.00 -16.05 1.23 4 | 800.0 | 0.00 0.00 0.00 4 | 25.12 1.23 4 | 0.00 -7.17 1.23 4 | 1200.0 | 0.00 0.97 0.49 5 | 21.11 1.23 4

| 0.00 -0.14 1.32 6 | 1600.0 | 0.00 6.77 1.23 4 | 15.93 1.23 4 | 0.00 0.00 0.00 4 |

2000.0 | 0.00 11.06 1.23 4 | 9.59 1.23 4 | 0.00 0.00 0.00 4 | 2400.0 | 0.00 13.04 1.23 4 | 2.08 1.23 4

| 0.00 0.00 0.00 4 | 2800.0 | 0.00 12.45 1.23 4 | -5.43 1.23 4 | 0.00 0.00 0.00 4 | 3200.0 | 0.00 9.55 1.23 4 | -11.77 1.23 4 | 0.00 0.00 0.00 4 | 3600.0 | 0.00 4.73 1.23 4 | -16.95 1.23 4

| 0.00 0.00 0.00 4 | 4000.0 | 0.00 0.00 0.00 4 | -25.48 1.23 4 | 0.00 -17.36 1.23 4 | ----------------------------------------------------------------------------

SUMMARY OF REINF. AREA (Sq.mm) ---------------------------------------------------------------------------- SECTION 0.0 mm 1000.0 mm 2000.0 mm 3000.0 mm 4000.0 mm ----------------------------------------------------------------------------

TOP 259.04 161.29 0.00 0.00 176.31 REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

BOTTOM 0.00 160.78 160.78 160.78 0.00 REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) ----------------------------------------------------------------------------

SUMMARY OF PROVIDED REINF. AREA

---------------------------------------------------------------------------- SECTION 0.0 mm 1000.0 mm 2000.0 mm 3000.0 mm 4000.0 mm ---------------------------------------------------------------------------- TOP 4-10Ø 3-10Ø 2-10Ø 2-10Ø 3-10Ø REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

BOTTOM 2-12Ø 2-12Ø 2-12Ø 2-12Ø 2-12Ø REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

SHEAR 2 legged 8Ø 2 legged 8Ø 2 legged 8Ø 2 legged 8Ø 2 legged 8Ø REINF. @ 100 mm c/c @ 100 mm c/c @ 100 mm c/c @ 100 mm c/c @ 100 mm c/c

----------------------------------------------------------------------------

============================================================================

Section 9A

9-7

9A.7 Column Design

Columns are designed for axial forces and biaxial moments at the

ends. All active load cases are tested to calculate reinforcement.

The loading which yield maximum reinforcement is called the

critical load. Column design is done for square, rectangular and

circular sections. By default, square and rectangular columns and

designed with reinforcement distributed on each side equally for

the sections under biaxial moments and with reinforcement

distributed equally in two faces for sections under uniaxial

moment. User may change the default arrangement of the

reinforcement with the help of the parameter RFACE (see Table

8A.1). Depending upon the member lengths, section dimensions

and effective length coefficients specified by the user STAAD

automatically determine the criterion (short or long) of the column

design. All major criteria for selecting longitudinal and transverse

reinforcement as stipulated by IS:456 have been taken care of in

the column design of STAAD. Default clear spacing between main

reinforcing bars is taken to be 25 mm while arrangement of

longitudinal bars.

Column Design Output

Default column design output (TRACK 0.0) contains the

reinforcement provided by STAAD and the capacity of the section.

With the option TRACK 1.0, the output contains intermediate

results such as the design forces, effective length coefficients,

additional moments etc. A special output TRACK 9.0 is introduced

to obtain the details of section capacity calculations. All design

output is given in SI units. An example of a long column design

(Ref.Example9 of SP:16, Design Aids For Reinforced Concrete to

IS:456-1978) output (with option TRACK 1.0) is given below.


Section 9A

9-8

============================================================================ C O L U M N N O. 1 D E S I G N R E S U L T S M20 Fe415 (Main) Fe415 (Sec.)

LENGTH: 3000.0 mm CROSS SECTION: 250.0 mm dia. COVER: 40.0 mm ** GUIDING LOAD CASE: 5 BRACED LONG COLUMN

DESIGN FORCES (KNS-MET) ----------------------- DESIGN AXIAL FORCE (Pu) : 62.0

About Z About Y INITIAL MOMENTS : 2.21 32.29

MOMENTS DUE TO MINIMUM ECC. : 1.24 1.24 SLENDERNESS RATIOS : 12.00 12.00 MOMENTS DUE TO SLENDERNESS EFFECT : 1.12 1.12 MOMENT REDUCTION FACTORS : 1.00 1.00 ADDITION MOMENTS (Maz and May) : 1.12 1.12

TOTAL DESIGN MOMENTS : 3.32 33.40 REQD. STEEL AREA : 1822.71 Sq.mm. MAIN REINFORCEMENT : Provide 17 - 12 dia. (3.92%, 1922.65 Sq.mm.) (Equally distributed)

TIE REINFORCEMENT : Provide 8 mm dia. rectangular ties @ 190 mm c/c SECTION CAPACITY (KNS-MET) --------------------------

Puz : 992.70 Muz1 : 36.87 Muy1 : 36.87

INTERACTION RATIO: 1.00 (as per Cl. 38.6, IS456)

============================================================================

Section 9A

9-9

Table 9A.1 Indian Concrete Design IS456 Parameters

Parameter Default Description Name Value

FYMAIN 415 N/mm2 Yield Stress for main reinforcing steel.

FYSEC 415 N/mm2 Yield Stress for secondary reinforcing steel.

FC 30 N/mm2 Concrete Yield Stress.

CLEAR 25 mm 40 mm

For beam members. For column members

MINMAIN 10 mm Minimum main reinforcement bar size.

MAXMAIN 60 mm Maximum main reinforcement bar size.

MINSEC 8 mm Minimum secondary reinforcement bar size.

MAXSEC 12 mm Maximum secondary reinforcement bar size.

BRACING 0.0 BEAM DESIGN

A value of 1.0 means the effect of axial force will be taken into account for beam design.

COLUMN DESIGN

A value of 1.0 means the column is unbraced about major axis.

A value of 2.0 means the column is unbraced about minor axis.

A value of 3.0 means the column is unbraced about both axis.

RATIO 4.0 Maximum percentage of longitudinal reinforcement in columns.


Section 9A

9-10



RFACE 4.0 A value of 4.0 means longitudinal reinforcement in column is arranged equally along 4 faces.

A value of 2.0 invokes 2 faced distribution about major axis.

A value of 3.0 invokes 2 faced distribution about minor axis.

WIDTH ZD Width to be used for design. This value defaults to ZD as provided under MEMBER PROPERTIES.

DEPTH YD Total depth to be used for design. This value defaults to YD as provided under MEMBER PROPERTIES.

TRACK 0.0 BEAM DESIGN:

For TRACK = 0.0, output consists of reinforcement details at START, MIDDLE and END. For TRACK = 1.0, critical moments are printed in addition to TRACK 0.0 output. For TRACK = 2.0, required steel for intermediate sections defined by NSECTION are printed in addition to TRACK 1.0 output.

COLUMN DESIGN:

With TRACK = 0.0, reinforcement details are printed. With TRACK = 1.0, column interaction analysis results are printed in addition to TRACK 0.0 output. With TRACK = 2.0, a schematic interaction diagram and intermediate interaction values are printed in addition to TRACK 1.0 output.

With TRACK = 9.0, the details of section capacity calculations are printed.

REINF 0.0 Tied column. A value of 1.0 will mean spiral reinforcement.

Section 9A

9-11



ELZ 1.0 Ratio of effective length to actual length of column about major axis.

ELY 1.0 Ratio of effective length to actual length of column about minor axis.

ULY 1.0 Ratio of unsupported length to actual length of column about minor axis.

ULZ 1.0 Ratio of unsupported length to actual length of column about major axis.

TORSION 0.0 A value of 0.0 means torsion to be considered in beam design. A value of 1.0 means torsion to be neglected in beam design.

SPSMAIN 25 mm Minimum clear distance between main reinforcing bars in beam and column. For column centre to centre distance between main bars cannot exceed 300mm.

SFACE 0.0 Face of support location at start of beam. It is used to check against shear at the face of the support in beam design. The parameter can also be used to check against shear at any point from the start of the member.

EFACE 0.0 Face of support location at end of beam. The parameter can also be used to check against shear at any point from the end of the member. (Note: Both SFACE and EFACE are input as positive numbers).


Section 9A

9-12



ENSH 0.0 Perform shear check against enhanced shear strength as per Cl. 40.5 of IS456:2000. ENSH = 1.0 means ordinary shear check to be performed ( no enhancement of shear strength at sections close to support) For ENSH = a positive value(say x ), shear strength will be enhanced up to a distance x from the start of the member. This is used only when a span of a beam is subdivided into two or more parts. (Refer note ) For ENSH = a negative value(say –y), shear strength will be enhanced up to a distance y from the end of the member. This is used only when a span of a beam is subdivided into two or more parts.(Refer note) If default value (0.0) is used the program will calculate Length to Overall Depth ratio. If this ratio is greater than 2.5, shear strength will be enhanced at sections (<2d) close to support otherwise ordinary shear check will be performed.

RENSH 0.0 Distance of the start or end point of the member from its nearest support. This parameter is used only when a span of a beam is subdivided into two or more parts. (Refer note)

Bar combination has been introduced for detailing. Please refer section 8A.8 for details. Notes: Value of ENSH parameter (other than 0.0 and 1.0) is used only

when the span of a beam is subdivided into two or more parts. When this

condition is aroused RENSH parameter is also to be used.

Once a parameter is specified, its value stays at that specified

number till it is specified again. This is the way STAAD works for all

codes.

Section 9A

9-13

The span of the beam is subdivided four parts, each of length L

metre. The shear strength will be enhanced up to X metre from

both supports. The input should be the following:

Steps:

ENSH L MEMB 1 => Shear strength will be enhanced

throughout the length of the member 1,

positive sign indicates length

measured from start of the member

ENSH (X-L) MEMB 2 => Shear strength will be enhanced up to

a length (X-L) of the member 2, length

measured from the start of the member

ENSH –L MEMB 4 => Shear strength will be enhanced

throughout the length of the member 4,

negative sign indicates length

measured from end of the member

ENSH –(X-L) MEMB 3 => Shear strength will be enhanced up to

a length (X-L) of the member 3, length

measured from the end of the member

RENSH L MEMB 2 3 => Nearest support lies at a distance L

from both the members 2 and 3.

DESIGN BEAM 1 TO 4=> This will enhance the shear strength

up to length X from both ends of the

beam consisting of members 1 to 4 and

gives spacing accordingly.


Section 9A

9-14

At section = y1 from start of member 1 av = y1

At section = y2 from the start of member 2 av = y2+L

At section = y3 from the end of member 3 av = y3+L

At section = y4 from end of member 4 av = y4

where c, enhanced = 2dc/av

At section 0.0, av becomes zero. Thus enhanced shear strength will

become infinity. However for any section shear stress cannot

exceed c, max. Hence enhanced shear strength is limited to a

maximum value of c, max.

9A.8 Bar Combination

Initially the program selects only one bar to calculate the number

of bars required and area of steel provided at each section along

the length of the beam. Now, two bar diameters can be specified to

calculate a combination of each bar to be provided at each section.

The syntax for bar combination is given below.

START BAR COMBINATION

MD1 <bar diameter> MEMB <member list>

MD2 <bar diameter> MEMB <member list>

END BAR COMBINATION

Section 9A

9-15

MD2 bar diameter should be greater than MD1 bar diameter. The typical output for bar combination is shown below:

OUTPUT FOR BAR COMBINATION

--------------------------------------------------------------

| M A I N R E I N F O R C E M E N T |

--------------------------------------------------------------

SECTION | 0.0- 2166.7 | 2166.7- 6500.0 | 6500.0- 8666.7 |

| mm | mm | mm |

--------------------------------------------------------------

TOP | 6-20í + 1-25í| 2-20í + 1-25í | 2-20í |

| in 2 layer(s)| in 1 layer(s) | in 1 layer(s) |

Ast Reqd| 2330.22 | 1029.90 | 582.55 |

Prov| 2376.79 | 1119.64 | 628.57 |

Ld (mm) | 940.2 | 940.2 | 940.2 |

--------------------------------------------------------------

BOTTOM | 4-20í | 2-20í | 2-20í |

|in 1 layer(s) | in 1 layer(s) | in 1 layer(s) |

Ast Reqd| 1165.11 | 582.55 | 582.55 |

Prov| 1257.14 | 628.57 | 628.57 |

Ld (mm) | 940.2 | 940.2 | 940.2 |

-------------------------------------------------------------

The beam length is divided into three parts, two at its ends and one at span. Ld gives the development length to be provided at the two ends of each section.

9A.9 Wall Design in accordance with IS 456-2000

Design of walls in accordance with IS 456-2000 is available in

STAAD.Pro.

Design is performed for in-plane shear, in-plane and out-of-plane

bending and out-of-plane shear. The wall has to be modeled using

STAAD‟s Surface elements. The use of the Surface element

enables the designer to treat the entire wall as one entity. It greatly

simplifies the modeling of the wall and adds clarity to the analysis

and design output. The results are presented in the context of the

entire wall rather than individual finite elements thereby allowing

users to quickly locate required information.


Section 9A

9-16

The program reports shear wall design results for each load

case/combination for user specified number of sections given by

SURFACE DIVISION (default value is 10) command. The shear

wall is designed at these horizontal sections. The output includes

the required horizontal and vertical distributed reinforcing, the

concentrated (in-plane bending) edge reinforcing and the link

required for out-of-plane shear.

General format:

START SHEARWALL DESIGN

CODE INDIAN

FYMAIN f1

FC f2

HMIN f3

HMAX f4

VMIN f5

VMAX f6

EMIN f7

EMAX f8

LMIN f9 LMAX f10

CLEAR f11

TWOLAYERED f12

KSLENDER f13

DESIGN SHEARWALL LIST shearwall-list

END

Section 9A

9-17

The following table explains the parameters used in the shear wall

design. Note: Once a parameter is specified, its value stays at

that specified number till it is specified again. This is the way

STAAD works for all codes.

SHEAR WALL DESIGN PARAMETERS

Parameter Name Default

Value

Description

FYMAIN 415 Mpa Yield strength of steel, in current units.

FC 30 Mpa Compressive strength of concrete, in current units.

HMIN 8 Minimum size of horizontal reinforcing bars (range 6 mm – 36 mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.

HMAX 36 Maximum size of horizontal reinforcing bars (range 6 mm – 36 mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.

VMIN 8 Minimum size of vertical reinforcing bars (range 6mm – 36mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.

VMAX 36 Maximum size of vertical reinforcing bars (range 6mm – 36mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.

EMIN 8 Minimum size of vertical reinforcing bars located in edge zones (range 6mm – 36mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.

EMAX 36 Maximum size of vertical reinforcing bars located in edge zones (range 6mm – 36mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.

LMIN 6 Minimum size of links (range 6mm – 16mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.


Section 9A

9-18

SHEAR WALL DESIGN PARAMETERS

Parameter Name Default

Value

Description

LMAX 16 Maximum size of links (range 6mm – 16mm). If input is 6 (integer number) the program will assume 6 mm diameter bar.

CLEAR 25 mm Clear concrete cover, in current units. TWOLAYERED 0 Reinforcement placement mode:

0 - single layer, each direction 1 - two layers, each direction

KSLENDER 1.0 Slenderness factor for finding effective height. Table 6

The following example illustrates the input for the definition of

shear wall and design of the wall.

Example

.

.

SET DIVISION 12

SURFACE INCIDENCES

2 5 37 34 SUR 1

19 16 65 68 SUR 2

11 15 186 165 SUR 3

10 6 138 159 SUR 4

.

.

.

SURFACE PROPERTY

1 TO 4 THI 18

SUPPORTS

1 7 14 20 PINNED

2 TO 5 GEN PIN

6 TO 10 GEN PIN

Section 9A

9-19

11 TO 15 GEN PIN

19 TO 16 GEN PIN

.

.

.

SURFACE CONSTANTS

E 2.17185e+007

POISSON 0.17

DENSITY 23.5616

ALPHA 1e-005

.

.

START SHEARWALL DES

CODE INDIAN

UNIT NEW MMS

FC 25

FYMAIN 415

TWO 1

VMIN 12

HMIN 12

EMIN 12

DESIGN SHEA LIST 1 TO 4

END

Notes

1. Command SET DIVISION 12 indicates that the surface

boundary node-to-node segments will be subdivided into 12

fragments prior to finite element mesh generation.

2. Four surfaces are defined by the SURFACE INCIDENCES

command.

3. The SUPPORTS command includes the new support

generation routine. For instance, the line 2 TO 5 GEN PIN

assigns pinned supports to all nodes between nodes 2 and 5.

As the node-to-node distances were previously subdivided

by the SET DIVISION 12 command, there will be an


Section 9A

9-20

additional 11 nodes between nodes 2 and 5. As a result, all

13 nodes will be assigned pinned supports. Please note that

the additional 11 nodes are not individually accessible to the

user. They are created by the program to enable the finite

element mesh generation and to allow application of

boundary constraints.

4. Surface thickness and material constants are specified by the

SURFACE PROPERTY and SURFACE CONSTANTS,

respectively.

5. The shear wall design commands are listed between lines

START SHEARWALL DES and END. The CODE

command selects the design code that will be the basis for

the design. For Indian code the parameter is INDIAN. The

DESIGN SHEARWALL LIST command is followed by a

list of previously defined Surface elements intended as shear

walls and/or shear wall components.

Technical Overview

The program implements provisions of section 32 of IS 456-2000

and relevant provisions as referenced therein, for all active load

cases. The following steps are performed for each of the horizontal

sections of the wall.

Checking of slenderness limit

The slenderness checking is done as per clause no. 32.2.3. The

default effective height is the height of the wall. User can change

the effective height. The limit for slenderness is taken as 30.

Design for in-plane bending and vertical load (denoted by Mz

& Fy in the shear wall force output)

Walls when subjected to combined in-plane horizontal and vertical

forces produce in-plane bending in conjunction with vertical load.

According to clause no. 32.3.1, in-plane bending may be neglected

in case a horizontal cross section of the wall is always under

compression due combined effect of horizontal and vertical loads.

Otherwise, the section is checked for combined vertical load and

Section 9A

9-21

in-plane moment as column with axial load and uni-axial bending.

For this purpose, the depth is taken as 0.8 x horizontal length of

wall and breadth is the thickness of the wall. The reinforcement is

concentrated at both ends (edges) of the wall. The edge

reinforcement is assumed to be distributed over a len gth of 0.2

times horizontal length on each side. Minimum reinforcements are

according to clause no. 32.5.(a). Maximum 4% reinforcement is

allowed.

Design for in-plane shear (denoted by Fxy in the shear wall

force output)

By default, the program does not design only at the critical section

but at all the horizontal sections. By suitable use of the surface

division command, design at critical section as per clause no.

32.4.1 can be performed.

The design for in-plane shear is done as per clause no. 32.4. The

nominal shear stress is calculated as per clause no. 32.4.2 and it is

checked with the maximum allowable shear stress as per clause no.

32.4.2.1. The design shear strength of concrete is calculated as per

clause no. 32.4.3. Design of shear reinforcement is done as per

clause no. 32.4.4. Minimum reinforcements are as per clause no.

32.5.

Design for vertical load and out-of-plane vertical bending

(denoted by Fy and My respectively in the shear wall force

output)

Apart from the in-plane bending and horizontal shear force, the

wall is also subjected to out-of-plane bending in the vertical and

horizontal directions. The part of the wall which is not having

edge reinforcements (i.e. a zone of depth 0.6 x Length of the wall),

is designed again as column under axial load (i.e. vertical load)

and out-of-plane vertical bending. The minimum reinforcements

and maximum allowable spacings of reinforcements are as per

clause no. 32.5


Section 9A

9-22

Design for out-of-plane horizontal bending (denoted by Mx in

the shear wall force output)

The horizontal reinforcement which is already provided for in -

plane shear is checked against out-of-plane horizontal bending.

The wall is assumed as a slab for this purpose.

Design for out-of-plane shears (denoted by Qx and Qy in the

shear wall force output)

The out-of-plane shear arises from out-of-plane loading. The

nominal shear stresses are calculated as per clause no. 40.1.

Maximum allowable shear stresses are as per table 20. For shear

force in the vertical direction, shear strength of concrete section is

calculated as per section 4.1 of SP 16 : 1980 considering vertical

reinforcement as tension reinforcement. Similarly, for shear force

in the horizontal direction, shear strength of concrete section is

calculated considering horizontal reinforcement as tension

reinforcement. Shear reinforcements in the form of links are

computed as per the provisions of clause no. 40.4.

Shear Wall Design With Opening

The Surface element has been enhanced to allow design of shear

walls with rectangular openings. The automatic meshing algorithm

has been improved to allow variable divisions along wall and

opening(s) edges. Design and output are available for user selected

locations.

Description

Shear walls modeled in STAAD.Pro may include an unlimited

number of openings. Due to the presence of openings, the wall

may comprise up with different wall panels.

Section 9A

9-23

1. Shear wall set-up

Definition of a shear wall starts with a specification of the surface

element perimeter nodes, meshing divisions along node-to-node

segments, opening(s) corner coordinates, and meshing divisions of

four edges of the opening(s).

SURFACE INCIDENCE n1, ..., ni SURFACE s DIVISION sd1, ...,

sdj -

RECOPENING x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4 DIVISION

od1, ..., odk

where,

n1, ..., ni - node numbers on the perimeter of the shear wall,

s - surface ordinal number,

sd1, ..., sdj - number of divisions for each of the node-to-node distance on the surface perimeter,

x1 y1 z1 (...) - coordinates of the corners of the opening,

od1, ..., odk - divisions along edges of the opening.

Note:

If the sd1, ..., sdj or the od1, ..., odk list does not include all node-

to-node segments, or if any of the numbers listed equals zero, then

the corresponding division number is set to the default value (=10,

or as previously input by the SET DIVISION command).

Default locations for stress/force output, design, and design output

are set as follows:

SURFACE DIVISION X xd

SURFACE DIVISION Y yd


Section 9A

9-24

where,

xd - number of divisions along X axis,

yd - number of divisions along Y axis.

Note:

xd and yd represent default numbers of divisions for each edge of

the surface where output is requested. The output is provided for

sections located between division segments. For example, if the

number of divisions = 2, then the output will be produced for only

one section (at the center of the edge).

2. Stress/force output printing

Values of internal forces may be printed out for any user -defined

section of the wall. The general format of the command is as

follows:

PRINT SURFACE FORCE (ALONG ) (AT a) (BETWEEN d1, d2)

LIST s1, ...,si

where,

- local axis of the surface element (X or Y),

a - distance along the axis from start of the member

to the full cross-section of the wall,

d1, d2 - coordinates in the direction orthogonal to ,

delineating a fragment of the full cross-section for

which the output is desired. **

s1, ...,si - list of surfaces for output generation

** The range currently is taken in terms of local axis. If the local

axis is directed away from the surface, the negative range is to be

entered.

Section 9A

9-25

Note:

If command ALONG is omitted, direction Y (default) is assumed.

If command AT is omitted, output is provided for all sections

along the specified (or default) edge. Number of sections will be

determined from the SURFACE DIVISION X or SURFACE

DIVISION Y input values. If the BETWEEN command is

omitted, the output is generated based on full cross-section width.

3. Definition of wall panels

Input syntax for panel definition is as follows:

START PANEL DEFINITION

SURFACE i PANEL j ptype x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4

END PANEL DEFINITION

where,

i - ordinal surface number,

j - ordinal panel number,

ptype - panel type, one of: WALL, COLUMN, BEAM

x1 y1 z1 (...) - coordinates of the corners of the panel,

4. Shear wall design

The program implements different provisions of design of walls as

per code BS 8110. General syntax of the design command is as

follows:

START SHEARWALL DESIGN

(...)

DESIGN SHEARWALL (AT c) LIST s

END SHEARWALL DESIGN


Section 9A

9-26

Note:

If the command AT is omitted, the design proceeds for all cross

sections of the wall or panels, as applicable, defined by the

SURFACE DIVISION X or SURFACE DIVISION Y input

values.

a. No panel definition.

Design is performed for the specified horizontal full cross-section,

located at a distance c from the origin of the local coordinates

system. If opening is found then reinforcement is provided along

sides of openings. The area of horizontal and vertical bars

provided along edges of openings is equal to that of the respective

interrupted bars.

b. Panels have been defined.

Only wall panel design is supported in Indian code.

9-27


9A1.1 Design Operations

Earthquake motion often induces force large enough to cause

inelastic deformations in the structure. If the structure is brittle,

sudden failure could occur. But if the structure is made to behave

ductile, it will be able to sustain the earthquake effects better with

some deflection larger than the yield deflection by absorption of

energy. Therefore ductility is also required as an essential element

for safety from sudden collapse during severe shocks.

STAAD has the capabilities of performing concrete design as per

IS 13920. While designing it satisfies all provisions of IS 456 –

2000 and IS 13920 for beams and columns.

9A1.2 Section Types for Concrete Design

The following types of cross sections for concrete members can be

designed.

For Beams Prismatic (Rectangular & Square) & T-shape

For Columns Prismatic (Rectangular, Square and Circular)

Section 9A1


Section 9A1

9-28

9A1.3 Design Parameters

The program contains a number of parameters that are needed to

perform design as per IS 13920. It accepts all parameters that are

needed to perform design as per IS:456. Over and above it has

some other parameters that are required only when designed is

performed as per IS:13920. Default parameter values have been

selected such that they are frequently used numbers for

conventional design requirements. These values may be changed to

suit the particular design being performed. Table 8A1.1 of this

manual contains a complete list of the available parameters and

their default values. It is necessary to declare length and force

units as Millimeter and Newton before performing the concrete

design.

9A1.4 Beam Design

Beams are designed for flexure, shear and torsion. If required the

effect of the axial force may be taken into consideration. For all

these forces, all active beam loadings are prescanned to identify

the critical load cases at different sections of the beams. The total

number of sections considered is 13. All of these sections are

scanned to determine the design force envelopes.

For design to be performed as per IS:13920 the width of the

member shall not be less than 200mm(Clause 6.1.3). Also the

member shall preferably have a width-to depth ratio of more than

0.3 (Clause 6.1.2).

The factored axial stress on the member should not exceed 0.1fck

(Clause 6.1.1) for all active load cases. If it exceeds allowable

axial stress no design will be performed.

Section 9A1

9-29

Design for Flexure

Design procedure is same as that for IS 456. However while

designing following criteria are satisfied as per IS-13920:

1. The minimum grade of concrete shall preferably be M20. (Clause

5.2)

2. Steel reinforcements of grade Fe415 or less only shall be used.

(Clause 5.3)

3. The minimum tension steel ratio on any face, at any section, is

given by

min = 0.24fck/fy (Clause 6.2.1b)

The maximum steel ratio on any face, at any section, is given by max = 0.025 (Clause 6.2.2)

4. The positive steel ratio at a joint face must be at least equal to half

the negative steel at that face. (Clause 6.2.3)

5. The steel provided at each of the top and bottom face, at any

section, shall at least be equal to one-fourth of the maximum

negative moment steel provided at the face of either joint. (Clause

6.2.4)

Design for Shear

The shear force to be resisted by vertical hoops is guided by the

Clause 6.3.3 of IS 13920:1993 revision. Elastic sagging and

hogging moments of resistance of the beam section at ends are

considered while calculating shear force. Plastic sagging and

hogging moments of resistance can also be considered for shear

design if PLASTIC parameter is mentioned in the input file. (Refer

Table 8A1.1)

Shear reinforcement is calculated to resist both shear forces and

torsional moments. Procedure is same as that of IS 456.


Section 9A1

9-30

The following criteria are satisfied while performing design for

shear as per Cl. 6.3.5 of IS-13920:

The spacing of vertical hoops over a length of 2d at either end of

the beam shall not exceed

a) d/4

b) 8 times the diameter of the longitudinal bars

In no case this spacing is less than 100 mm.

The spacing calculated from above, if less than that calculated

from IS 456 consideration is provided.

Beam Design Output

The default design output of the beam contains flexural and shear

reinforcement provided at 5 equally spaced sections along the

length of the beam. User has option to get a more detail output. All

beam design outputs are given in IS units. An example of

rectangular beam design output with the default output option

(TRACK 1.0) is presented below:

Section 9A1

9-31 ============================================================================

B E A M N O. 11 D E S I G N R E S U L T S

M20 Fe415 (Main) Fe415 (Sec.)

LENGTH: 3500.0 mm SIZE: 250.0 mm X 350.0 mm COVER: 30.0 mm

DESIGN LOAD SUMMARY (KN MET)

----------------------------------------------------------------------------

SECTION |FLEXTURE (Maxm. Sagging/Hogging moments)| SHEAR

(in mm) | P MZ MX Load Case | VY MX Load Case

----------------------------------------------------------------------------

0.0 | 0.00 0.00 0.00 4 | 17.67 0.00 4

| 0.00 -2.74 0.00 5 |

291.7 | 0.00 1.15 0.00 5 | 16.26 0.00 4

| 0.00 0.00 0.00 4 |

583.3 | 0.00 4.61 0.00 5 | 13.97 0.00 4

| 0.00 0.00 0.00 4 |

875.0 | 0.00 7.44 0.00 5 | 10.78 0.00 4

| 0.00 0.00 0.00 4 |

1166.7 | 0.00 9.41 0.00 5 | 6.69 0.00 4

| 0.00 0.00 0.00 4 |

1458.3 | 0.00 10.33 0.00 5 | 1.10 0.00 5

| 0.00 0.00 0.00 4 |

1750.0 | 0.00 9.98 0.00 5 | -3.60 0.00 5

| 0.00 0.00 0.00 4 |

2041.7 | 0.00 8.23 0.00 5 | -10.02 0.00 4

| 0.00 0.00 0.00 4 |

2333.3 | 0.00 5.21 0.00 5 | -15.00 0.00 4

| 0.00 0.00 0.00 4 |

2625.0 | 0.00 1.14 0.00 5 | -19.08 0.00 4

| 0.00 0.00 0.00 4 |

2916.7 | 0.00 0.00 0.00 4 | -22.27 0.00 4

| 0.00 -3.79 0.00 5 |

3208.3 | 0.00 0.00 0.00 4 | -24.57 0.00 4

| 0.00 -9.35 0.00 5 |

3500.0 | 0.00 0.00 0.00 4 | -25.97 0.00 4

| 0.00 -15.34 0.00 5 |

*** DESIGN SHEAR FORCE AT SECTION 0.0 IS 68.60 KN.

- CLAUSE 6.3.3 OF IS-

13920

*** DESIGN SHEAR FORCE AT SECTION 3500.0 IS 75.24 KN.

- CLAUSE 6.3.3 OF IS-

13920

----------------------------------------------------------------------------

SUMMARY OF REINF. AREA (Sq.mm)

----------------------------------------------------------------------------

SECTION 0.0 mm 875.0 mm 1750.0 mm 2625.0 mm 3500.0 mm

----------------------------------------------------------------------------

TOP 226.30 0.00 0.00 0.00 226.30

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

BOTTOM 0.00 203.02 203.02 203.02 0.00

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

----------------------------------------------------------------------------

SUMMARY OF PROVIDED REINF. AREA

----------------------------------------------------------------------------

SECTION 0.0 mm 875.0 mm 1750.0 mm 2625.0 mm 3500.0 mm

----------------------------------------------------------------------------

TOP 3-10í 2-10í 2-10í 2-10í 3-10í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

BOTTOM 2-12í 2-12í 2-12í 2-12í 2-12í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

SHEAR 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í

REINF. @ 100 mm c/c @ 150 mm c/c @ 150 mm c/c @ 150 mm c/c @ 100 mm c/c

----------------------------------------------------------------------------

============================================================================


Section 9A1

9-32

9A1.5 Column Design

Columns are designed for axial forces and biaxial moments per IS

456:2000. Columns are also designed for shear forces as per

Clause 7.3.4. All major criteria for selecting longitudinal and

transverse reinforcement as stipulated by IS:456 have been taken

care of in the column design of STAAD. However following

clauses have been satisfied to incorporate provisions of IS 13920:

1. The minimum grade of concrete shall preferably be M20.

(Clause 5.2)

2. Steel reinforcements of grade Fe415 or less only shall be used.

(Clause 5.3)

3. The minimum dimension of column member shall not be less

than 200 mm. For columns having unsupported length

exceeding 4m, the shortest dimension of column shall not be

less than 300 mm. (Clause 7.1.2)

4. The ratio of the shortest cross-sectional dimension to the

perpendicular dimension shall preferably be not less than 0.4.

(Clause 7.1.3)

5. The spacing of hoops shall not exceed half the least lateral

dimension of the column, except where special confining

reinforcement is provided. (Clause 7.3.3)

6. Special confining reinforcement shall be provided over a

length lo from each joint face, towards mid span, and on either

side of any section, where flexural yielding may occur. The

length lo shall not be less than a) larger lateral dimension of

the member at the section where yielding occurs, b) 1/6 of

clear span of the member, and c) 450 mm. (Clause 7.4.1)

7. The spacing of hoops used as special confining reinforcement

shall not exceed ¼ of minimum member dimension but need

not be less than 75 mm nor more than 100 mm. (Clause 7.4.6)

Section 9A1

9-33

8. The area of cross-section of hoops provided are checked

against the provisions for minimum area of cross-section of

the bar forming rectangular, circular or spiral hoops, to be

used as special confining reinforcement. (Clause 7.4.7 and

7.4.8)

Column Design Output

Default column design output (TRACK 0.0) contains the

reinforcement provided by STAAD and the capacity of the section.

With the option TRACK 1.0, the output contains intermediate

results such as the design forces, effective length coefficients,

additional moments etc. A special output TRACK 9.0 is introduced

to obtain the details of section capacity calculations. All design

output is given in SI units. An example of a column design output

(with option TRACK 1.0) is given below. ============================================================================

C O L U M N N O. 3 D E S I G N R E S U L T S


LENGTH: 3000.0 mm CROSS SECTION: 350.0 mm X 400.0 mm COVER: 40.0 mm

** GUIDING LOAD CASE: 5 END JOINT: 2 SHORT COLUMN

DESIGN FORCES (KNS-MET)

-----------------------

DESIGN AXIAL FORCE (Pu) : 226.7

About Z About Y

INITIAL MOMENTS : 0.64 146.28

MOMENTS DUE TO MINIMUM ECC. : 4.53 4.53

SLENDERNESS RATIOS : - -

MOMENTS DUE TO SLENDERNESS EFFECT : - -

MOMENT REDUCTION FACTORS : - -

ADDITION MOMENTS (Maz and May) : - -

TOTAL DESIGN MOMENTS : 4.53 146.28

** GUIDING LOAD CASE: 5

Along Z Along Y

DESIGN SHEAR FORCES : 43.31 76.08

REQD. STEEL AREA : 3313.56 Sq.mm.

MAIN REINFORCEMENT : Provide 12 - 20 dia. (2.69%, 3769.91 Sq.mm.)

(Equally distributed)

CONFINING REINFORCEMENT : Provide 10 mm dia. rectangular ties @ 85 mm c/c

over a length 500.0 mm from each joint face towards

midspan as per Cl. 7.4.6 of IS-13920.

TIE REINFORCEMENT : Provide 10 mm dia. rectangular ties @ 175 mm c/c

SECTION CAPACITY (KNS-MET)

--------------------------

Puz : 2261.52 Muz1 : 178.71 Muy1 : 150.75

INTERACTION RATIO: 1.00 (as per Cl. 39.6, IS456:2000)

============================================================================

********************END OF COLUMN DESIGN RESULTS********************


Section 9A1

9-34

Note: Once a parameter is specified, its value stays at that

specified number till it is specified again. This is the way


Table 9A1.1 Indian Concrete Design IS13920 Parameters

Parameter

Name

Default Value Description

FYMAIN 415 N/mm2 Yield Stress for main reinforcing steel.

FYSEC 415 N/mm2 Yield Stress for secondary reinforcing steel.

FC 30 N/mm2 Concrete Yield Stress.

CLEAR 25 mm

40 mm

For beam members.

For column members

MINMAIN 10 mm Minimum main reinforcement bar size.

MAXMAIN 60 mm Maximum main reinforcement bar size.

MINSEC 8 mm Minimum secondary reinforcement bar size.

MAXSEC 12 mm Maximum secondary reinforcement bar size.

BRACING 0.0 BEAM DESIGN

A value of 1.0 means the effect of axial force will be taken into account for beam design.

COLUMN DESIGN

A value of 1.0 means the column is unbraced about major axis.

A value of 2.0 means the column is unbraced about minor axis.

A value of 3.0 means the column is unbraced about both axis.

RATIO 4.0 Maximum percentage of longitudinal reinforcement in columns.

RFACE 4.0 A value of 4.0 means longitudinal reinforcement in column is arranged equally along 4 faces.

A value of 2.0 invokes 2 faced distribution about major axis.

Section 9A1

9-35


Parameter

Name


A value of 3.0 invokes 2 faced distribution about minor axis.

WIDTH ZD Width to be used for design. This value defaults to ZD as provided under MEMBER PROPERTIES.

DEPTH YD Total depth to be used for design. This value defaults to YD as provided under MEMBER PROPERTIES.

ELZ 1.0 Ratio of effective length to actual length of column about major axis.

ELY 1.0 Ratio of effective length to actual length of column about minor axis.

REINF 0.0 Tied column. A value of 1.0 will mean spiral reinforcement.

TORSION 0.0 A value of 0.0 means torsion to be considered in beam design.

A value of 1.0 means torsion to be neglected in beam design.

TRACK 0.0 BEAM DESIGN:

For TRACK = 0.0, output consists of reinforcement details at START, MIDDLE and END.

For TRACK = 1.0, critical moments are printed in addition to TRACK 0.0 output.

For TRACK = 2.0, required steel for intermediate sections defined by NSECTION are printed in addition to TRACK 1.0 output.

COLUMN DESIGN:

With TRACK = 0.0, reinforcement details are printed.

With TRACK = 1.0, column interaction analysis results are printed in addition to TRACK 0.0 output.


Section 9A1

9-36


Parameter

Name


With TRACK = 2.0, a schematic interaction diagram and intermediate interaction values are printed in addition to TRACK 1.0 output.

SPSMAIN 25 mm Minimum clear distance between main reinforcing bars in beam and column. For column centre to centre distance between main bars cannot exceed 300mm.

SFACE 0.0 Face of support location at start of beam. It is used to check against shear at the face of the support in beam design. The parameter can also be used to check against shear at any point from the start of the member.*

EFACE 0.0 Face of support location at end of beam. The parameter can also be used to check against shear at any point from the end of the member. (Note: Both SFACE and EFACE are input as positive numbers).*

ENSH 0.0 Perform shear check against enhanced shear strength as per Cl. 40.5 of IS456:2000.

ENSH = 1.0 means ordinary shear check to be performed ( no enhancement of shear strength at sections close to support)

For ENSH = a positive value(say x ), shear strength will be enhanced up to a distance x from the start of the member. This is used only when a span of a beam is subdivided into two or more parts. (Refer note after Table 8A.1 )

For ENSH = a negative value(say –y), shear strength will be enhanced up to a distance y from the end of the member. This is used only when a span of a beam is subdivided into two or more parts.(Refer note after Table 8A.1)

If default value (0.0) is used the program will calculate Length to Overall Depth ratio. If this ratio is greater than 2.5, shear strength will be enhanced at sections (<2d) close to support otherwise ordinary shear check will

Section 9A1

9-37


Parameter

Name


be performed.

RENSH 0.0 Distance of the start or end point of the member from its nearest support. This parameter is used only when a span of a beam is subdivided into two or more parts. (Refer note after Table 8A.1)

EUDL None Equivalent u.d.l on span of the beam. This load value must be the unfactored load on span. During design the load value is multiplied by a factor 1.2. If no u.d.l is defined factored shear force due to gravity load on span will be taken as zero. No elastic or plastic moment will be calculated. Shear design will be performed based on analysis result.(Refer note)

GLD None Gravity load number to be considered for calculating equivalent u.d.l on span of the beam, in case no EUDL is mentioned in the input. This loadcase can be any static loadcase containing MEMBER LOAD on the beam which includes UNI, CON, LIN and TRAP member loading. CMOM member loading is considered only when it is specified in local direction. FLOOR LOAD is also considered.

The load can be primary or combination load. For combination load only load numbers included in load combination is considered. The load factors are ignored. Internally the unfactored load is multiplied by a factor 1.2 during design.

If both EUDL and GLD parameters are mentioned in the input mentioned EUDL will be considered in design

Note :

No dynamic (Response spectrum, 1893, Time History) and moving load cases are considered.

CMOM member loading in global direction is


Section 9A1

9-38


Parameter

Name


not considered.

UMOM member loading is not considered.

PLASTIC 0.0 Default value calculates elastic hogging and sagging moments of resistance of beam at its ends.

A value of 1.0 means plastic hogging and sagging moments of resistance of beam to be calculated at its ends.

IPLM 0.0 Default value calculates elastic/plastic hogging and sagging moments of resistance of beam at its ends.

A value of 1.0 means calculation of elastic/plastic hogging and sagging moments of resistance of beam to be ignored at start node of beam. This implies no support exists at start node.

A value of -1.0 means calculation of elastic/plastic hogging and sagging moments of resistance of beam to be considered at start node of beam. . This implies support exists at start node.

A value of 2.0 means calculation of elastic/plastic hogging and sagging moments of resistance of beam to be ignored at end node of beam. This implies no support exists at end node.

A value of -2.0 means calculation of elastic/plastic hogging and sagging moments of resistance of beam to be considered at end node of beam. . This implies support exists at end node. **

IMB 0.0 Default value calculates elastic/plastic hogging and sagging moments of resistance of beam at its ends.

A value of 1.0 means calculation of

Section 9A1

9-39


Parameter

Name


elastic/plastic hogging and sagging moments of resistance of beam to be ignored at both ends of beam. This implies no support exist at either end of the member.

A value of -1.0 means calculation of elastic/plastic hogging and sagging moments of resistance of beam to be considered at both ends of beam. This implies support exist at both ends of the member.**

COMBINE 0.0 Default value means there will be no member combination.

A value of 1.0 means there will be no printout of sectional force and critical load for combined member in the output.

A value of 2.0 means there will be printout of sectional force for combined member in the output.

A value of 3.0 means there will be printout of both sectional force and critical load for combined member in the output. ***

HLINK Spacing of longitudinal bars measured to the

outer face

Longer dimension of the rectangular confining hoop measured to its outer face. It shall not exceed 300 mm as per Cl. 7.4.8. If hlink value as provided in the input file does not satisfy the clause the value will be internally assumed as the default one. This parameter is valid for rectangular column.

Bar combination has been introduced for detailing. Please refer section 8A1.6 for details.

* EFACE and SFACE command is not valid for member combination. ** IPLM and IMB commands are not valid for member combination. These commands are ignored for members forming physical member.


Section 9A1

9-40

*** The purpose of COMBINE command is the following:

1. If a beam spanning between two supports is subdivided into many sub-beams this parameter will combine them into one member. It can also be used to combine members to form one continuous beam spanning over more than two supports.

2. When two or more members are combined during design plastic or elastic moments will be calculated at the column supports. At all the intermediate nodes (if any) this calculation will be ignored. Please note that the program only recognizes column at right angle to the beam. Inclined column support is ignored.

3. It will calculate sectional forces at 13 sections along the length of the combined member.

4. It will calculate critical loads (similar to that of Design Load Summary) for all active load cases during design. Beams will be combined only when DESIGN BEAM command is issued. The following lines should be satisfied during combination of members:

1. Members to be combined should have same sectional properties if any single span between two column supports of a continuous beam is subdivided into several members.

2. Members to be combined should have same constants (E, Poi ratio, alpha, density and beta angle)

3. Members to be combined should lie in one straight line. 4. Members to be combined should be continuous. 5. Vertical members (i.e. columns) cannot be combined. 6. Same member cannot be used more than once to form two different

combined members. 7. The maximum number of members that can be combined into one

member is 299.

Section 9A1

9-41

Note: Sectional forces and critical load for combined member output will only be available when all the members combined are successfully designed in both flexure and shear. ENSH and RENSH parameters will have to be provided (as and when necessary) even if physical member has been formed. The following lines show a standard example for design to be

performed in IS 13920.

STAAD SPACE

UNIT METER MTON

JOINT COORDINATES

…………………………………..

MEMBER INCIDENCES

…………………………………..

MEMBER PROPERTY INDIAN

…………………………………..

CONSTANTS

…………………….

SUPPORTS

…………………….

DEFINE 1893 LOAD

ZONE 0.05 I 1 K 1 B 1

SELFWEIGHT

JOINT WEIGHT

……………………….

LOAD 1 SEISMIC LOAD IN X DIR

1893 LOAD X 1

LOAD 2 SEISMIC LOAD IN Z DIR

1893 LOAD Z 1

LOAD 3 DL

MEMBER LOAD

…… UNI GY -5

LOAD 4 LL


Section 9A1

9-42

MEMBER LOAD

……. UNI GY -3

LOAD COMB 5 1.5(DL+LL)

3 1.5 4 1.5

LOAD COMB 6 1.2(DL+LL+SLX)

1 1.2 3 1.2 4 1.2

LOAD COMB 7 1.2(DL+LL-SLX)

1 1.2 3 1.2 4 -1.2

LOAD COMB 8 1.2(DL+LL+SLZ)

2 1.2 3 1.2 4 1.2

LOAD COMB 9 1.2(DL+LL-SLZ)

2 1.2 3 1.2 4 -1.2

PDELTA ANALYSIS

LOAD LIST 5 TO 9

START CONCRETE DESIGN

CODE IS13920

UNIT MMS NEWTON

FYMAIN 415 ALL

FC 20 ALL

MINMAIN 12 ALL

MAXMAIN 25 ALL

TRACK 2.0 ALL

*** Unfactored gravity load on members 110 to 112 is 8 t/m (DL+LL) i.e. 78.46 New/mm

EUDL 78.46 MEMB 110 TO 112

** Members to be combined into one physical member

COMBINE 3.0 MEMB 110 TO 112

*** Plastic moment considered

PLASTIC 1.0 MEMB 110 TO 112

DESIGN BEAM 110 TO 112

DESIGN COLUMN ………

END CONCRETE DESIGN

FINISH

Section 9A1

9-43

9A1.6 Bar Combination

Initially the program selects only one bar to calculate the number

of bars required and area of steel provided at each section along

the length of the beam. Now two bar diameters can be specified to

calculate a combination of each bar to be provided at each section.

The syntax for bar combination is given below.

START BAR COMBINATION MD1 <bar diameter> MEMB <member list> MD2 <bar diameter> MEMB <member list> END BAR COMBINATION

MD2 bar diameter should be greater than MD1 bar diameter. The

typical output for bar combination is shown below:

OUTPUT FOR BAR COMBINATION

----------------------------------------------------------------------------

| M A I N R E I N F O R C E M E N T |

----------------------------------------------------------------------------

SECTION | 0.0- 2166.7 | 2166.7- 6500.0 | 6500.0- 8666.7 |

| mm | mm | mm |

----------------------------------------------------------------------------

TOP | 6-20í + 1-25í | 2-20í + 1-25í | 2-20í |

| in 2 layer(s) | in 1 layer(s) | in 1 layer(s) |

Ast Reqd| 2330.22 | 1029.90 | 582.55 |

Prov| 2376.79 | 1119.64 | 628.57 |

Ld (mm) | 940.2 | 940.2 | 940.2 |

----------------------------------------------------------------------------

BOTTOM | 4-20í | 2-20í | 2-20í |

| in 1 layer(s) | in 1 layer(s) | in 1 layer(s) |

Ast Reqd| 1165.11 | 582.55 | 582.55 |

Prov| 1257.14 | 628.57 | 628.57 |

Ld (mm) | 940.2 | 940.2 | 940.2 |

----------------------------------------------------------------------------

The beam length is divided into three parts, two at its ends and one

at span. Ld gives the development length to be provided at the two

ends of each section.


Section 9A1

9-44

Sample example showing calculation of design shear force as per

Clause 6.3.3

For Beam No. 1 and 2

Section Width b 250 mm

Depth D 500 mm

Characteristic Strength of Steel fy 415 N/sq. mm Characteristic Strength of Concrete fck 20 N/sq. mm Clear Cover 25 mm Bar Diameter 12 mm Effective Depth d 469 mm Eudl w 6.5 N/sq. mm Length L 4000 mm Ast_Top_A 339.29 sq. mm Ast_Bot_A 226.19 sq. mm Ast_Top_B 226.19 sq. mm Ast_Bot_B 339.29 sq. mm

Section 9A1

9-45

Steps

Calculation of Simple Shear

Simple shear from gravity load on span =

Va = Vb = 1.2 * w * L / 2 = 15600N

Calculation of Moment Of Resistances Based On Area Of Steel Provided

Sagging Moment Of Resistance of End A Mu, as =

0.87 * fy * Ast_Bot_A * d * ( 1 - Ast_Bot_A * fy / b * d * fck)

= 36768130.05 N

Hogging Moment Of Resistance of End A Micah =

0.87 * fy * Ast_Top_A * d * ( 1 - Ast_Top_A * fy / b * d * fck)

= 54003057.45 N

Sagging Moment Of Resistance of End A Mu, bs =

0.87 * fy * Ast_Bot_B * d * ( 1 - Ast_Bot_B * fy / b * d * fck)

= 54003057.45 N

Hogging Moment Of Resistance of End A Mob =

0.87 * fy * Ast_Top_B * d * ( 1 - Ast_Top_B* fy / b * d * fck)

= 36768130.05 N

Calculation of Shear Force Due To Formation Of Plastic Hinge At Both Ends Of The Beam Plus The Factored Gravity Load On Span

FIG1: SWAY TO RIGHT

Vur,a = Va - 1.4 [ ( Mu,as + Mu,bh ) / L ] = -10137.69104 N Vur,b = Va + 1.4 [ ( Mu,as + Mu,bh ) / L ] = 41337.69104 N


Section 9A1

9-46

FIG2: SWAY TO LEFT

Vul,a = Va + 1.4 [ ( Mu,ah + Mu,bs ) / L ] = 53402.14022 N

Vul,b = Va - 1.4 [ ( Mu,ah + Mu,bs ) / L ] = - 22202.14022 N Design Shear Force Shear Force From Analysis At End A , Va,anl = 11.56 N Design Shear Force At End A, Vu,a = Max ( Va,anl, Vur,a, Vul,a) = 53402.14022 N

Shear Force From Analysis At End B , Vb,anl = -6.44 N Design Shear Force At End B, Vu,b = Max ( Vb,anl, Vur,b, Vul,b) = 41337.69104 N

For Beam No. 3

Section Width b 300 mm

Depth D 450 mm

Characteristic Strength of Steel fy 415 N/sq. mm

Characteristic Strength of Concrete fck 20 N/sq. mm

Clear Cover 25 mm

Bar Diameter 12 mm

Effective Depth d 419 mm

Eudl w 6.5 N/sq. mm

Length L 3000 mm

Ast_Top_A 226.19 sq. mm

Ast_Bot_A 339.29 sq. mm

Ast_Top_B 452.39 sq. mm

Ast_Bot_B 226.19 sq. mm

Section 9A1

9-47

Calculation of Simple Shear

Simple shear from gravity load on span =

Va = Vb = 1.2 * w * L / 2 = 11700N

Calculation of Moment Of Resistances Based On Area Of Steel Provided

Sagging Moment Of Resistance of End A Mu,as =

0.87 * fy * Ast_Bot_A * d * ( 1 - Ast_Bot_A * fy / b * d * fck)

= 48452983 N

Hogging Moment Of Resistance of End A Mu,ah =

0.87 * fy * Ast_Top_A * d * ( 1 - Ast_Top_A * fy / b * d * fck)

= 32940364.5 N

Sagging Moment Of Resistance of End A Mu,bs =

0.87 * fy * Ast_Bot_B * d * ( 1 - Ast_Bot_B * fy / b * d * fck)

= 32940364.5 N

Hogging Moment Of Resistance of End A Mu,bh =

0.87 * fy * Ast_Top_B * d * ( 1 - Ast_Top_B* fy / b * d * fck)

= 63326721.3 N

Calculation of Shear Force Due To Formation Of Plastic Hinge At Both

Ends Of The Beam Plus The Factored Gravity Load On Span

FIG1: SWAY TO RIGHT

Vur,a = Va - 1.4 [ ( Mu,as + Mu,bh ) / L ] = -40463.862 N Vur,b = Va + 1.4 [ ( Mu,as + Mu,bh ) / L ] = 63863.862 N


Section 9A1

9-48

Vul,a = Va + 1.4 [ ( Mu,ah + Mu,bs ) / L ] = 42444.3402 N

Vul,b = Va - 1.4 [ ( Mu,ah + Mu,bs ) / L ] = -15144.34 N Design Shear Force Shear Force From Analysis At End A , Va,anl = -10.31 N Design Shear Force At End A, Vu,a = Max ( Va,anl, Vur,a, Vul,a) = 42444.3402 N

Shear Force From Analysis At End B , Vb,anl = -23.81 N Design Shear Force At End B, Vu,b = Max ( Vb,anl, Vur,b, Vul,b) = 63863.862 N

9-49

Steel Design Per IS800

9B.1 Design Operations

STAAD contains a broad set of facilities for designing structural

members as individual components of an analyzed structure. The

member design facilities provide the user with the ability to carry

out a number of different design operations. These facilities may

be used selectively in accordance with the requirements of the

design problem. The operations to perform a design are:

Specify the members and the load cases to be considered in the

design.

Specify whether to perform code checking or member

selection.

Specify design parameter values, if different from the default

values.

Specify whether to perform member selection by optimization.

These operations may be repeated by the user any number of times

depending upon the design requirements. The entire ISI steel

section table is supported. Section 8B.13 describes the

specification of steel sections.

Section 9B


Section 9B

9-50

9B.2 General Comments

This section presents some general statements regarding the

implementation of Indian Standard code of practice (IS:800-1984)

for structural steel design in STAAD. The design philosophy and

procedural logistics for member selection and code checking are

based upon the principles of allowable stress design. Two major

failure modes are recognized: failure by overstressing, and failure

by stability considerations. The flowing sections describe the

salient features of the allowable stresses being calculated an d the

stability criteria being used. Members are proportioned to resist

the design loads without exceeding the allowable stresses and the

most economic section is selected on the basis of least weight

criteria. The code checking part of the program checks stability

and strength requirements and reports the critical loading

condition and the governing code criteria. It is generally assumed

that the user will take care of the detailing requirements like

provision of stiffeners and check the local effects such as flange

buckling and web crippling.

9B.3 Allowable Stresses

The member design and code checking in STAAD are based upon

the allowable stress design method as per IS:800 (1984). It is a

method for proportioning structural members using design loads

and forces, allowable stresses, and design limitations for the

appropriate material under service conditions. It would not be

possible to describe every aspect of IS:800 in this manual. This

section, however, will discuss the salient features of the allowable

stresses specified by IS:800 and implemented in STAAD.

Appropriate sections of IS:800 will be referenced during the

discussion of various types of allowable stresses.

Section 9B

9-51

9B.3.1 Axial Stress

Tensile Stress

The allowable tensile stress, as calculated in STAAD as per IS:800

is described below.

The permissible stress in axial tension, at in MPa on the net

effective area of the sections shall not exceed

at = 0.6 fy

where,

fy = minimum yield stress of steel in Mpa

Compressive Stress

Allowable compressive stress on the gross section of axially

loaded compression members shall not exceed 0.6fy nor the

permissible stress ac calculated based on the following formula:

(Clause: 5.1.1)

f f

nccf

nyf

0 6.

[( ) ( ) ]

where,

ac = Permissible stress in axial compression, in Mpa

fy = Yield stress of steel, in Mpa

fcc = Elastic critical stress in compression = 2 E/2

E = Modulus of elasticity of steel, 2 X 105 Mpa

=l/r = Slenderness ratio of the member, ratio of the effective

length to appropriate radius of gyration

n = A factor assumed as 1.4.


Section 9B

9-52

9B.3.2 Bending Stress

The allowable bending stress in a member subjected to bending is

calculated based on the following formula: (Clause: 6.2.1)

bt or bc = 0.66 fy

where,

bt = Bending stress in tension

bc = Bending stress in compression

fy = Yield stress of steel, in MPa

For an I-beam or channel with equal flanges bent about the axis of

maximum strength (z-z axis), the maximum bending compressive

stress on the extreme fibre calculated on the effective section shall

not exceed the values of maximum permissible bending compressive

stress. The maximum permissible bending compressive stress shall be

obtained by the following formula: (Clause: 6.2.2)

6.2.3) :(Clause

])f y(n

)f cb(n

[

1/n

f yf cb0.66σbc

where,

fy = Yield stress of steel, in Mpa

n = A factor assumed as 1.4.

fcb = Elastic critical stress in bending, calculated by the

following formula:

f k X k Yc

c [ ]

Section 9B

9-53

where,

X YIT

r DMP

yr 1

1

20 1 Y =

26.5x10

( / )

k1 = a coefficient to allow for reduction in thickness or

breadth of flanges between points of effective lateral

restraint and depends on , the ratio of the total area of

both flanges at the point of least bending moment to the

corresponding area at the point of greatest bending

moment between such points of restraint.

k2 = a coefficient to allow for the inequality of flanges, and

depends on , the ratio of the moment of inertia of the

compression flange alone to that of the sum of the moment

of the flanges each calculated about its own axis parallel to

the y-yaxis of the girder, at the point of maximum bending

moment.

1 = effective length of compression flange

ry = radius of gyration of the section about its axis of

minimum strength (y-y axis)

T = mean thickness of the compression flange, is equal to the

area of horizontal portion of flange divided by width.

D = overall depth of beam

c1 ,c2 = respectively the lesser and greater distances from the

section neutral axis to the extreme fibres.

9B.3.3 Shear Stress

Allowable shear stress calculations are based on Section 6.4 of IS:800 .

For shear on the web, the gross section taken into consideration consist

of the product of the total depth and the web thickness. For shear

parallel to the flanges, the gross section is taken as 2/3 times the total

flange area.


Section 9B

9-54

9B.3.4 Combined Stress

Members subjected to both axial and bending stresses are

proportioned accordingly to section 7 of IS:800. All members

subject to bending and axial compression are required to satisfy

the equation of Section 7.1.1.(a) for intermediate points, and

equation of Section 7.1.1.(b) for support points.

For combined axial tension and bending the equation of Section

7.1.2. is required to be satisfied.

Cm coefficients are calculated according to the specifications of

Section 7.1.3. information regarding occurrence of sidesway can

be provided through the use of parameters SSY and SSZ. In the

absence of any user provided information, sidesway will be

assumed.

9B.4 Design Parameters

In STAAD implementation of IS:800, the user is allowed complete

control of the design process through the use of design parameters.

Available design parameters to be used in conjunction with IS:800

are listed in Table 7B.1 of this section along with their default

values and applicable restrictions. Users should note that when the

TRACK parameter is set to 1.0 and use in conjunction with this

code, allowable bending stresses in compression (FCY & FCZ),

tension (FTY & FTZ), and allowable shear stress (FV) will be

printed out in Member Selection and Code Check output in Mpa.

When TRACK is set to 2.0, detailed design output will be

provided.

9B.5 Stability Requirements

Slenderness ratios are calculated for all members and checked

against the appropriate maximum values. Section 3.7 of IS:800

Section 9B

9-55

summarizes the maximum slenderness ratios for different types of

members. In STAAD implementation of IS:800, appropriate

maximum slenderness ratio can be provided for each member. If

no maximum slenderness ratio is provided, compression members

will be checked against a maximum value of 180 and tension

members will be checked against a maximum value of 400.

9B.6 Truss Members

As mentioned earlier, a truss member is capable of carrying only

axial forces. So in design no time is wasted in calculating bending

or shear stresses, thus reducing design time considerably.

Therefore, if there is any truss member in an analysis (like bracing

or strut, etc.), it is wise to declare it as a truss member rather than

as a regular frame member with both ends pinned.

9B.7 Deflection Check

This facility allows the user to consider deflection as a criteria in

the CODE CHECK and MEMBER SELECTION processes. The

deflection check may be controlled using three parameters which

are described in Table 7B.1. Note that deflection is used in

addition to other strength and stabil ity related criteria. The local

deflection calculation is based on the latest analysis results.

9B.8 Code Checking

The purpose of code checking is to verify whether the specified

section is capable of satisfying applicable design code

requirements. The code checking is based on the IS:800 (1984)

requirements. Forces and moments at specified sections of the

members are utilized for the code checking calculations. Sections

may be specified using the BEAM parameter or the SECTION

command. If no sections are specified, the code checking is based

on forces and moments at the member ends.


Section 9B

9-56

The code checking output labels the members as PASSed or

FAILed. In addition, the critical condition (applicable IS:800

clause no.), governing load case, location (distance from the start)

and magnitudes of the governing forces and moments are also

printed out.

9B.9 Member Selection

STAAD is capable of performing design operations on specified

members. Once an analysis has been performed, the program can

select the most economical section, that is, the lightest section,

which satisfies the applicable code requirements. The section

selected will be of the same type (I-Section, Channel etc.) as

originally specified by the user. Member selection may be

performed with all types of steel sections listed in Section 7B.13

and user provided tables. Selection of members, whose properties

are originally provided from user specified table, will be limited to

sections in the user provided table. Member selection can not be

performed on members whose cross sectional properties are

specified as PRISMATIC.

The process of MEMBER SELECTION may be controlled using

the parameters listed in Table 8B.1. It may be noted that the

parameters DMAX and DMIN may be used to specify member

depth constraints for selection. If PROFILE parameter is provided,

the search for the lightest section is restricted to that profile. Up to

three (3) profiles may be provided for any member with a section

being selected from each one.

9B.10 Member Selection By Optimization

Steel section selection of the entire structure may be optimized.

The optimization method utilizes a state-of-the -art numerical

technique which requires automatic multiple analysis. The user

may start without a specifically designated section. However, the

section profile type (BEAM, COLUMN, CHANNEL, ANGLE etc.)

must be specified using the ASSIGN command (see Chapter 6).

Section 9B

9-57

The optimization is based on member stiffness contributions and

corresponding force distributions. An optimum member size is

determined through successive analysis/design iterations. This

method requires substantial computer time and hence should be

used with caution.

9B.11 Tabulated Results of Steel Design

For code checking or member selection, the program produces the

result in a tabulated fashion. The items in the output table are

explained as follows:

a) MEMBER refers to the member number for which the design

is performed

b) TABLE refers to the INDIAN steel section name which has

been checked against the steel code or has been selected.

c) RESULT prints whether the member has PASSED or FAILed.

If the RESULT is FAIL, there will be an asterisk (*) mark in

front of the member number.

d) CRITICAL COND refers to the section of the IS:800 code

which governs the design.

e) RATIO prints the ratio of the actual stresses to allowable

stresses for the critical condition. Normally a value of 1.0 or

less will mean the member has passed.

f) LOADING provides the load case number which governs the

design.

g) FX, MY and MZ provide the axial force, moment in local y-

axis and moment in local z-axis respectively. Although

STAAD does consider all the member forces and moments

(except torsion) to perform design, only FX,MY and MZ are

printed since they are the ones which are of interest , in most

cases.


Section 9B

9-58

h) LOCATION specifies the actual distance from the start of the

member to the section where design forces govern.

i) If the parameter TRACK is set to 1.0, the program will block

out part of the table and will print allowable bending stresses

in compression (FCY & FCZ) and tension (FTY & FTZ),

allowable axial stress in compression (FA), and allowable

shear stress (FV). When the parameter TRACK is set to 2.0

for all members parameter code values are as shown in Fig

8B.1.

STAAD.Pro CODE CHECKING - (ISA ) ***********************

|---------------------------------------------------------------------------|

| Y PROPERTIES |

|************* | IN CM UNIT |

| * |=============================| ===|=== ------------ |

|MEMBER 7 * | | | AX = 72.4 |

| * | ST ISLB400 | | --Z AY = 32.0 |

|DESIGN CODE * | | | AZ = 27.5 |

| IS-800 * =============================== ===|=== SY = 86.8 |

| * SZ = 965.3 |

| * |<---LENGTH (ME= 3.00 --->| RY = 3.1 |

|************* RZ = 16.3 |

| |

| 104.6( KN-METR) |

|PARAMETER |L1 STRESSES |

|IN NEWT MM | IN NEWT MM|

|--------------- + -------------|

| KL/R-Y= 95.4 | FA = 84.8 |

| KL/R-Z= 18.4 + fa = 1.6 |

| UNL = 3000.0 | FCZ = 116.6 |

| C = 400.0 + FTZ = 165.0 |

| CMY = 0.85 | FCY = 165.0 |

| CMZ = 0.85 + FTY = 165.0 |

| FYLD = 249.9 | L3 fbz = 108.4 |

| NSF = 0.9 +---+---+---+---+---+---+---+---+---+---| fby = 0.0 |

| DFF = 325.0 92.7 FV = 100.0 |

| dff = 4383.0 ABSOLUTE MZ ENVELOPE |

| (WITH LOAD NO.) |

| |

| MAX FORCE/ MOMENT SUMMARY ( KN-METR) |

| ------------------------- |

| |

| AXIAL SHEAR-Y SHEAR-Z MOMENT-Y MOMENT-Z |

| |

| VALUE -23.7 61.3 0.0 0.0 104.6 |

| LOCATION 0.0 0.0 0.0 0.0 0.0 |

| LOADING 3 1 0 0 1 |

| |

|***************************************************************************|

|* *|

|* DESIGN SUMMARY ( KN-METR) *|

|* -------------- *|

|* *|

|* RESULT/ CRITICAL COND/ RATIO/ LOADING/ *|

| FX MY MZ LOCATION |

| ====================================================== |

| PASS IS-7.1.2 0.667 1 |

| 9.62 T 0.0 -104.6 0.00 |

| |

| DEFLECTION * PASS |

| RATIO: 0.074 LOADING: 3 LOCATION: 0.67 |

|* *|

|***************************************************************************|

Section 9B

9-59

9B.12 Indian Steel Table

This is an important feature of the program since the program will

read section properties of a steel member directly from the latest

ISI steel tables (as published in ISI-800). These properties are

stored in memory corresponding to the section designation (e.g.

ISMB250, etc.). If called for, the properties are also used for

member design. Since the shear areas are built in to these tables,

shear deformation is always considered for these members.

Almost all ISI steel tables are available for input. A complete

listing of the sections available in the built -in steel section library

may be obtained using the tools of the graphical user interface.

Following are the descriptions of all the types of sections

available:

Rolled Steel Beams (ISJB, ISLB, ISMB and ISHB).

All rolled steel beam sections are available the way they are

designated in the ISI handbook., e.g. ISJB225, ISWB400, etc.

20 TO 30 TA ST ISLB325

NOTE:

In case of two identical beams, the heavier beam is designated

with an „A” on the end., e.g. ISHB400 A, etc.

1 TO 5 TA ST ISHB400A


Section 9B

9-60

Rolled Steel Channels (ISJC, ISLC and ISMC)

All these shapes are available as listed in ISI section handbook.

Designation of the channels are per the scheme used by ISI.

10 TO 20 BY 2 TA ST ISMC125

12 TA ST ISLC300

Double Channels

Back to back double channels, with or without spacing between

them, are available. The letter D in front of the section name will

specify a double channel, e.g. D ISJC125, D ISMC75 etc.

21 22 24 TA D ISLC225

Rolled Steel Angles

Both rolled steel equal angles and unequal angles are available for

use in the STAAD implementation of ISI steel tables. The

following example with explanations will be helpful in

understanding the input procedure:

ISA 150 X 75 X 8 Angle symbol Thickness in mm Long leg length in mm Short leg length in mm

At present there is no standard way to define the local y and z axes

for an angle section. The standard section has local axis system as

illustrated in Fig.2.4 of this manual. The standard angle is

specified as:

51 52 53 TA ST ISA60X60X6

Section 9B

9-61

This specification has the local z-axis ( i.e., the minor axis

corresponding to the V-V axis specified in the steel tables. Many

engineers are familiar with a convention used by some other

programs in which the local y-axis is the minor axis. STAAD

provides for this convention by accepting the command:

54 55 56 TA RA ISA50X30X6 (RA denotes reverse angle)

Double Angles

Short leg back to back or long leg back to back double angles can

be specified by inputting the word SD or LD, respectively, in front

of the angle size. In case of an equal angle either LD or SD will

serve the purpose. For example,

14 TO 20 TA LD ISA50X30X5 SP 1.5

23 27 TA SD ISA75X50X6

Rolled Tees (ISHT, ISST, ISLT and ISJT)

All the rolled tee sections are available for input as they are

specified in the ISI handbook. Following example illustrates the

designated method.

1 2 5 8 TA ST ISNT100

67 68 TA ST ISST250

Pipes (Circular Hollow Sections)

To designate circular hollow sections from ISI tables, use PIP

followed by the numerical value of diameter and thickness of the

section in mm omitting the decimal section of the value provided

for diameter. Following example will illustrate the designation.


Section 9B

9-62

10 15 TA ST PIP 213.2

(Specifies a 213 mm dia. pipe with 3.2 mm wall thickness)

Circular pipe sections can also be specified by providing the

outside and inside diameters of the section. For example,

1 TO 9 TA ST PIPE OD 25.0ID 20.0

(specifies a pipe with outside dia. of 25 and inside dia. of 20

in current length units)

Only code checking and no member selection will be performed if

this type of specification is used.

Tubes (Rectangular or Square Hollow Sections)

Designation of tubes from the ISI steel table is illustrated below. TUB 400 200 12.5 Tube Symbol Thickness in mm Height in mm Width in mm Example:

15 TO 25 TA ST TUB 160808

Tubes, like pipes, can also be input by their dimensions (Height,

Width and Thickness) and not by any table designations.

6 TA ST TUBE DT 8.0 WT 6.0 TH 0.5 is a tube that has a height

of 8, a width of 6, and a wall thickness of 0.5.

Section 9B

9-63

Note that only code checking and no member selection is

performed for TUBE sections specified this way.

Plate And Angle Girders (With Flange Plates)

All plate and angle grinders (with flange plates) are available as

listed in ISI section handbook. The following example with

explanations will be helpful in understanding the input procedure.

I 1000 12 A 400 12

A F

B E

C D

A Plate and angle girder symbol.

B Web plate width in mm.

C Web plate thickness in mm.

D Flange angle (Flange angle key below):

E Flange plate width in mm.

F Flange plate thickness in mm.

SYMBOL ANGLE(A X B X t)(all in mm)

A 150X150X18

B 200X100X15

C 200X150X18

E 200X200X18


Section 9B

9-64

SINGLE JOIST WITH CHANNELS AND PLATES ON THE

FLANGES TO BE USED AS GIRDERS

All single joist with channel and plates on the flanges to be used

as girders are available as listed in ISI section handbook. The

following example with explanations will be helpful in

understanding the input procedure.

IW 450 350 X 10 20

A E

B D

C

A Joist Designation: IW450=ISWB450

B Top flange channel designation:

350=ISMC350

C Constant (always X).

D Top flange plate thickness in mm.

NOTE: D is 0 for no plate.

E Bottom flange plate thickness in mm.

NOTE:

The heavier ISWB600 has been omitted, since the lighter

ISWB600 is more efficient.

Section 9B

9-65


specified number till it is specified again. This is the way STAAD

works for all codes.

Table 9B.1 Indian Steel Design - IS : 800 Parameters

Parameter

Name


KY 1.0 K value in local y-axis. Usually, this is minor axis.

KZ 1.0 K value in local z-axis. Usually, this is major axis.

LY Member Length Length in local y-axis to calculate slenderness ratio.

LZ Member Length Same as above except in local z-axis (major).

FYLD 250 MPA

(36.25 KSI) Yield strength of steel.

NSF 1.0 Net section factor for tension members.

UNL Member Length Unsupported length for calculating allowable bending stress.

UNF 1.0 Same as above provided as a fraction of actual member length.

SSY 0.0 0.0 = Sidesway in local y-axis. 1.0 = No sidesway

SSZ 0.0 Same as above except in local z-axis.

CMY

CMZ

0.85 for sidesway and

calculated for no sidesway

Cm value in local y & z axes

MAIN 180 (Comp. Memb.)

Allowable Kl/r for slenderness calculations for compression members.

TMAIN 400 (Tension Memb)

Allowable Kl/r for slenderness calculations for tension members.

TRACK 0.0

0.0 = Suppress critical member stresses 1.0 = Print all critical member stresses 2.0 = Print expanded output. If there is

deflection check it will also print the governing load case number for deflection check whenever critical condition for design is not DEFLECTION. (see fig.8B.1)


Section 9B

9-66

Table 9B.1 Indian Steel Design - IS : 800 Parameters

Parameter

Name


DMAX 100.0 cm. Maximum allowable depth.

DMIN 0.0 cm. Minimum allowable depth.

RATIO 1.0 Permissible ratio of the actual to allowable stresses.

BEAM 3.0

0.0 = design only for end moments and those at locations specified by the SECTION command.

1.0 = calculate section forces at twelfth points along the beam, design at each intermediate location and report the critical location where ratio is maximum.

PROFILE - Search for the lightest section for the profile mentioned.

DFF None

(Mandatory for deflection check)

"Deflection Length" / Maxm. allowable local deflection

DJ1 Start Joint of member

Joint No. denoting starting point for calculation of "Deflection Length" (See Note 1)

DJ2 End Joint of member

Joint No. denoting end point for calculation of "Deflection Length" (See Note 1)

NOTES:

1) "Deflection Length" is defined as the length that is used for

calculation of local deflections within a member. It may be

noted that for most cases the "Deflection Length" will be equal

to the length of the member. However, in some situations, the

"Deflection Length" may be different. For example, refer to

the figure below where a beam has been modeled using four

joints and three members. Note that the "Deflection Length"

for all three members will be equal to the total length of the

beam in this case. The parameters DJ1 and DJ2 should be used

to model this situation. Also the straight line joining DJ1 and

DJ2 is used as the reference line from which local deflections

are measured. Thus, for all three members here, DJ1 should be

"1" and DJ2 should be "4".

Section 9B

9-67

D = Maximum local deflection for members1 2 and 3.

D

1

2 3

4

1

2 3

EXAMPLE : PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

2) If DJ1 and DJ2 are not used, "Deflection Length" will default

to the member length and local deflections will be measured

from original member line.

3) The above parameters may be used in conjunction with other

available parameters for steel design.

9B.13 Column With Lacings And Battens

For columns with large loads it is desirable to build rolled sections

at a distance and inter-connect them. The joining of element

sections is done by two ways:

a) Lacing and b) Batten

Double channel sections (back-to-back and face-to-face) can be

joined either by lacing or by batten plates having rivetted or

welded connection.

Table 8B.2 gives the parameters that are required for Lacing or

batten design. These parameters will have to be provided in unit

NEW MMS along with parameters defined in Table 9B.1.


Section 9B

9-68




Table 9B.2 Indian Concrete Design IS800 Parameters

Parameter

Name


CTYPE 1 Type of joining

CTYPE = 1 implies single lacing with rivetted connection

CTYPE = 2 implies double lacing with rivetted connection

CTYPE = 3 implies single lacing with welded connection

CTYPE = 4 implies double lacing with welded connection

CTYPE = 5 implies batten with rivetted connection

CTYPE = 6 implies batten with welded connection

THETA 50 degree Angle of inclination of lacing bars. It should lie between 40 degree and 70 degree.

DBL 20 mm Nominal diameter of rivet

FVB 100 N/mm2 Allowable shear stress in rivet

FYB 300 N/mm2 Allowable bearing stress in rivet

WMIN 6 mm Minimum thickness of weld

WSTR 108 N/mm2 Allowable welding stress

EDIST 32 mm (Rivetted Connection)

25 mm (Welded Connection)

Edge Distance

Section 9B

9-69

Table 9B.2 Indian Concrete Design IS800 Parameters

Parameter

Name


DCFR 0.0 0.0 implies double channel back-to-back.

1.0 Implies double channel face-to-face.

This parameter is used when member properties are defined through user provided table using GENERAL option.

COG 0.0 mm Centre of gravity of the channel. This parameter is used when member properties are defined through user provided table using GENERAL option.

SPA 0.0 mm Spacing between double channels. This parameter is used when member properties are defined through user provided table using GENERAL option.


Section 9B

9-70

9-71


9C.1 General Comments

This section presents some general statements regarding the

implementation of Indian Standard code of practice (IS:802-1995 –

Part 1) for structural steel design for overhead transmission line

towers in STAAD. The design philosophy and procedural logistics

for member selection and code checking are based upon the

principles of allowable stress design. Two major failure modes are

recognized: failure by overstressing, and failure by stability

considerations. The flowing sections describe the salient features

of the allowable stresses being calculated and the stability criteria

being used. Members are proportioned to resist the design loads

without exceeding the allowable stresses and the most economic

section is selected on the basis of least weight criteria. The code

checking part of the program checks stability and strength

requirements and reports the critical loading condition and the

governing code criteria.

9C.2 Allowable Stresses

The member design and code checking in STAAD are based upon

the allowable stress design method as per IS:802 (1995). It is a

method for proportioning structural members using design loads

and forces, allowable stresses, and design limitations for the

appropriate material under service conditions.

This section discusses the salient features of the allowable stresses

specified by IS:802 and implemented in STAAD.

Section 9C


Section 9C

9-72

9C.2..1 Axial Stress

Tensile Stress

The allowable tensile stress, as calculated in STAAD as per IS:802

is described below.

The estimated tensile stresses on the net effective sectional area in

various members, multiplied by the appropriate factor of safety

shall not exceed minimum guaranteed yield stress of the material.

Thus, the permissible stress in axial tension, at in MPa on the net

effective area of the sections shall not exceed

at = fy

where,

fy = minimum yield stress of steel in Mpa

Compressive Stress

The estimated compressive stresses in various members multiplied

by the appropriate factor of safety shall not exceed the value given

by the formulae described below.

Condition 1: If

yFt

b

t

b 210

lim

CCr/KL

Stress Fa= yFCc

r/KL

2

11

2

N/mm2

CCr/KL

Section 9C

9-73

Stress Fa = 2

2

/ rKL

E N/mm2

Condition 2: If

lim

t

b

t

b

yF

378 when Fy is the N/mm2

formulae given in condition 1 shall be used substituting for Fy the

value Fcr given by:

Fcr = y

lim

F

t

b

t

b677.0

677.1

Condition 3:

t

b>

yF

378when Fy is the N/mm2 formulae given in

condition 1 shall be used substituting for Fy the value Fcr given by

Fcr = 2

t

b

65550

In which CC =

yF

E2

where,

Fa = allowable unit stress in compression, Mpa

Fy = minimum guaranteed yield stress of the material, Mpa

K = restraint factor,

L = unbraced length of the compression member in cm, and

R = appropriate radius of gyration in cm.

E = modulus of elasticity of steel in N/mm2


Section 9C

9-74

r

KL = largest effective slenderness ratio of any unbraced segment

of the member,

b = distance from edge of the fillet to the extreme fibre in mm, and

t = thickness of flange in mm.

Note : The maximum permissible value of b/t for any type of steel

shall not exceed 25.

9C.3 Stability Requirements

Slenderness ratios are calculated for all members and checked

against the appropriate maximum values. Following are the default

values used in STAAD:

Compression Members:

Members Slenderness

value

Leg Members, ground wire peak member and lower

members of cross arms in compression 120

Other members carrying computed stress 200

Redundant members and those carrying nominal

stresses 250

Section 9C

9-75

Slenderness ratios of compression members are determined as

follows:

If ELA number given in the input for any particular member is

such that condition for L/r ratio to fall within the specified range

is not satisfied, STAAD goes on by the usual way of finding

slenderness ratio using K*L/r formula.

ELA NO.

Type of members

Value of KL/r

1 Leg sections or joint members bolted

at connections in both faces

L/r

2 Members with concentric loading at

both ends of the unsupported panel

with values of L/r up to and

including 120

L/r

3 Member with concentric loading at

one end and normal eccentricities at

the other end of the unsupported

panel for value of L/r up to and

including 120

30 + 0.75L/r

4 Members with normal framing

eccentricities at both ends of the

unsupported panel for values of L/r

up to and including 120

60 + 0.5L/r

5 Member unrestrained against

rotation at both ends of the

unsupported panel for value of L/r

from 120 to 200

L/r

6 Members partially restrained against

rotation at one end of the


over 120 and up to and including 225

28.6 + 0.762L/r

7 Members partially restrained against

rotation at both ends of the


over 120 and up to and including 250

46.2 + 0.615L/r


Section 9C

9-76

Tension Members:

Slenderness ratio KL/r of a member carrying axial tension only,

shall not exceed 400.

9C.4 Minimum Thickness Requirement

As per Clause7.1 of IS: 802-1995 minimum thickness of different

tower members shall be as follows:

Members Minimum Thickness, mm

Galvanized Painted

Leg Members, ground wire peak

member and lower members of

cross arms in compression

5 6

Other members

4 5

9C.5 Code Checking

The purpose of code checking is to verify whether the specified

section is capable of satisfying applicable design code

requirements. The code checking is based on the IS:802 (1995)

requirements. Axial forces at two ends of the members are utilized

for the code checking calculations.

The code checking output labels the members as PASSed or

FAILed. In addition, the critical condition, governing load case,

location (distance from the start) and magnitudes of the governing

forces are also printed out. Using TRACK 9 option calculation

steps are also printed.

Section 9C

9-77

9C.5.1 Design Steps

The following are the steps followed in member design.

Step 1

Thickness of the member (maximum of web and flange

thicknesses) is checked against minimum allowable thickness,

depending upon whether the member is painted or galvanised.

Step 2

If the minimum thickness criterion is fulfilled, the program

determines whether the member is under compression or tension

for the loadcase under consideration. Depending upon whether the

member is under tension or compression the slenderness ratio of

the member is calculated. This calculated ratio is checked against

allowable slenderness ratio.

Step 3

If the slenderness criterion is fulfilled check against allowable

stress is performed. Allowable axial and tensile stresses are

calculated. If the member is under tension and there is no user

defined net section factor (NSF), the net section factor is

calculated by the program itself (Refer Section 8C.10). Actual

axial stress in the member is calculated. The ratio for actual stress

to allowable stress, if less than 1.0 or user defined value, the

member has passed the check.

Step 4

Number of bolts required for the critical loadcase is calculated.


Section 9C

9-78

9C.6 Member Selection



select the most economical section, that is, the lightest section,

which satisfies the applicable code requirements. The section

selected will be of the same type (either angle or channel) as

originally specified by the user. Member selection may be

performed with all angle or channel sections and user provided

tables. Selection of members, whose properties are originally

provided from user specified table, will be limited to sections in

the user provided table.

The process of MEMBER SELECTION may be controlled using

the parameters listed in Table 8B.1. It may be noted that the

parameters DMAX and DMIN may be used to specify member

depth constraints for selection. If PROFILE parameter is provided,

the search for the lightest section is restricted to that profile. Up to

three (3) profiles may be provided for any member with a section

being selected from each one.

9C.7 Member Selection by Optimization

Steel section selection of the entire structure may be optimized .

The optimization method utilizes a state-of-the -art numerical

technique which requires automatic multiple analysis. The

optimization is based on member stiffness contributions and

corresponding force distributions.

An optimum member size is determined through successive

analysis/design iterations. This method requires substantial

computer time and hence should be used with caution.

Section 9C

9-79

9C.8 Tabulated Results of Steel Design

DETAILS OF CALCULATION

----------------------

CHECK FOR MINIMUM THICKNESS

---------------------------

TYPE : GALVANISED

MIN. ALLOWABLE THICKNESS : 5.0 MM

ACTUAL THICKNESS : 10.0 MM

RESULT : PASS


Section 9C

9-80

CHECK FOR SLENDERNESS RATIO

---------------------------

VALUE OF L/r : 90.16

EQN. USED TO FIND KL/r : 60.0 + 0.5*L/r

ACTUAL VALUE OF KL/r : 105.08

ALLOWABLE KL/r : 120.00

RESULT : PASS

CALCULATION OF ALLOWABLE STRESS

--------------------------------

CRITICAL CONDITION : COMPRESSION

Cc : sqrt(2*3.141592*3.141592*E/fy) : 127.22

b : LENGTH OF LEG - WEB THICKNESS - ROOT RADIUS

: 150.0 - 10.0 - 11.0 : 129.0 MM

(b/t)lim : 210/sqrt(fy) : 13.28

(b/t)cal : 12.90

(b/t)cal <= (b/t)lim AND KL/r <= Cc

ALLOWABLE AXIAL COMP. STRESS : (1 -0.5*(KL/r/Cc)*(KL/r/Cc))*fy :

164.72 MPA

CHECK AGAINST PERMISSIBLE STRESS

--------------------------------

DESIGN AXIAL FORCE : 250000.00 N

ACTUAL AXIAL COMP. STRESS : 250000.00 / 2552.0 : 97.96 MPA

RESULT : PASS

BOLTING

-------

BOLT DIA : 16 MM

SHEARING CAP : 20.11 KN

BEARING CAP : 38.40 KN

BOLT CAP : 20.11 KN

NO. OF BOLTS REQD. : 13

Section 9C

9-81

9C.9 Parameter Table for IS 802




Table 9C.1 Indian Steel Design - IS 802 Parameters

Parameter

Name




LY Member Length Unbraced length in local z-axis to calculate slenderness ratio.

LZ Member Length Unbraced length in local z-axis to calculate slenderness ratio.

FYLD 250 MPA Yield Strength of steel

MAIN 1.0 Type of member to find allowable Kl/r for slenderness calculations for members.

1.0 = Leg, Ground wire peak and lower members of cross arms in compression (KL/r = 120)

2.0 = Members carrying computed stress (KL/r = 200)

3.0 = Redundant members and members carrying nominal stresses (KL/r = 250)

4.0 = Tension members (KL/r = 400)

10.0 = Do not perform KL/r check

Any value greater than 10.0 indicates user defined allowable KL/r ratio. For this case KY and KZ values are must to find actual KL/r ratio of the member.

DMAX 100.0 cm. Maximum allowable depth.

DMIN 0.0 cm. Minimum allowable depth.


Section 9C

9-82


Parameter

Name


TRACK 0.0 0.0 = Suppress critical member stresses

1.0 = Print all critical member stresses

2.0 = Print expanded output.

9.0 = Print design calculations along with expanded output.

LEG 1.0 This parameter is meant for plain angles.

0.0 = indicates the angle is connected by shorter leg

1.0 = indicates the angle is connected by longer leg

ELA 1.0 This parameter indicates what type of end conditions is to be used. Refer Section 8C.3.

NSF 1.0 Net section factor for tension members

CNSF 0.0 This parameter indicates whether user has defined NSF or the program will calculate it.

0.0 = User has defined NSF

1.0 = Program has to calculate it

DANGLE 0.0 This parameter indicates how the pair of angles are connected to each other. This is required to find whether the angle is in single or double shear and the net section factor.

0.0 = Double angle placed back to back and connected to each side of a gusset plate

1.0 = Pair of angle placed back-to-back connected by only one leg of each angle to the same side of a gusset plate�

DBL 12 mm Diameter of bolt for calculation of number of bolts and net section factor.

FVB 218 MPA Allowable shear stress in bolt

FYB 436 MPA Allowable bearing stress in bolt

Section 9C

9-83


Parameter

Name


GUSSET 5 mm Thickness of gusset plate.

Minimum of the thicknesses of the gusset plate and the leg is used for calculation of the capacity of bolt in bearing

NHL 0.0 mm Deduction for holes.

Default value is one bolt width plus 1.5 mm. If the area of holes cut by any straight, diagonal or zigzag line across the member is different from the default value, this parameter is to be defined.

9C.10 Calculation of Net Section Factor

The procedure for calculating net section factor for angle section is

described below.

Single angle connected by only one leg

Anet = A1 + A2 x K1

Where, A1 = net cross-sectional area of the connected leg

A2 = gross cross-sectional area of the unconnected leg

And K1 = A2 A13

A13

x

x

The area of a leg of an angle = Thickness of angle x (length of leg

– 0.5x thickness of leg)


Section 9C

9-84

Pair of angles placed back-to-back connected by only one leg of

each angle to the same side of a gusset plate

Anet = A1 + A2 x K1

Where A1 = net cross-sectional area of the connected leg

A2 = gross cross-sectional area of the unconnected leg

And K1 = A2 A15

A15

x

x

The area of a leg of an angle = Thickness of angle x (length of leg

– 0.5x thickness of leg)

Double angles placed back to back and connected to each side

of a gusset plate

Anet = gross area – deduction for holes

Net Section Factor

For angle section it is the ratio of the net effective area, Anet to the

gross area.

For channel section net section factor is taken to be 1.0.

Section 9C

9-85

9C.11 Example Problem No. 28

A transmission line tower is subjected to different loading

conditions. Design some members as per IS-802 and show detailed

calculation steps for the critical loading condition.

Given: End Condition = Members with normal framing

eccentricities at both ends of the unsupported panel for

values of L/r up to and including 120

Diameter of the bolt = 16 mm

Thickness of the gusset plate = 8 mm

Net Section Factor is to be calculated.


Section 9C

9-86

STAAD TRUSS

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 3 0 3; 2 1.2 27 1.2; 3 2.8 3 2.8; 4 2.6 6 2.6; 5 2.4 9 2.4; 6 2.2 12 2.2;

7 2 15 2; 8 1.8 18 1.8; 9 1.6 21 1.6; 10 1.4 24 1.4; 11 -3 0 3; 12 -1.2 27 1.2;

13 -2.8 3 2.8; 14 -2.6 6 2.6; 15 -2.4 9 2.4; 16 -2.2 12 2.2; 17 -2 15 2;

18 -1.8 18 1.8; 19 -1.6 21 1.6; 20 -1.4 24 1.4; 21 3 0 -3; 22 1.2 27 -1.2;

23 2.8 3 -2.8; 24 2.6 6 -2.6; 25 2.4 9 -2.4; 26 2.2 12 -2.2; 27 2 15 -2;

28 1.8 18 -1.8; 29 1.6 21 -1.6; 30 1.4 24 -1.4; 31 -3 0 -3; 32 -1.2 27 -1.2;

33 -2.8 3 -2.8; 34 -2.6 6 -2.6; 35 -2.4 9 -2.4; 36 -2.2 12 -2.2; 37 -2 15 -2;

38 -1.8 18 -1.8; 39 -1.6 21 -1.6; 40 -1.4 24 -1.4; 41 1.2 30 1.2;

42 -1.2 30 1.2; 43 1.2 30 -1.2; 44 -1.2 30 -1.2; 45 4.2 27 1.2; 46 7.2 27 1.2;

47 4.2 30 1.2; 48 4.2 27 -1.2; 49 7.2 27 -1.2; 50 4.2 30 -1.2; 51 -4.2 27 1.2;

52 -7.2 27 1.2; 53 -4.2 30 1.2; 54 -4.2 27 -1.2; 55 -7.2 27 -1.2;

56 -4.2 30 -1.2; 57 1.2 33 1.2; 58 -1.2 33 1.2; 59 1.2 33 -1.2;

60 -1.2 33 -1.2; 61 0 35 0;

MEMBER INCIDENCES

1 1 3; 2 3 4; 3 4 5; 4 5 6; 5 6 7; 6 7 8; 7 8 9; 8 9 10; 9 10 2; 10 11 13;

11 13 14; 12 14 15; 13 15 16; 14 16 17; 15 17 18; 16 18 19; 17 19 20; 18 20 12;

19 13 3; 20 14 4; 21 15 5; 22 16 6; 23 17 7; 24 18 8; 25 19 9; 26 20 10;

27 12 2; 28 11 3; 29 1 13; 30 13 4; 31 3 14; 32 14 5; 33 15 4; 34 15 6;

35 16 5; 36 16 7; 37 17 6; 38 17 8; 39 18 7; 40 18 9; 41 19 8; 42 19 10;

43 20 9; 44 20 2; 45 12 10; 46 21 23; 47 23 24; 48 24 25; 49 25 26; 50 26 27;

51 27 28; 52 28 29; 53 29 30; 54 30 22; 55 3 23; 56 4 24; 57 5 25; 58 6 26;

59 7 27; 60 8 28; 61 9 29; 62 10 30; 63 2 22; 64 1 23; 65 21 3; 66 3 24;

67 23 4; 68 4 25; 69 5 24; 70 5 26; 71 6 25; 72 6 27; 73 7 26; 74 7 28;

75 8 27; 76 8 29; 77 9 28; 78 9 30; 79 10 29; 80 10 22; 81 2 30; 82 31 33;

83 33 34; 84 34 35; 85 35 36; 86 36 37; 87 37 38; 88 38 39; 89 39 40; 90 40 32;

91 23 33; 92 24 34; 93 25 35; 94 26 36; 95 27 37; 96 28 38; 97 29 39; 98 30 40;

99 22 32; 100 21 33; 101 31 23; 102 23 34; 103 33 24; 104 24 35; 105 25 34;

106 25 36; 107 26 35; 108 26 37; 109 27 36; 110 27 38; 111 28 37; 112 28 39;

113 29 38; 114 29 40; 115 30 39; 116 30 32; 117 22 40; 118 33 13; 119 34 14;

120 35 15; 121 36 16; 122 37 17; 123 38 18; 124 39 19; 125 40 20; 126 32 12;

127 31 13; 128 11 33; 129 33 14; 130 13 34; 131 34 15; 132 35 14; 133 35 16;

134 36 15; 135 36 17; 136 37 16; 137 37 18; 138 38 17; 139 38 19; 140 39 18;

141 39 20; 142 40 19; 143 40 12; 144 32 20; 145 32 44; 146 12 42; 147 2 41;

148 22 43; 149 42 41; 150 41 43; 151 43 44; 152 44 42; 153 12 41; 154 42 2;

155 22 41; 156 43 2; 157 43 32; 158 44 22; 159 12 44; 160 32 42; 161 41 47;

162 47 45; 163 45 2; 164 47 46; 165 46 45; 166 41 45; 167 43 50; 168 50 48;

169 48 22; 170 50 49; 171 49 48; 172 43 48; 173 47 50; 174 46 49; 175 45 48;

176 41 50; 177 50 46; 178 43 47; 179 47 49; 180 22 50; 181 2 47; 182 22 45;

183 2 48; 184 47 48; 185 50 45; 186 45 49; 187 48 46; 188 42 53; 189 53 51;

190 51 12; 191 53 52; 192 52 51; 193 42 51; 194 44 56; 195 56 54; 196 54 32;

197 56 55; 198 55 54; 199 44 54; 200 53 56; 201 52 55; 202 51 54; 203 42 56;

204 56 52; 205 44 53; 206 53 55; 207 32 56; 208 12 53; 209 32 51; 210 12 54;

211 53 54; 212 56 51; 213 51 55; 214 54 52; 215 44 60; 216 42 58; 217 41 57;

218 43 59; 219 60 59; 220 59 57; 221 57 58; 222 58 60; 223 44 58; 224 42 60;

225 42 57; 226 41 58; 227 44 59; 228 43 60; 229 43 57; 230 41 59; 231 60 57;

232 59 58; 235 33 3; 236 13 23; 237 34 4; 238 14 24; 239 35 5; 240 15 25;

241 36 6; 242 16 26; 243 37 7; 244 17 27; 245 38 8; 246 18 28; 247 39 9;

248 19 29; 249 40 10; 250 20 30; 251 32 2; 252 22 12; 253 44 41; 254 43 42;

Section 9C

9-87

255 60 61; 256 58 61; 257 57 61; 258 59 61;

MEMBER PROPERTY INDIAN

1 TO 18 46 TO 54 82 TO 90 145 TO 148 215 TO 218 TA LD ISA200X150X18 SP 0.01

19 TO 26 28 TO 45 55 TO 62 64 TO 81 91 TO 98 100 TO 125 127 TO 144 155 156 -

159 160 223 224 229 230 235 TO 250 TA ST ISA150X150X10

27 63 99 126 149 TO 154 157 158 161 TO 214 219 TO 222 225 TO 228 231 232 251 -

252 TO 258 TA ST ISA80X50X6

CONSTANTS

E 2.05e+008 ALL

POISSON 0.3 ALL

DENSITY 76.8195 ALL

ALPHA 6.5e-006 ALL

SUPPORTS

1 11 21 31 FIXED

UNIT METER KG

LOAD 1 VERT

SELFWEIGHT Y -1

JOINT LOAD

61 FX 732

46 49 52 55 FX 153

61 FX 1280 FY -1016 FZ 160

46 49 52 55 FX 9006 FY -7844 FZ 1968

2 12 22 32 FX 4503 FY -3937 FZ 1968

LOAD 2 GWBC

SELFWEIGHT Y -1

JOINT LOAD

61 FX 549

46 49 52 55 FX 1148

61 FX 515 FY -762 FZ 2342

46 49 52 55 FX 6755 FY -5906

2 12 22 32 FX 3378 FY -2953

LOAD 3 LEFT PCBC

SELFWEIGHT Y -1

JOINT LOAD

61 FX 549

46 49 52 55 FX 1148

61 FX 960 FY -762

46 49 FX 6755 FY -5906

52 55 FX 4211 FY -4551 FZ 13293

2 12 22 32 FX 3378 FY -2953

LOAD 4 RIGHT PCBC

SELFWEIGHT Y -1

JOINT LOAD

61 FX 549

46 49 52 55 FX 1148

61 FX 960 FY -762

52 55 FX 6755 FY -5906

46 49 FX 4211 FY -4551 FZ 13293

2 12 22 32 FX 3378 FY -2953

PERFORM ANALYSIS

UNIT NEW MMS

PARAMETER

CODE IS802


Section 9C

9-88

LY 2800 MEMB 28 LZ 2800 MEMB 28

MAIN 1.0 MEMB 1

ELA 4 MEMB 1

CNSF 1.0 MEMB 28

DBL 16 ALL

GUSSET 8 ALL

TRACK 9 ALL

CHECK CODE MEMB 1 28

FINISH

Output of design result

Section 9C

9-89

DETAILS OF CALCULATION ---------------------- CHECK FOR MINIMUM THICKNESS --------------------------- TYPE : PAINTED MIN. ALLOWABLE THICKNESS : 6.0 MM ACTUAL THICKNESS : 18.0 MM RESULT : PASS CHECK FOR SLENDERNESS RATIO --------------------------- VALUE OF L/r : 48.49 EQN. USED TO FIND KL/r : 60.0 + 0.5*L/r ACTUAL VALUE OF KL/r : 84.25 ALLOWABLE KL/r : 120.00 RESULT : PASS CALCULATION OF ALLOWABLE STRESS --------------------------------- CRITICAL CONDITION : COMPRESSION Cc : sqrt (2*3.141592*3.141592*E/fy) : 127.24 b : LENGTH OF LEG - WEB THICKNESS - ROOT RADIUS : 200.0 - 18.0 - 13.5 : 168.5 MM (b/t)lim : 210/sqrt(fy) : 13.28 (b/t)cal : 9.36 (b/t)cal <= (b/t)lim AND KL/r <= Cc ALLOWABLE AXIAL COMP. STRESS : (1- 0.5*(KL/r/Cc)*(KL/r/Cc))*fy :

195.15 MPA CHECK AGAINST PERMISSIBLE STRESS -------------------------------- LOAD NO. : 1 DESIGN AXIAL FORCE : 1742002.38 N ACTUAL AXIAL COMP. STRESS :1742002.38 / 11952.0 : 145.75 MPA RESULT : PASS


Section 9C

9-90

BOLTING ------- BOLT DIA : 16 MM SHEARING CAP : 87.66 KN BEARING CAP : 55.81 KN BOLT CAP : 55.81 KN NO. OF BOLTS REQD. : 32

Section 9C

9-91

DETAILS OF CALCULATION ---------------------- CHECK FOR MINIMUM THICKNESS --------------------------- TYPE : PAINTED MIN. ALLOWABLE THICKNESS : 6.0 MM ACTUAL THICKNESS : 10.0 MM RESULT : PASS CHECK FOR SLENDERNESS RATIO --------------------------- VALUE OF L/r : 95.56 EQN. USED TO FIND KL/r : K*L/r ACTUAL VALUE OF KL/r : 95.56 ALLOWABLE KL/r : 400.00 RESULT : PASS CALCULATION OF ALLOWABLE STRESS --------------------------------- CRITICAL CONDITION : TENSION ALLOWABLE AXIAL TENSILE STRESS : 249.94 MPA CHECK AGAINST PERMISSIBLE STRESS -------------------------------- LOAD NO. : 3 DESIGN AXIAL FORCE : 112909.27 N ACTUAL AXIAL TENSILE STRESS : 112909.27 / ( 2903.0*0.801 ) : 48.53 MPA RESULT : PASS BOLTING ------- BOLT DIA : 16 MM SHEARING CAP : 43.83 KN BEARING CAP : 55.81 KN BOLT CAP : 43.83 KN NO. OF BOLTS REQD. : 3 ********** END OF TABULATED RESULT OF DESIGN ***********


Section 9C

9-92

9-93

Design Per Indian Cold Formed

Steel Code

9D.1 General

Provisions of IS:801-1975, including revisions dated May, 1988,

have been implemented. The program allows design of single

(non-composite) members in tension, compression, bending, shear,

as well as their combinations. Cold work of forming strengthening

effects has been included as an option.

9D.2 Cross-Sectional Properties

The user specifies the geometry of the cross-section by selecting

one of the section shape designations from the Gross Section

Property Tables from IS:811-1987 (Specification for cold formed

light gauge structural steel sections).

The Tables are currently available for the following shapes:

Channel with Lips

Channel without Lips

Angle without Lips

Z with Lips

Hat

Shape selection may be done using the member property pages of

the graphical user interface (GUI) or by specifying the section

designation symbol in the input file.

Section 9D

Design Per Indian Cold Formed Steel Code

Section 9D

9-94

The properties listed in the tables are gross section properties.

STAAD.Pro uses unreduced section properties in the structure

analysis stage. Both unreduced and effective section properties are

used in the design stage, as applicable.

9D.3 Design Procedure

The following two design modes are available:

1. Code Checking

The program compares the resistance of members with the applied

load effects, in accordance with IS:801-1975. Code checking is

carried out for locations specified by the user via the SECTION

command or the BEAM parameter. The results are presented in a

form of a PASS/FAIL identifier and a RATIO of load effect to

resistance for each member checked. The user may choose the

degree of detail in the output data by setting the TRACK

parameter.

2. Member Selection

The user may request that the program search the cold formed steel

shapes database (IS standard sections) for alternative members that

pass the code check and meet the least weight criterion. In

addition, a minimum and/or maximum acceptable depth of the

member may be specified. The program will then evaluate all

database sections of the type initially specified (i.e., channel,

angle, etc.) and, if a suitable replacement is found, presents design

results for that section. If no section satisfying the depth

restrictions or lighter than the initial one can be found, the

program leaves the member unchanged, regardless of whether it

passes the code check or not.

The program calculates effective section properties in accordance

with Clause 5.2.1.1. Cross-sectional properties and overall

slenderness of members are checked for compliance with

Section 9D

9-95

Clause 6.6.3, Maximum Effective Slenderness Ratio for

members in Compression

Clause 5.2.3, Maximum Flat Width Ratios for Elements in

Compression

Clause 5.2.4, Maximum Section Depths.

The program will check member strength in accordance with

Clause 6 of the Standard as follows:

Members in tension

Resistance is calculated in accordance with Clauses 6.1

Members in bending and shear

Resistance calculations are based on Clauses:

a) 6.4.1 Shear stress in webs,

b) 6.4.2 Bending stress in webs

c) 6.4.3 Combined Bending and Shear in Webs.

Members in compression


a) 6.2 Compression on flat unstiffened element,

b) 6.6.1.1 Shapes not subject to torsional-flexural buckling,

c) 6.6.1.2 Singly-symmetric sections and nonsymmetrical

shapes of open cross section or intermittently fastened

singly-symmetrical components of built-up shapes having

Q = 1.0 which may be subject to torsional-flexural

buckling,


Section 9D

9-96

d) 6.6.1.3 Singly-symmetric sections and nonsymmetrical

shapes or intermittently fastened singly-symmetrical

components of built-up shapes having Q < 1.0 which may

be subject to torsional-flexural buckling,

e) 6.8 Cylindrical Tubular Sections.

Members in compression and bending


a) All clauses for members in compression

&

b) 6.3 Laterally Unsupported Members,

c) 6.7.1 Doubly-symmetric shapes or Shapes not subjected

to torsional or torsional-flexural buckling

d) 6.7.2. Singly-symmetric shapes or Intermittently fastened

singly-symmetric components of built-up shapes having

Q=1.0 which may be subjected to torsional-flexural

buckling

e) 6.7.3. Singly-symmetric shapes or Intermittently fastened

singly-symmetric components of built-up shapes having

Q<1.0 which may be subjected to torsional-flexural

buckling.

Input for the coefficients of uniform bending must be provided by

the user.

Section 9D

9-97

The following table contains the input parameters for specifying

values of design variables and selection of design options. Note:

Once a parameter is specified, its value stays at that specified

number till it is specified again. This is the way STAAD works

for all codes.

COLD FORMED STEEL DESIGN PARAMETERS

Parameter

Name

Default

Value Description

BEAM 1.0 When this parameter is set to 1.0 (default), the adequacy of the member is determined by checking a total of 13 equally spaced locations along the length of the member. If the BEAM value is 0.0, the 13 location check is not conducted, and instead, checking is done only at the locations specified by the SECTION command (See STAAD manual for details. For TRUSS members only start and end locations are designed.

CMZ 1.0 Coefficient of equivalent uniform bending z. See IS:801-1975, 6.7. Used for Combined axial load and bending design. Values range from 0.4 to 1.0.

CMY 0.85 Coefficient of equivalent uniform bending y. See IS:801-1975, 6.7. Used for Combined axial load and bending design. Values range from 0.4 to 1.0.

CWY 0.85 Specifies whether the cold work of forming strengthening effect should be included in resistance computation. See IS:801-1975, 6.1.1

Values: 0 – effect should not be included

1 – effect should be included

FLX 1 Specifies whether torsional-flexural buckling restraint is provided or is not necessary for the member. See IS:801-1975, 6.6.1

Values:

0 – Section not subject to torsional flexural buckling 1 – Section subject to torsional flexural buckling


Section 9D

9-98


Parameter

Name

Default

Value Description

FU 450 MPa (4588.72 kg/cm2)

Ultimate tensile strength of steel in current units.

FYLD 353.04 MPa

(3600.0 kg/cm2)

Yield strength of steel in current units.

KX 1.0 Effective length factor for torsional buckling. It is a fraction and is unit-less. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for twisting for determining the capacity in axial compression.

KY 1.0 Effective length factor for overall buckling about the local Y-axis. It is a fraction and is unit-less. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.

KZ 1.0 Effective length factor for overall buckling in the local Z-axis. It is a fraction and is unit-less. Values can range from 0.01 (for a member completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.

LX Member length

Unbraced length for twisting. It is input in the current units of length. Values can range from 0.01 (for a member completely prevented from torsional buckling) to any user specified large value. It is used to compute the KL/R ratio for twisting for determining the capacity in axial compression.

LY Member length

Effective length for overall buckling in the local Y-axis. It is input in the current units of length. Values can range from 0.01 (for a member completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.

Section 9D

9-99


Parameter

Name

Default

Value Description

LZ Member length

Effective length for overall buckling in the local Z-axis. It is input in the current units of length. Values can range from 0.01 (for a member completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the capacity in axial compression.

MAIN 0 0 – Check slenderness ratio

0 – Do not check slenderness ratio

NSF 1.0 Net section factor for tension members DMAX

2540.0 cm. Maximum allowable depth. It is input in the current units of

length.

RATIO 1.0 Permissible ratio of actual to allowable stresses

TRACK 0 This parameter is used to control the level of detail in which the design output is reported in the output file. The allowable values are: 0 - Prints only the member number, section name, ratio, and

PASS/FAIL status. 1 - Prints the design summary in addition to that printed by

TRACK 1 2 - Prints member and material properties in addition to that

printed by TRACK 2. TSA 1 Specifies whether webs of flexural members are adequately

stiffened to satisfy the requirements of IS:801-1975, 5.2.4.

Values:

0 – Do not comply with 5.2.4

1 – Comply with 5.2.4


Section 9D 9-100

13-1

Concrete Design Per SABS 0100-1

13A.1 Design Operations

STAAD has the capability for performing design of concrete

beams and columns according to the South African code SABS

0100-1. The 2000 revision of the code is currently implemented.

Design can be performed for beams (flexure, shear and torsion)

and columns (axial load + biaxial bending). Given the width and

depth (or diameter for circular columns) of a section, STAAD will

calculate the required reinforcement.


The program contains a number of parameters which are needed to

perform and control the design to SABS 0100-1. These parameters

not only act as a method to input required data for code

calculations but give the engineer control over the actual design

process. Default values of commonly used parameters for

conventional design practice have been chosen as the basis. Table

12A.1 contains a complete list of avai lable parameters with their

default values. Note: Once a parameter is specified, its value

stays at that specified number till it is specified again. This is

the way STAAD works for all codes.

Section 13A

South African Concrete Code Per SABS 0100-1

Section 13A

13-2

Table 13A.1 – South African Concrete Design-SABS 0100-1 -Parameters Parameter Default Description Name Value FYMAIN *450 N/mm2 Yield Stress for main reinforcement FYSEC *450N/mm2 Yield Stress for secondary reinforcement a.

Applicable to shear bars in beams FC * 30N/mm2 Concrete Yield Stress / cube strength MINMAIN 8mm Minimum main reinforcement bar size

Acceptable bar sizes: 6 8 10 12 16 20 25 28 32 36 40 50 60

MINSEC 8mm Minimum secondary bar size a. Applicable to shear reinforcement in beams

MAXMAIN 50mm Maximum required reinforcement bar size Acceptable bars are per MINMAIN above.

CLT 20mm Clear Cover for outermost top reinforcement CLB 20mm Clear Cover for outermost bottom

reinforcement CLS 20mm Clear Cover for outermost side

reinforcement TRACK 0.0 0.0 = Critical Moment will not be printed with

beam design report. Column design gives no detailed results. 1.0 = For beam gives min/max steel % and spacing. For columns gives a detailed table of output with additional moments calculated. 2.0 = Output of TRACK 1.0 List of design sag/hog moments and corresponding required steel area at each section of member

WIDTH *ZD Width of concrete member. This value default is as provided as ZD in MEMBER PROPERTIES.

DEPTH *YD Depth of concrete member. This value default is as provided as YD in MEMBER PROPERTIES.

Section 13A

13-3

Table 13A.1 – South African Concrete Design-SABS 0100-1 -Parameters Parameter Default Description Name Value BRACE 0.0 0.0 = Column braced in both directions.

1.0 = Column braced about local Y direction only 2.0 = Column unbraced about local Z direction only 3.0 = Column unbraced in both Y and Z directions

ELY 1.0 Member length factor about local Y direction for column design.

ELZ 1.0 Member length factor about local Z direction for column design.

* Provided in current unit system

13A.3 Member Dimensions

Concrete members that are to be designed by STAAD must have

certain section properties input under the MEMBER PROPERTIES

command. The following example demonstrates the required

input:

UNIT MM

MEMBER PROPERTIES

*RECTANGULAR COLUMN 300mm WIDE X 450mm DEEP

1 3 TO 7 9 PRISM YD 450. ZD 300.

*CIRCULAR COLUMN 300mm diameter

11 13 PR YD 300.

* T-SECTION - FLANGE 1000.X 200.(YD-YB)

* - STEM 250(THICK) X 350.(DEEP)

14 PRISM YD 550. ZD 1000. YB 350. ZB 250.


Section 13A

13-4

In the above input, the first set of members are rectangular

(450mm depth x 300mm width) and the second set of members,

with only depth and no width provided, will be assumed to be

circular with 300mm diameter. Note that area (AX) is not provided

for these members. If shear area areas (AY & AZ ) are to be

considered in analysis, the user may provide them along with YD

and ZD. Also note that if moments of inertias are not provided, the

program will calculate them from YD and ZD. Finally a T section

can be considered by using the third definition above.

13A.4 Beam Design

Beam design includes flexure, shear and torsion. For all types of

beam action, all active beam loadings are scanned to create

moment and shear envelopes and locate the critical sections. The

total number of sections considered is thirteen. From the critical

moment values, the required positive and negative bar pattern is

developed. Design for flexure is carried out as per clause no.

4.3.3.4.

Shear design as per SABS 0100 clause 4.3.4 has been followed and

the procedure includes computation of critical shear values. From

these values, stirrup sizes are calculated with proper spacing. If

torsion is present, the program will also consider the provisions of

SABS 0100 clause 4.3.5. Torsional reinforcement is separately

reported.

Section 13A

13-5

A TRACK 2 design output is presented below .

B E A M N O. 4 D E S I G N R E S U L T S


LENGTH: 7500.0 mm SIZE: 380.0 mm X 715.0 mm COVER: 25.0 mm

DESIGN LOAD SUMMARY (KN MET)

--------------------------------------------------------------------

SECTION |FLEXURE (Maxm. Sagging/Hogging moments)| SHEAR

(in mm) | MZ Load Case MX Load Case | VY P Load Case

--------------------------------------------------------------------

0.0 | 135.75 5 -3.44 5 | 152.06 50.62 4

| -295.92 4 |

625.0 | 189.16 5 -3.43 5 | 133.95 48.87 4

| -236.52 4 |

1250.0 | 231.25 5 -3.41 5 | 115.84 47.12 4

| -188.44 4 |

1875.0 | 262.01 5 -3.40 5 | 97.73 45.37 4

| -151.68 4 |

2500.0 | 281.46 5 -3.39 5 | 79.61 43.63 4

| -126.24 4 |

3125.0 | 289.59 5 -3.37 5 | 61.50 41.88 4

| -112.12 4 |

3750.0 | 286.39 5 -3.36 4 | -62.13 40.13 5

| -109.32 4 |

4375.0 | 271.88 5 -3.37 4 | -80.25 41.88 5

| -117.84 4 |

5000.0 | 246.05 5 -3.39 4 | -98.36 43.63 5

| -137.68 4 |

5625.0 | 208.89 5 -3.40 4 | -116.47 45.37 5

| -168.84 4 |

6250.0 | 160.42 5 -3.41 4 | -134.58 47.12 5

| -211.33 4 |

6875.0 | 100.62 5 -3.43 4 | -152.70 48.87 5

| -265.13 4 |

7500.0 | 29.50 4 -3.44 4 | -170.81 29.63 4

| -330.25 5 |

SUMMARY OF REINF. AREA FOR FLEXURE DESIGN (Sq.mm)

--------------------------------------------------------------------

SECTION | TOP | BOTTOM | STIRRUPS

(in mm) | Reqd./Provided reinf. | Reqd./Provided reinf. | (2 legged)

--------------------------------------------------------------------

0.0 | 1232.70/1256.64( 4-20í )| 543.40/ 565.50( 5-12í )| 8í @ 425 mm

625.0 | 960.90/ 981.74( 2-25í )| 754.32/ 791.70( 7-12í )| 8í @ 510 mm

1250.0 | 751.24/ 791.70( 7-12í )| 937.49/ 942.48( 3-20í )| 8í @ 510 mm

1875.0 | 596.52/ 603.18( 3-16í )| 1075.72/1206.36( 6-16í )| 8í @ 510 mm

2500.0 | 543.40/ 565.50( 5-12í )| 1165.13/1206.36( 6-16í )| 8í @ 510 mm

3125.0 | 543.40/ 565.50( 5-12í )| 1203.00/1206.36( 6-16í )| 8í @ 220 mm

3750.0 | 543.40/ 565.50( 5-12í )| 1188.08/1206.36( 6-16í )| 8í @ 220 mm

4375.0 | 543.40/ 565.50( 5-12í )| 1120.87/1206.36( 6-16í )| 8í @ 220 mm

5000.0 | 543.40/ 565.50( 5-12í )| 1003.50/1005.30( 5-16í )| 8í @ 220 mm

5625.0 | 668.18/ 678.60( 6-12í )| 839.38/ 904.80( 8-12í )| 8í @ 220 mm

6250.0 | 849.99/ 904.80( 8-12í )| 632.84/ 678.60( 6-12í )| 8í @ 220 mm

6875.0 | 1089.94/1206.36( 6-16í )| 543.40/ 565.50( 5-12í )| 8í @ 220 mm

7500.0 | 1397.16/1407.42( 7-16í )| 543.40/ 565.50( 5-12í )| 8í @ 220 mm

--------------------------------------------------------------------

TORSION REINFORCEMENT: Not required


Section 13A

13-6

13A.5 Column Design

Columns are designed for axial force and biaxial bending at the

ends. All active loadings are tested to calculate reinforcement. The

loading which produces maximum reinforcement is called the

critical load and is displayed. The requirements of SABS 0100-1

clause 4.7 are followed, with the user having control on the

effective length in each direction by using the ELZ and ELY

parameters as described in table 12A.1. Bracing conditions are

controlled by using the BRACE parameter. The program will then

decide whether or not the column is short or slender and whether it

requires additional moment calculations. For biaxial bending, the

recommendations of 4.7.4.4 of the code are considered.

Column design is done for square, rectangular and circular

sections. For rectangular and square sections, the reinforcement is

always assumed to be arranged symmetrically. This causes slightly

conservative results in certain cases. Table 12A.3 shows typical

column design results.

Using parameter TRACK 1.0, the detailed output below is

obtained. TRACK 0.0 would merely give the bar configuration,

required steel area and percentage, column size and critical load

case.

Section 13A

13-7

TABLE 12A.3 -COLUMN DESIGN OUTPUT

=======================================================================

C O L U M N N O. 1 D E S I G N R E S U L T S


LENGTH: 3660.0 mm CROSS SECTION: 750.0 mm X 460.0 mm COVER:40.0mm

** GUIDING LOAD CASE: 4 END JOINT: 1 SHORT COLUMN

DESIGN FORCES (KNS-MET)

-----------------------

DESIGN AXIAL FORCE (Pu) : 915.6

About Z About Y

INITIAL MOMENTS : 0.00 0.00

MOMENTS DUE TO MINIMUM ECC. : 18.31 18.31

SLENDERNESS RATIOS : 7.96 4.88

ADDITION MOMENTS (Maddz and Maddy) : 0.00 0.00

TOTAL DESIGN MOMENTS : 555.13 21.91

REQD. STEEL AREA : 3349.20 Sq.mm.

REQD. CONCRETE AREA: 114451.62 Sq.mm.

MAIN REINFORCEMENT : Provide 32 - 12 dia. (1.05%, 3619.20 Sq.mm.)

(Equally Distributed)

TIE REINFORCEMENT : Provide 8 mm dia. rectangular ties @ 140 mm c/c

SECTION CAPACITY BASED ON REINFORCEMENT REQUIRED (KNS-MET)

----------------------------------------------------------

Puz : 2160.42 Muz1 : 570.23 Muy1 : 563.74


Section 13A

13-8

13-9

Steel Design Per SAB Standard SAB0162–1: 1993

13B.1 General

The South African Steel Design facility in STAAD is based on the

SAB Standard SAB0162-1: 1993, Limit States Design of Steel

Structures. A steel section library consisting of South African

Standards shapes is available for member property specification.

The design philosophy embodied in this specification is based on

the concept of limit state design. Structures are designed and

proportioned taking into consideration the limit states at which

they would become unfit for their intended use. Two major

categories of limit-state are recognized - ultimate and

serviceability. The primary considerations in ultimate limit state

design are strength and stability, while that in serviceability is

deflection. Appropriate load and resistance factors are used so that

a uniform reliability is achieved for all steel structures under

various loading conditions and at the same time the chances of

limits being surpassed are acceptably remote.

In the STAAD implementation, members are proportioned to resist

the design loads without exceeding the limit states of strength,

stability and serviceability. Accordingly, the most economic

section is selected on the basis of the least weight criteria as

augmented by the designer in specification of allowable member

depths, desired section type, or other such parameters. The code

checking portion of the program checks whether code requirements

for each selected section are met and identifies the governing

criteria.

Section 13B

South African Steel Code Per SAB Standard SAB0162–1: 1993 Section 13B

13-10

The following sections describe the salient features of the STAAD

implementation of SAB0162-1: 1993. A detailed description of the

design process along with its underlying concepts and assumptions

is available in the specification document.

13B.2 Analysis Methodology

Elastic analysis method is used to obtain the forces and moments

for design. Analysis is done for the primary and combination

loading conditions provided by the user. The user is allowed

complete flexibility in providing loading specifications and using

appropriate load factors to create necessary loading situations.

Depending upon the analysis requirements, regular stiffness

analysis or P-Delta analysis may be specified. Dynamic analysis

may also be performed and the results combined with static

analysis results.

13B.3 Member Property Specifications

For specification of member properties, the steel section library

available in STAAD may be used. The next section describes the

syntax of commands used to assign properties from the built -in

steel table. Member properties may also be specified using the

User Table facility. For more information on these facilities, refer

to the STAAD Technical Reference Manual.

13B.4 Built-in Steel Section Library

The following information is provided for use when the built -in

steel tables are to be referenced for member property specification.

These properties are stored in a database file. If called for, the

properties are also used for member design. Since the shear areas

are built into these tables, shear deformation is always considered

during the analysis of these members.

Section 13B

13-11

I Shapes

The following example illustrates the specification of I- shapes.

1 TO 15 TABLE ST IPE-AA100

H shapes

Designation of H shapes in STAAD is as follows.

For example,

18 TO 20 TABLE ST 152X37UC

PG shapes

Designation of PG shapes in STAAD is as follows.

100 TO 150 TABLE ST 720X200PG

Channel Sections (C & MC shapes)

C and MC shapes are designated as shown in the following

example.

3 TABLE ST 127X64X15C

Double Channels

Back to back double channels, with or without spacing between

them, are specified by preceding the section designation by the

letter D. For example, a back to back double channel section

PFC140X60 without spacing in between should be specified as:


13-12

100 TO 150 TABLE D PFC140X60

A back to back double channel section 140X60X16C with spacing

0.01unitlength in between should be specified as:

100 TO 150 TABLE D 140X60X16C SP 0.01

Note that the specification SP after the section designation is used

for providing the spacing. The spacing should always be provided

in the current length unit.

Angles

To specify angles, the letter L succeeds the angle name. Thus, a

70X70 angle with a 25mm thickness is designated as 70X70X8L.

The following examples illustrate angle specifications.

100 TO 150 TABLE ST 70X70X8L

Note that the above specification is for “standard” angles. In this

specification, the local z-axis (see Fig. 2.6 in the Technical

Reference Manual) corresponds to the Y‟-Y‟ axis shown in the

CSA table. Another common practice of specifying angles assumes

the local y-axis to correspond to the Y‟-Y‟ axis. To specify angles

in accordance with this convention, the reverse angle designation

facility has been provided. A reverse angle may be specified by

substituting the word ST with the word RA. Refer to the following

example for details.

100 TO 150 TABLE RA 45X45X3L

The local axis systems for STANDARD and REVERSE angles are

shown in Fig. 2.6 of the STAAD Technical Reference manual.

Section 13B

13-13

Double Angles

To specify double angles, the specification ST should be

substituted with LD (for long leg back to back) or SD (short leg

back to back). For equal angles, either SD or LD will serve the

purpose. Spacing between angles may be provided by using the

word SP followed by the value of spacing (in current length unit)

after section designation.

100 TO 150 TABLE LD 50X50X3L 3 TABLE LD 40X40X5L SP 0.01

The second example above describes a double angle section

consisting of 40X40X5 angles with a spacing of 0.01 length units.

Tees

Tee sections obtained by cutting W sections may be specified by

using the T specification instead of ST before the name of the W

shape. For example:

100 TO 150 TABLE T IPE-AA180

will describe a T section cut from a IPE-AA180 section.

Rectangular Hollow Sections

These sections may be specified in two possible ways. Those

sections listed in the SAB tables may be specified as follows.

100 TO 150 TABLE ST TUB60X30X2.5


13-14

In addition, any tube section may be specified by using the DT(for

depth), WT(for width), and TH(for thickness) specifications. For

example:

100 TO 150 TABLE ST TUBE TH 3 WT 100 DT 50

will describe a tube with a depth of 50mm, width of 100mm. and a

wall thickness of 3mm. Note that the values of depth, width and

thickness must be provided in current length unit.

Circular Hollow Sections

Sections listed in the SAB tables may be provided as follows:

100 TO 150 TABLE ST PIP34X3.0CHS

In addition to sections listed in the SAB tables, circular hollow

sections may be specified by using the OD (outside diameter) and

ID (inside diameter) specifications.

Pipe symbol

Thickness

PIP34X3.0

Diameter

Width

Tube symbol

Height

Thickness

TUB60X30X2.5

Section 13B

13-15

For example:

100 TO 150 TABLE ST PIPE OD 50 ID 48

will describe a pipe with an outside diameter of 50 length units

and inside diameter of 48 length units. Note that the values of

outside and inside diameters must be provided in terms of current

length unit.

Sample input file to demonstrate usage of South African shapes is

shown below.

STAAD PLANE START JOB INFORMATION ENGINEER DATE 30-Mar-05 END JOB INFORMATION UNIT METER KN JOINT COORDINATES 1 0 0 0; 2 9 0 0; 3 0 6 0; 4 3 6 0; 5 6 6 0; 6 9 6 0; 7 0 10.5 0; 8 9 10.5 0; 9 2.25 10.5 0; 10 6.75 10.5 0; 11 4.5 10.5 0; 12 1.5 11.4 0; 13 7.5 11.4 0; 14 3 12.3 0; 15 6 12.3 0; 16 4.5 13.2 0; MEMBER INCIDENCES 1 1 3; 2 3 7; 3 2 6; 4 6 8; 5 3 4; 6 4 5; 7 5 6; 8 7 12; 9 12 14; 10 14 16; 11 15 16; 12 13 15; 13 8 13; 14 9 12; 15 9 14; 16 11 14; 17 11 15; 18 10 15; 19 10 13; 20 7 9; 21 9 11; 22 10 11; 23 8 10; MEMBER PROPERTY SAFRICAN 1 TABLE ST IPE-AA100 2 TABLE T IPE120 3 TABLE ST 152X23UC 4 TABLE T 152X23UC 5 TABLE ST 812X200PG 6 TABLE T 812X200PG 7 TABLE ST 178X54X15C 8 TABLE D 178X54X15C 9 TABLE D 178X54X15C SP 0.1 10 TABLE ST 25X25X5L 11 TABLE RA 25X25X5L 12 TABLE LD 25X25X5L 13 TABLE SD 25X25X5L 14 TABLE LD 25X25X5L SP 0.1 15 TABLE SD 25X25X5L SP 0.1


13-16

16 TABLE ST TUB40X2.5SHS 17 TABLE ST TUBE TH 0 WT 0 DT 50 18 TABLE ST TUBE TH 0.02 WT 100 DT 50 20 TABLE ST PIP48X2.0CHS 21 TABLE ST PIPE OD 0.5 ID 0.48 PRINT MEMBER PROPERTIES FINISH

13B.5 Section Classification

The SAB specification allows inelastic deformation of section

elements. Thus, local buckling becomes an important criterion.

Steel sections are classified as plastic (Class 1), compact (Class 2),

non compact (Class 3) or slender element (Class 4) sections

depending upon their local buckling characteristics (See Clause

11.2 and Table 1 of SAB0162-1:1993). This classification is a

function of the geometric properties of the section. The design

procedures are different depending on the section class. STAAD

determines the section classification for the standard shapes and

user specified shapes. Design is performed for sections that fall

into the category of Class 1,2 or 3 sections only. Class 4 sections

are not designed by STAAD.

13B.6 Member Resistances

The member resistances are calculated in STAAD according to the

procedures outlined in section 13 of the specification. These

depend on several factors such as members‟ unsupported lengths,

cross-sectional properties, slenderness factors, unsupported width

to thickness ratios and so on. Note that the program automatically

takes into consideration appropriate resistance factors to calculate

member resistances. Explained here is the procedure adopted in

STAAD for calculating the member resistances.

All the members are checked against allowable slenderness ratio as

per Cl.10.2 of SAB0162-1: 1993.

Section 13B

13-17

Axial Tension

The criterion governing the capacity of tension members is based

on two limit states. The limit state of yielding in the gross section

is intended to prevent excessive elongation of the member. The

second limit state involves fracture at the section with the

minimum effective net area. The net section area may be specified

by the user through the use of the parameter NSF (see Table 3B.1).

STAAD calculates the tension capacity of a member based on

these two limits states per Cl.13.2 of SAB0162-1: 1993.

Parameters FYLD, FU and NSF are applicable for these

calculations.

Axial Compression

The compressive resistance of columns is determined based on

Clause 13.3 of the code. The equations presented in this section of

the code assume that the compressive resistance is a function of

the compressive strength of the gross section (Gross section Area

times the Yield Strength) as well as the slenderness factor (KL/r

ratios). The effective length for the calculation of compression

resistance may be provided through the use of the parameters KX,

KY, KZ, LX, LY and LZ (see Table 3B.1). Some of the aspects of

the axial compression capacity calculations are:

1. For frame members not subjected to any bending, and for truss

members, the axial compression capacity in general column

flexural buckling is calculated from Cl.13.3.1 using the

slenderness ratios for the local Y-Y and Z-Z axis. The

parameters KY, LY, KZ and LZ are applicable for this.

2. For single angles, asymmetric or cruciform sections are

checked as to whether torsional-flexural buckling is critical.

But for KL/r ratio exceeding 50,as torsional flexural buckling

is not critical, the axial compression capacities are calculated

by using Cl.13.3. The reason for this is that the South African

code doesn‟t provide any clear guidelines for calculating this

value. The parameters KY, LY, KZ and LZ are applicable for

this.


13-18

3. The axial compression capacity is also calculated by taking

flexural-torsional buckling into account. Parameters KX and

LX may be used to provide the effective length factor and

effective length value for flexural-torsional buckling. Flexural-

torsional buckling capacity is computed for single channels,

single angles, Tees and Double angles.

4. While computing the general column flexural buckling

capacity of sections with axial compression + bending, the

special provisions of 13.8.1(a), 13.8.1(b) and 13.8.1(c) are

applied. For example, Lambda = 0 for 13.8.1(a), K=1 for

13.8.1(b), etc.)

Bending

The laterally unsupported length of the compression flange for the

purpose of computing the factored moment resistance is specified

in STAAD with the help of the parameter UNL. If UNL is less

than one tenth the member length (member length is the distance

between the joints of the member), the member is treated as being

continuously laterally supported. In this case, the moment

resistance is computed from Clause 13.5 of the code. If UNL is

greater than or equal to one-tenth the member length, its value is

used as the laterally unsupported length. The equations of Clause

13.6 of the code are used to arrive at the momen t of resistance of

laterally unsupported members. Some of the aspects of the bending

capacity calculations are:

1. The weak axis bending capacity of all sections except single

angles is calculated as

For Class 1 & 2 sections, Phi*Py*Fy

For Class 3 sections, Phi*Sy*Fy

Where Phi = Resistance factor = 0.9

Py = Plastic section modulus about the local Y axis

Sy = Elastic section modulus about the local Y axis

Fy = Yield stress of steel

Section 13B

13-19

2. For single angles sections are not designed by STAAD, as the

South African code doesn‟t provide any clear guidelines for

calculating this value.

3. For calculating the bending capacity about the Z-Z axis of

singly symmetric shapes such as Tees and Double angles,

SAB0162-1: 1993 stipulates in Clause 13.6(b), page 31, that a

rational method.

Axial compression and bending

The member strength for sections subjected to axial compression

and uniaxial or biaxial bending is obtained through the use of

interaction equations. In these equations, the additional bending

caused by the action of the axial load is accounted for by using

amplification factors. Clause 13.8 of the code provides the

equations for this purpose. If the summation of the left hand side

of these equations exceeds 1.0 or the allowable value provided

using the RATIO parameter (see Table 3B.1), the member is

considered to have FAILed under the loading condition.

Axial tension and bending

Members subjected to axial tension and bending are also designed

using interaction equations. Clause 13.9 of the code is used to

perform these checks. The actual RATIO is determined as the

value of the left hand side of the critical equation.

Shear

The shear resistance of the cross section is determined using the

equations of Clause 13.4 of the code. Once this is obtained, the

ratio of the shear force acting on the cross section to the shear

resistance of the section is calculated. If any of the ratios (for both

local Y & Z axes) exceed 1.0 or the allowable value provided

using the RATIO parameter (see Table 3B.1), the section is

considered to have failed under shear. The code also requires that

the slenderness ratio of the web be within a certain limit (See

Cl.13.4.1.3, page 29 of SABS 0162-1:1993). Checks for safety in

shear are performed only if this value is within the allowable limit.


13-20

Users may by-pass this limitation by specifying a value of 2.0 for

the MAIN parameter.


The design parameters outlined in table below may be used to

control the design procedure. These parameters communicate

design decisions from the engineer to the program and thus allow

the engineer to control the design process to suit an application's

specific needs.

The default parameter values have been selected such that they are

frequently used numbers for conventional design. Depending on

the particular design requirements, some or all of these parameter

values may be changed to exactly model the physical structure.




South African steel design parameters

Parameter

Name


Kt 1.0 K value for flexural torsional buckling

Ky 1.0 K value in local Y-axis, usually minor axis

Kz 1.0 K value in local Z-axis, usually major axis

Lt Member length Length for flexural torsional buckling

Ly Member length Length in local Y axis for slenderness

value KL/r

Lz Member length Length in local Z axis for slenderness value

KL/r

Fyld 300Mpa Yield strength of steel

Fu 345Mpa Ultimate strength of steel

NSF 1.0 Net section factor for tension members

Section 13B

13-21


Parameter

Name


UNT Member Length

Unsupported length in bending

compression of top flange for calculating

moment resistance

UNB Member Length

Unsupported length in bending

compression of bottom flange for

calculating moment resistance

Main 0

Flag for controlling slenderness check

0 - For Check for slenderness.

1 - For Do not check for slenderness

Cb 1.0

Greater than 0.0 and less than 2.5,Value of

Omega_2 (C1.13.6) to be used for

calculation

Equal to 0.0: Calculate Omega_2

Ssy 0

Sidesway parameter

0 - Sideway about local Y-axis.

1 - No sideway about local Y-axis.

Ssz 0

Sidesway parameter

0 - Sideway about local Z-axis.

1 - No sideway about local Z-axis.

Cmy 1.0

1 - Do not calculate Omega-1 for local Y

axis.

2 - Calculate Omega-1 for local Y axis

Cmz 1.0

1 - Do not calculate Omega-1 for local Z

axis.

2 - Calculate Omega-1 for local Z axis

Track 0

Track parameter

0 = Print the design output at the minimum

detail level.

1 = Print the design output at the


13-22


Parameter

Name


intermediate detail level.

2 = Print the design output at maximum

detail level

Dmax 1000 Maximum allowable depth

Dmin 0 Minimum required depth

Ratio 1.0

Permissible ratio of applied load to section

capacity

Used in altering the RHS of critical

interaction equations

Beam 0

0 - Perform design at ends and those

locations specified in the section command.

1 - Perform design at ends and 1/12th

section locations along member length.

Dff 0 Default is 0 indicating that deflection

check is not performed

Dj1 0

Start node of physical member for

determining deflected pattern for deflection

check and should be set along with DFF

parameter

Dj2 0

End node of physical member for

determining deflected pattern for deflection

check and should be set along with DFF

parameter

13B.8 Code Checking

The purpose of code checking is to determine whether the current

section properties of the members are adequate to carry the forces

obtained from the most recent analysis. The adequacy is checked

as per the SAB0162-1: 1993 requirements.

Section 13B

13-23

Code checking is done using forces and moments at specified

sections of the members. If the BEAM parameter for a member is

set to 1 (which is also its default value), moments are calculated at

every twelfth point along the beam. When no section locations are

specified and the BEAM parameter is set to zero, design will be

based on member start and end forces only. The code checking

output labels the members as PASSed or FAILed. In addition, the

critical condition, governing load case, location (di stance from the

start joint) and magnitudes of the governing forces and moments

are also printed. Using the TRACK parameter can control the

extent of detail of the output.

PARAMETER CODE SAB0162 MAIN 1 all LY 4 MEMB 1 LZ 4 MEMB 1 UNL 4 MEMB 1 CB 0 MEMB 1 TO 23 CMZ MEMB 2 1 TO 23 CMY MEMB 2 1 TO 23 SSY 0 MEMB 1 TO 23 SSZ 0 MEMB 1 TO 23 FU 450000 MEMB 1 TO 23 BEAM 1 ALL NSF 0.85 ALL KY 1.2 MEMB 3 4 RATIO 1.0 ALL TRACK 2 ALL FYLD 300000 1 TO 23 CHECK CODE ALL FINISH


13-24

13B.9 Member Selection

The member selection process involves determination of the least

weight member that PASSes the code checking procedure based on

the forces and moments of the most recent analysis. The section

selected will be of the same type as that specified initially. For

example, a member specified initially as a channel will have a

channel selected for it. Selection of members whose properties are

originally provided from a user table will be limited to sections in

the user table. Member selection cannot be performed on members

listed as PRISMATIC.

13B.10 Tabulated Results of Steel Design

Results of code checking and member selection are presented in a

tabular format. The term CRITICAL COND refers to the section of

the SAB0162-1: 1993 specification, which governed the design.

If the TRACK parameter is set to 1.0, the output will be displayed

as follows:

**************************************

STAAD.PRO CODE CHECKING

(SOUTHAFRICAN STEEL/SAB-0162-01(1993))

**************************************

ALL UNITS ARE - KNS MET (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/

FX MY MZ LOCATION

=======================================================================

* 1 ST PFC140X60 (SOUTHAFRICAN SECTIONS)

FAIL SAB-13.9 4.321 1

-20.00 0.00 82.53 0.00

|---------------------------------------------------------------------|

| FACTORED RESISTANCES FOR MEMBER- 1 UNIT - KN,M PHI = 0.90 |

| MRZ= 14.35 MRY= 3.86 |

| CR= 58.41 TR= 425.81 VR= 123.85 |

|---------------------------------------------------------------------|

Factored member resistances will be printed out. Following is a

description of some of the items printed out.

MRZ= Factored moment of resistance in z direction

Section 13B

13-25

MRY= Factored moment of resistance in z direction

CR = Factored compressive resistance for column

TR= Factored tensile capacity

VR= Factored shear resistance

Further details can be obtained by setting TRACK to 2.0. A typical

output of track 2.0 parameter is as follows.

**************************************



**************************************



FX MY MZ LOCATION

=======================================================================

* 1 ST PFC140X60 (SOUTHAFRICAN SECTIONS)

FAIL SAB-13.9 4.321 1

-20.00 0.00 82.53 0.00

MEMBER PROPERTIES (UNIT = CM)

-----------------------------

CROSS SECTION AREA = 1.95E+01 MEMBER LENGTH = 4.50E+02

IZ = 6.05E+02 SZ = 8.64E+01 PZ = 4.24E+02

IY = 6.91E+01 SY = 1.73E+01 PY = 1.52E+02

MATERIAL PROPERTIES (UNIT = MPA)

--------------------------------

FYLD = 248.2 FU = 285.4

SECTION CAPACITIES (UNIT - KN,M)

---------------------------------

CRY = 5.841E+01 CRZ = 2.947E+02

CTORFLX = 2.021E+02

TENSILE CAPACITY = 4.258E+02 COMPRESSIVE CAPACITY = 5.841E+01

FACTORED MOMENT RESISTANCE : MRY = 3.859E+00 MRZ = 1.435E+01

FACTORED SHEAR RESISTANCE : VRY = 1.238E+02 VRZ = 1.168E+02

MISCELLANEOUS INFORMATION

--------------------------

NET SECTION FACTOR FOR TENSION = 1.000

KL/RY = 239.051 KL/RZ = 80.789 ALLOWABLE KL/R = 300.000

UNSUPPORTED LENGTH OF THE COMPRESSION FLANGE (M) = 4.500

OMEGA-1 (Y-AXIS) = 1.00 OMEGA-1 (Z-AXIS) = 1.00 OMEGA-2 = 1.00

SHEAR FORCE (KNS) : Y AXIS = 0.000E+00 Z AXIS = 3.526E+01

SLENDERNESS RATIO OF WEB (H/W) = 2.00E+01


13-26

Following is a description of some of the items printed out.

CRY Factored compressive resistance for column buckling

about the local y axis

CRZ Factored compressive resistance for column buckling

about the local z axis

CTORFLX Factored compressive resistance against torsional

flexural buckling

TENSILE

CAPACITY

Factored tensile capacity

COMPRESSIVE

CAPACITY

Factored compressive capacity

FACTORED MOMENT

RESISTANCE

MRY = Factored moment of resistance in y direction

MRZ = Factored moment of resistance in z direction

FACTORED SHEAR

RESISTANCE

VRY = Factored shear resistance in y direction

VRZ = Factored shear resistance in z direction

13B.11 Verification Problems

In the next few pages are included 3 verification examples for

reference purposes.

Section 13B

13-27

Verification Problem No. 1

Objective: - To determine the capacity of a South African I-

section column in axial compression. Column is

braced at its ends for both axes.

Design Code: - South African steel design code (SAB:0162-

1(1993))

Reference: - Example 4.3.4.1, page 4.18, Structural Steel

Design to SAB:0162-1(1993)(Limit state Design)

by Greg Parrott, 1st edition, Shades Technical

publication

Given: - FYLD = 300Mpa

Length = 6000mm

Comparison: -

Solution Design Strength (kN)

Theory 1516

STAAD 1516

Difference No


13-28

****************************************************

* *

* STAAD.Pro *

* Version Bld *

* Proprietary Program of *

* Research Engineers, Intl. *

* Date= *

* Time= *

* *

* USER ID: *

****************************************************

1. STAAD PLANE

2. START JOB INFORMATION

3. ENGINEER DATE

4. END JOB INFORMATION

5. INPUT WIDTH 79

6. ***********************************************

7. * STAAD.PRO GENERATED COMMENT *

8. ***********************************************

9. *1 0 0 0,2 0 6 0

10. ***********************************************

11. UNIT METER KN

12. JOINT COORDINATES

13. 1 0 0 0; 2 0 6 0

14. MEMBER INCIDENCES

15. 1 1 2

16. MEMBER PROPERTY SAFRICAN

17. 1 TABLE ST 356X67UB

18. DEFINE MATERIAL START

19. ISOTROPIC MATERIAL1

20. E 2.0E+008

21. POISSON 0.3

22. DENSITY 76.977

23. ISOTROPIC STEEL

24. E 2.00E+008

25. POISSON 0.3

26. DENSITY 76.8195

27. ALPHA 1.2E-005

28. DAMP 0.03

29. END DEFINE MATERIAL

30. UNIT MMS KN

31. CONSTANTS

32. MATERIAL STEEL MEMB 1

33. UNIT METER KN

34. SUPPORTS

35. 1 FIXED

36. LOAD 1 LOADTYPE NONE TITLE LOAD CASE 1

37. JOINT LOAD

38. 2 FY -1500

39. PERFORM ANALYSIS

P R O B L E M S T A T I S T I C S

-----------------------------------

NUMBER OF JOINTS/MEMBER+ELEMENTS/SUPPORTS = 2/ 1/ 1

ORIGINAL/FINAL BAND-WIDTH= 1/ 1/ 3 DOF

TOTAL PRIMARY LOAD CASES = 1, TOTAL DEGREES OF FREEDOM = 3

SIZE OF STIFFNESS MATRIX = 0 DOUBLE KILO-WORDS

REQRD/AVAIL. DISK SPACE = 12.0/ 3978.5 MB

40. PARAMETER

41. CODE SAB0162

42. LZ 6 ALL

43. LY 3 ALL

44. FU 450000 ALL

45. BEAM 1 ALL

46. NSF 0.85 ALL

47. TRACK 2 ALL

48. FYLD 300000 ALL

49. CHECK CODE ALL

Section 13B

13-29

**************************************



**************************************



FX MY MZ LOCATION

=======================================================================

1 ST 356X67UB (SOUTHAFRICAN SECTIONS)

PASS SAB-13.8 0.989 1

1500.00 0.00 0.00 0.00


-----------------------------


IZ = 1.95E+04 SZ = 1.07E+03 PZ = 1.21E+03

IY = 1.36E+03 SY = 1.57E+02 PY = 2.43E+02


--------------------------------

FYLD = 300.0 FU = 345.0


---------------------------------

CRY = 1.516E+03 CRZ = 2.038E+03

CTORFLX = 1.516E+03





--------------------------







50. FINISH


13-30


Objective:- To determine the capacity of a South African I-section

beam in bending. The beam has torsional and simple

lateral rotational restraint at the supports, and the

applied point load provides effective lateral restraint at

the point of application is braced at its ends for both

axes.

Design Code: - South African steel design code (SAB:0162-

1(1993))

Reference: - Example 4.5, page 4.37, Structural Steel Design to

SAB:0162-1(1993)(Limit state Design) by Greg Parrott,

1st edition, Shades Technical publication


Comparison: -

Solution Design Strength (kN-m)

Theory 353.4

STAAD 353.3

Difference Small

Section 13B

13-31

****************************************************

* *

* STAAD.Pro *

* Version Bld *



* Date= *

* Time= *

* *

* USER ID: *

****************************************************

1. STAAD PLANE


3. ENGINEER DATE


5. INPUT WIDTH 79

6. UNIT METER KN


8. 1 0 0 0; 2 10 0 0; 3 7 0 0


10. 1 1 3; 2 3 2


12. 1 2 TABLE ST 406X67UB



15. E 2.0E+008

16. POISSON 0.3

17. DENSITY 76.977

18. ISOTROPIC STEEL

19. E 2.00E+008

20. POISSON 0.3

21. DENSITY 76.8195

22. ALPHA 1.2E-005

23. DAMP 0.03


25. UNIT MMS KN

26. CONSTANTS

27. MATERIAL STEEL MEMB 1 2

28. UNIT METER KN

29. SUPPORTS

30. 1 3 PINNED


32. MEMBER LOAD

33. 1 CON GY -104 4

34. 1 UNI GY -26.4

35. 2 UNI GY -7.2



-----------------------------------






37. PARAMETER

38. CODE SABS0162

39. CB 0 ALL

40. UNL 4 MEMB 1

41. FU 450000 ALL

42. BEAM 1 ALL

43. NSF 0.85 ALL

44. FYLD 300000 ALL

45. TRACK 2 ALL

46. CHECK CODE MEMB 1


13-32

**************************************



**************************************



FX MY MZ LOCATION

=======================================================================

1 ST 406X67UB (SOUTHAFRICAN SECTIONS)

PASS SHEAR 0.244 1

0.00 0.00 32.40 7.00


-----------------------------


IZ = 2.43E+04 SZ = 1.19E+03 PZ = 1.35E+03

IY = 1.36E+03 SY = 1.52E+02 PY = 2.37E+02


--------------------------------

FYLD = 300.0 FU = 345.0


---------------------------------

CRY = 4.532E+02 CRZ = 2.016E+03

CTORFLX = 4.532E+02





--------------------------





SHEAR FORCE (KNS) : Y AXIS = 0.000E+00 Z AXIS = -1.565E+02


47. FINISH

Section 13B

13-33


Objective: - To determine the elastic shear capacity of a South

African I-section which is simply supported over the

span of 8 m

Design Code: - South African steel design code (SAB:0162-1(1993))

Reference: - Example 4.6.5, page 4.54, Structural Steel Design to

SAB:0162-1(1993)(Limit state Design) by Greg Parrott,

1st edition, Shades Technical publication


Comparison: -

Solution Design Strength (kN)

Theory 687.1

STAAD 687.1

Difference No


13-34

****************************************************

* *

* STAAD.Pro *

* Version Bld *



* Date= *

* Time= *

* *

* USER ID: *

****************************************************

1. STAAD PLANE


3. ENGINEER DATE


5. INPUT WIDTH 79

6. UNIT METER KN


8. 1 0 0 0; 2 8 0 0


10. 1 1 2


12. 1 TABLE ST 457X67UB



15. E 2E+008

16. POISSON 0.3

17. DENSITY 76.977

18. ISOTROPIC STEEL

19. E 2E+008

20. POISSON 0.3

21. DENSITY 76.8195

22. ALPHA 1.2E-005

23. DAMP 0.03


25. UNIT MMS KN

26. CONSTANTS

27. MATERIAL STEEL MEMB 1

28. UNIT METER KN

29. SUPPORTS

30. 1 2 PINNED


32. MEMBER LOAD

33. 1 UNI GY -70



-----------------------------------






35. PARAMETER

36. CODE SABS0162

37. FU 450000 ALL

38. BEAM 1 ALL

39. FYLD 300000 ALL

40. TRACK 2 ALL

41. CHECK CODE ALL

Section 13B

13-35

**************************************



**************************************



FX MY MZ LOCATION

=======================================================================

* 1 ST 457X67UB (SOUTHAFRICAN SECTIONS)

FAIL CLASS 4 SECT 2.000

0.00 0.00 0.00


-----------------------------


IZ = 2.94E+04 SZ = 1.30E+03 PZ = 1.47E+03

IY = 1.45E+03 SY = 1.53E+02 PY = 2.37E+02


--------------------------------

FYLD = 300.0 FU = 345.0


---------------------------------

CRY = 0.000E+00 CRZ = 0.000E+00

CTORFLX = 0.000E+00





--------------------------







42. FINISH


13-36

Section 14

American Aluminum Code

14-1

Design Per American Aluminum Code

14.1 General

STAAD is currently equipped with the facilities to perform design

based on the specifications for Aluminum Structures. The

requirements of the Allowable Stress Design, Sixth edition,

October 1994, have been implemented.

The various issues related to the implementation of this code in

STAAD are explained below.

14.2 Member Properties

In order to do this design in STAAD, the members in the structure

must have their properties specified from Section VI of the above-

mentioned manual. The section names are mentioned in Tables 5

through 28 of that manual. All of those tables except Table 10

(Wing Channels) and Table 20 (Bulb Angles) are available in

STAAD.

Described below is the command specification for various

sections:

Standard single section

memb-list TA ST section-name

Section 14


Section 14

14-2

Example

1 TO 5 TA ST CS12X11.8

9 TA ST I8.00X13.1

11 33 45 67 TA ST LS8.00X8.00X0.625

18 TA ST 1.50PipeX160

15 TA ST T(A-N)6.00X8.00X11.2

23 25 29 TA ST 20X12RectX.500Wall

Double channel back-to-back

memb-list TA BACK section-name SPACING value

Example

3 TA BACK C(A-N)7X3.61 SPACING 1.5

5 TA BACK C15X17.33 SP 0.75

Double channel front-to-front

memb-list TA FRONT section-name SPACING value

Example

2 TA FRONT CS12X10.3 SP 1.0

4 TA FR CS10X10.1 SP 0.5

Section 14

14-3

Double angle long leg back-to-back

memb-list TA LD section-name SPACING value

Example

14 TA LD LS4.00X3.00X0.375 SP 1.5

Double angle short leg back-to-back

memb-list TA SD section-name SPACING value

Example

12 TA SD L3.5X3X0.5 SP 0.25

13 TA SD L8X6X0.75 SP 1.0

14.3 Design Procedure

The design is done according to the rules specified in Sections 4.1,

4.2 and 4.4 on pages I-A-41 and I-A-42 of the Aluminum code.

The allowable stresses for the various sections are computed

according to the equations shown in Section 3.4.1 through 3.4.21

on pages I-A-27 through I-A-40. The adequacy of the member is

checked by calculating the value of the left -hand side of equations

4.1.1-1, 4.1.1-2, 4.1.1-3, 4.1.2-1, 4.4-1 and 4.4-2. This left-hand

side value is termed as RATIO. If the highest RATIO among these

equations turns out to be less than or equal to 1.0, the member is

declared as having PASSed. If it exceeds 1.0, the member has

FAILed the design requirements.


Section 14

14-4

The check for torsion per Clause 4.3 for open sections is currently

not done.

14.4 Design Parameters

The following are the parameters for specifying the values for

variables associated with the design. Note: Once a parameter is

specified, its value stays at that specified number till it is

specified again. This is the way STAAD works for all codes.

Table 14.1 Aluminum Design Parameters

Parameter Default Description

Name Value

ALLOY 34 This variable can take on a value from 1 through 40. The default value represents the alloy 6061-T6. See Table 12A.2 in the following pages for a list of values for this parameter and the alloy they represent. Table 3.3-1 in Section I-B of the Aluminum specifications provides information on the properties of the various alloys.

PRODUCT 1 This variable can take on a value from 1 through 4. They represent: 1 - All 2 - Extrusions 3 - Drawn Tube 4 - Pipe The default value stands for All. The PRODUCT parameter finds mention in Table 3.3-1 in Section I-B of the Aluminum specifications.

ALCLAD 0 This variable can take on a value of either 0 or 1. 0 - Material used in the section is not an Alclad. 1 - Material used in the section is an Alclad.

Section 14

14-5



Name Value

WELD 0 In Table 3.4-2 in Section I-A of the Aluminum specifications, it is mentioned that the value of coefficients Kt and Kc are dependent upon whether or not, the location of the section where design is done is within 1.0 inch of a weld. The WELD parameter is used in STAAD for this purpose. The values that can be assigned to this parameter are: 0 - Region is farther than 1.0in from a weld 1 - Region is within 1.0in from a weld

STRUCTURE 1 In Table 3.4-1 in Section I-A of the Aluminum specifications, it is mentioned that the value of coefficients nu, ny and na are dependent upon whether the structure being designed is a building or a bridge. Users may convey this information to STAAD using the parameter STRUCTURE. The values that can be assigned to this parameter are: 1 - Buildings and similar type structures 2 - Bridges and similar type structures

DMAX 1000 in. Maximum depth permissible for the section during member selection. This value must be provided in the current units.

DMIN 0.0 in Minimum depth required for the section during member selection. This value must be provided in the current units.

UNL Member length

Distance between points where the compression flange is braced against buckling or twisting. This value must be provided in the current units. This value is used to compute the allowable stress in bending compression.

KY 1.0 Effective length factor for overall column buckling in the local Y-axis. It is a fraction and is unit-less. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the allowable stress in axial compression.


Section 14

14-6



Name Value

LY Member length

Effective length for overall column buckling in the local Y-axis. It is input in the current units of length. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the allowable stress in axial compression.

KZ 1.0 Effective length factor for overall column buckling in the local Z-axis. It is a fraction and is unit-less. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the allowable stress in axial compression.

LZ Member length

Effective length for overall column buckling in the local Z-axis. It is input in the current units of length. Values can range from 0.01 (for a column completely prevented from buckling) to any user specified large value. It is used to compute the KL/R ratio for determining the allowable stress in axial compression.

KT 1.0 Effective length factor for torsional buckling. It is a fraction and is unit-less. Values can range from 0.01 (for a column completely prevented from torsional buckling) to any user specified large value. It is used to compute the KL/R ratio for twisting for determining the allowable stress in axial compression. See Equation 3.4.7.2-6 on page I-A-28 of the Aluminum specifications for details.

LT Member length

Unbraced length for twisting. It is input in the current units of length. Values can range from 0.01 (for a column completely prevented from torsional buckling) to any user specified large value. It is used to compute the KL/R ratio for twisting for determining the allowable stress in axial compression. See Equation 3.4.7.2-6 on page I-A-28 of the Aluminum specifications for details.

STIFF Member length

Spacing in the longitudinal direction of shear stiffeners for stiffened flat webs. It is input in the current units of length. See section 3.4.21 on page I-A-40 of the Aluminum specifications for information regarding this parameter.

Section 14

14-7



Name Value

SSY 0.0 Factor that indicates whether or not the structure is subjected to sidesway along the local Y axis of the member. The values are: 0 - Sidesway is present along the local Y-axis of the member 1 - There is no sidesway along the local Y-axis of the member. The sidesway condition is used to determine the value of Cm explained in Section 4.1.1, page I-A-41 of the Aluminum specifications.

SSZ 0.0 Factor that indicates whether or not the structure is subjected to sidesway along the local Z axis of the member. The values are: 0 - Sidesway is present along the local Z-axis of the member 1 - There is no sidesway along the local Z-axis of the member. The sidesway condition is used to determine the value of Cm explained in Section 4.1.1, page I-A-41 of the Aluminum specifications.

TRACK 2 This parameter is used to control the level of detail in which the design output is reported in the output file. The allowable values are: 1 - Prints only the member number, section name,

ratio, and PASS/FAIL status. 2 - Prints the design summary in addition to that

printed by TRACK 1 3 - Prints the member properties and alloy properties in addition to that printed by TRACK 2. 4 - Prints the values of variables used in design in

addition to that printed by TRACK 3.


Section 14

14-8



Name Value

BEAM 0.0 If this parameter is set to 1.0, the adequacy of the member is determined by checking a total of 13 equally spaced locations along the length of the member. If the BEAM value is 0.0, the 13 location check is not conducted, and instead, checking is done only at the locations specified by the SECTION command (See STAAD manual for details). If neither the BEAM parameter nor any SECTION command is specified, STAAD will terminate the run and ask the user to provide one of those 2 commands. This rule is not enforced for TRUSS members.

14.5 Code Checking

The purpose of code checking is to determine whether the initially

specified member properties are adequate to carry the forces

transmitted to the member due to the loads on the structure. Code

checking is done at the locations specified by either the SECTION

command or the BEAM parameter described above.

It is done with the aid of the command “CHECK CODE”

described in the main STAAD Technical Reference Manual.

Example Problem 1 in the Getting Started and Examples Manual

for STAAD provides an example on the usage of the CHECK

CODE command.

14.6 Member Selection

The member selection process involves the determination of the

least weight member that PASSes the code checking procedure

based on the forces and moments of the most recent analysis. The

section selected will be of the same type as that specified initially.

For example, a member specified initially as a channel will have a

channel selected for it. It is done with the aid of the command

“SELECT MEMBER” described in the main STAAD Technical

Section 14

14-9

Reference Manual. Example Problem 1 in the Getting Started and

Examples Manual for STAAD provides an example on the usage of

the SELECT MEMBER command.

Sample input data for Aluminum Design

PARAMETER

CODE ALUMIMUM

BEAM 1 ALL

KY 1.2 MEMB 3 4

ALLOY 35 ALL

PRODUCT 2 ALL

TRACK 3 ALL

SELECT ALL

ALCLAD 1 ALL

STRUCT 1 ALL

CHECK CODE ALL


Section 14

14-10

Table 14.2 - ALLOY PARAMETER :

Values and Corresponding Names

1 1100-H12

2 1100-H14

3 2014-T6

4 2014-T6510

5 2014-T6511

6 2014-T651

7 3003-H12

8 3003-H14

9 3003-H16

10 3003-H18

11 3004-H32

12 3004-H34

13 3004-H36

14 3004-H38

15 5005-H12

16 5005-H14

17 5005-H32

18 5005-H34

19 5050-H32

20 5050-H34

21 5052-H32

22 5052-H34

23 5083-H111

24 5086-H111

25 5086-H116

26 5086-H32

27 5086-H34

28 5454-H111

29 5454-H112

30 5456-H111

31 5456-H112

32 6005-T5

33 6105-T5

Section 14

14-11

34 6061-T6

35 6061-T6510

36 6061-T6511

37 6061-T651

38 6063-T5

39 6063-T6

40 6351-T5


Section 14

14-12

Section 15

American Transmission Tower Code

15-1

Steel Design per ASCE 10-97

15A.1 General Comments

The design of structural steel members in accordance with the

specifications of ASCE Standard 10-97 – Design of Latticed Steel

Transmission Structures is now implemented. This code is meant

to supercede the older edition of the code, available under the

name ASCE Publication 52. However, in the interests of backward

compatibility, both codes are currently accessible in STAAD.Pro.

To access the ASCE 52 code, use the commands

PARAMETER CODE ASCE 52

To access the ASCE 10-97 code, use the commands

PARAMETER CODE ASCE

In general, the concepts followed in MEMBER SELECTION and

CODE CHECKING procedures are similar to that of the AISC

based design. It is assumed that the user is familiar with the basic

concepts of steel design facilities available in STAAD. Please

refer to Section 2 of the STAAD Technical Reference Manual for

detailed information on this topic. This section specifically

addresses the implementation of steel design based on ASCE 10-

97.

Design is available for all standard sections listed in the AISC

ASD 9th

edition manual, namely, Wide Flanges, S, M, HP, Tees,

Channels, Single Angles, Double Angles, Tubes and Pipes. Design

Section 15A

Steel Design Per ASCE 10-97

Section 15A

15-2

of HSS sections (those listed in the 3 rd edition AISC LRFD

manual) and Composite beams (I shapes with concrete slab on top)

is not suppported.

15A.2 Allowable Stresses per ASCE 10 - 97

Member selection and code checking operations in th e STAAD

implementation of ASCE 10-97 are done to resist loads at stresses

approaching yielding, buckling, fracture and other limiting

conditions specified in the standard. Those stresses are referred to

in the standard as Design Stresses. The appropriate sections of the

ASCE standard where the procedure for calculating the design

stresses is explained are as follows.

Design Axial Tensile Stress

Design tensile stresses are calculated on the basis of the procedure

described in section 3.10. The NSF parameter (see the Parameters

table shown later in this section) may be used if the section area

needs to be reduced to account for bolt holes.

Design Axial Compressive Stress

Design compressive stress calculation is based on the procedures

of section 3.6 through 3.9. For angle members under compression,

the procedures of sections 3.7 and 3.8 have been implemented.

Capacity of the section is computed for column buckling and

wherever applicable, torsional buckling. The user may control the

effective lengths for buckling using the LT, LY, LZ and/or KT,

KY, KZ parameters (see the Parameters table shown later in this

section).

Design Bending Compressive Stress

Calculations for design bending compressive stress about the

major axis and minor axis are based on the procedures of section

3.14. Procedures outlined in sections 3.14.1 through 3.14.6 have

been implemented.

Section 15A

15-3

Design Bending Tensile Stress

Calculations for design bending tensile stress about the major and

minor axis are based on the procedures of section 3.14.2.

Design Shear Stress

Calculation of the design shear stress is based on the procedure

outlined in section 3.15 of the ASCE 10-97. The procedure of

section 3.15.2 is followed for angles and the procedure of section

3.15.1 is followed for all other sect ions.

15A.3 Critical Conditions used as criteria to determine Pass/Fail status

These are Clause 3.4 for slenderness limits, Clause 3.12 for Axial

Compression and Bending, Clause 3.13 for Axial Tension and

Bending, Clause 3.9.2 for Maximum w/t ratios and Clause 3.15 for

Shear.


Design per ASCE (10-97) must be initiated by using the command

CODE ASCE. This command should be the first command after the

PARAMETER statement. Other applicable parameters are

summarized in the table shown later in this section. These

parameters may be used to control the design process to suit

specific modeling needs. The default parameter values have been

selected such that they are frequently used numbers for

conventional design.

15A.5 Code Checking and Member Selection

Both code checking and member selection options are available in

the ASCE 10-97 implementation. For general information on these


Section 15A

15-4

options, refer to sections 2 and 5 of the STAAD Technical

Reference Manual.

Table of Steel Design Parameters for ASCE 10-97

Parameter Name

Default Value

Description

KY 1.0 Effective length factor (K) for compression buckling about the Y-axis (minor axis)

KZ 1.0 Effective length factor (K) for compression buckling about the Z-axis (major axis)

KT 1.0 Effective length coefficient for warping restraint (clause 3.14.4, pg 11)

LY Member Length

Length to calculate slenderness ratio for buckling about the Y-axis (minor axis)

LZ Member Length

Length to calculate slenderness ratio for buckling about the Z-axis (major axis)

LT Member Length

Effective length for warping.

FYLD 36.0 KSI Yield Strength of steel NSF 1.0 Net section factor for tension members UNL Member

Length Unsupported length of member for calculation of allowable bending stress

UNF 1.0 Same as UNL, but provided as a fraction of the member length

TRACK 0.0 0.0 = Suppresses printing of allowable stresses 1.0 = Prints all allowable stresses

DMAX 45.0 in. Maximum allowable depth for member selection DMIN 0.0 in. Minimum allowable depth for member selection RATIO 1.0 Permissible ratio that determines the cut off point for

pass/fail status. A value below this quantity indicates PASS while a value greater than this quantity indicates FAILURE.

BEAM 1.0 0.0 = Perform design at beam ends and section locations specified according to the SECTION command 1.0 = Perform design at the ends and eleven

intermediate sections of the beam

Section 15A

15-5


Parameter Name

Default Value

Description

MAIN 2 Parameter that indicates the member type for the purpose of calculating the KL/R ratio (SEE CLAUSE 3.4, PAGE 3, ASCE 10-97) = 10 : DO NOT PERFORM THE KL/R CHECK = 1 : LEG MEMBER KL/R <= 150 = 2 : COMPRESSION MEMBER KL/R <= 200 = 3 : TENSION MEMBER KL/R <= 500 = 4 : HANGAR MEMBERS KL/R <= 375 (Clause 4C.4, page 43) = 5 : REDUNDANT MEMBERS KL/R <= 250

ELA 4 Indicates what type of end conditions are to be used from among Equations 3.7-4 thru 3.7-7 to determine the KL/R ratio. ELA=1 : EQN.3.7-4, Page 4

(VALID FOR LEG MEMBERS ONLY) ELA=2 : EQN.3.7-5, Page 4 ELA=3 : EQN.3.7-6, Page 4 ELA=4 : EQN.3.7-7, Page 5

ELB 1 Indicates what type of end conditions are to be used from among Equations. 3.7-8 thru 3.7-10 and 3.7-12 thru 3.7-14 to determine the KL/R ratio. ELB=1 : EQN.3.7-8, Page 5, EQN.3.7-12, Page 5 ELB=2 : EQN.3.7-9, Page 5, EQN.3.7-13, Page 5 ELB=3 : EQN.3.7-10, Page 5, EQN.3.7-14,Page 5


Section 15A

15-6


Parameter Name

Default Value

Description

LEG 0.0 This parameter is meant for plain angles. 0.0 = indicates that the angle is connected by both legs and allowable stress in axial tension is 1.0FYLD. 1.0 = indicates that the angle is connected only by the shorter leg and allowable tensile stress is computed per clause 3.10.2 as 0.9FYLD. 2.0 = indicates that the angle is connected by the longer leg.

DBL 0.75 in. Diameter of bolt for calculation of number of bolts required and the net section factor.

FYB 36 KSI Yield strength of bolt. FVB 30 KSI Shear strength of bolt. NHL

0 Number of bolt holes on the cross section that should be used to determine the net section factor for tension capacity.

Notes:

All values must be provided in the current unit system.

Once a parameter is specified, its value stays at that specified number

till it is specified again. This is the way STAAD works for all codes.

15-7

Steel Design per ASCE Manuals and Reports

15B.1 General Comments

This document presents some general statements regarding the

implementation of the Steel Design per ASCE Manuals and

Reports on Engineering Practice No. 52 – Guide for Design of

Steel Transmission Towers, Second Edition. The design

philosophy and procedural logistics for member selection and code

checking is based upon the principles of allowable stress design.

Two major failure modes are recognized: failure by overstressing

and failure by stability considerations.

The following sections describe the salient features regarding the

process of calculation of the relevant allowable stresses and the

stability criteria being used. Members are proportioned to resist

the design loads without exceeding the allowable stresses and the

most economical section is selected based on the least weight

criteria. The code checking part of the program also checks the

slenderness requirements, the minimum metal thickness

requirements and the width-thickness requirements. It is generally

assumed that the user will take care of the detailing requirements

like provision of stiffeners and check the local effects like flange

buckling, web crippling, etc. It general, it may be noted that the

concepts followed in MEMBER SELECTION and CODE

CHECKING procedures are similar to that of the AISC based

design. It is assumed that the user is familiar with the basic

concepts of Steel Design facilities available in STAAD. Please

refer to Section 3 of the STAAD Technical Reference Manual for

detailed information on this topic. This document specifically

addresses the implementation of steel design based on ASCE Pub.

52.

Section 15B

Steel Design Per ASCE Manuals and Reports

Section 15B

15-8

15B.2 Allowable Stresses per ASCE (Pub. 52)

The member design and code checking in the STAAD

implementation of ASCE (Pub. 52) is based upon the allowable

stress design method. Appropriate sections of this publication are

referenced below.

Allowable Axial Tensile Stress

Allowable tensile stresses are calculated on the basis of the

procedure described in section 4.10. The NSF parameter (Table

1.1) may be used if the net section area needs to be used.

Allowable Axial Compressive Stress

Allowable compressive stress calculation is based on the

procedures of section 4.6 through 4.9. For angle members under

compression, the procedures of sections 4.7 and 4.8 have been

implemented. Capacity of the section is computed for column

buckling and wherever applicable, torsional buckling. The user

may control the effective lengths for buckling using the LX, LY,

LZ and/or KX, KY, KZ parameters (Table 1.1).

Allowable Bending Compressive Stress

Calculations for allowable bending compressive stress about the

major axis and minor axis are based on the procedures of section

4.14. Procedures outlined in sections 4.14.1 through 4.14.6 have

been implemented.

Allowable Bending Tensile Stress

Calculations for allowable bending tensile stress about the major

and minor axis are based on the procedures of section 4.14.2.

Allowable Shear Stress

Calculation of the allowable shear stress is based on the procedure

outlined in section 4.15 of the ASCE Pub. 52. The procedure of

Section 15B

15-9

section 4.15.2 is followed for angles and the procedure of section

4.15.1 is followed for all other sections.

Critical Conditions used as criteria to determine Pass/Fail

status

These are Clause 4.4 for slenderness limits, Equation 4.12-1 for

Axial Compression and Bending, Equation 4.13-1 for Axial

Tension and Bending, Clause 4.9.2 for Maximum w/t ratios and

Clause 4.15 for Shear.


Design per ASCE (Pub. 52) must be initiated by using the

command CODE ASCE. This command should be the first

command after the PARAMETER statement. Other applicable

parameters are summarized in Table 1.1. These parameters may be

used to control the design process to suit specific modeling needs.


frequently used numbers for conventional design.

15B.4 Code Checking and Member Selection

Both code checking and member selection options are available in

the ASCE Pub. 52 implementation. For general information on

these options, refer to section 3 of the STAAD Technical

Reference Manual. For information on specification of these

commands, refer to section 6.


Section 15B

15-10

15B.5 Parameter Definition Table

Table 15B.1 - Steel Design Parameters for ASCE (PUB. 52) Based Design

Parameter Name

Default Value

Description

KY 1.0 Effective length factor (K) for compression buckling about the Y-axis (minor axis)

KZ 1.0 Effective length factor (K) for compression buckling about the Z-axis (major axis)

KT 1.0 Effective length coefficient for warping restraint (clause 4.14.4, pg 36)

LY Member Length

Length to calculate slenderness ratio for buckling about the Y-axis (minor axis)

LZ Member Length

Length to calculate slenderness ratio for buckling about the Z-axis (major axis)

LT Member Length

Effective length for warping.

FYLD 36.0 KSI Yield Strength of steel NSF 1.0 Net section factor for tension members UNL Member

Length Unsupported length of member for calculation of allowable bending stress

UNF 1.0 Same as UNL, but provided as a fraction of the member length

TRACK 0.0 1.0 = Suppresses printing of allowable stresses 1.0 = Prints all allowable stresses

DMAX 45.0 in. Maximum allowable depth for member selection DMIN 0.0 in. Minimum allowable depth for member selection RATIO 1.0 Permissible ratio that determines the cut off point for

pass/fail status. A value below this quantity indicates PASS while a value greater than this quantity indicates FAILURE.

Section 15B

15-11


Parameter Name

Default Value

Description

BEAM 0.0 2.0 = Perform design using the section locations specified according to the SECTION command 3.0 = Perform design at the ends and eleven intermediate sections of the beam

MAIN 2 Parameter that indicates the member type for the purpose of calculating the KL/R ratio (SEE CLAUSE 4.4, PAGE 25) = 10 : DO NOT PERFORM THE KL/R CHECK = 1 : LEG MEMBER KL/R <= 150 = 2 : COMPRESSION MEMBER KL/R <= 200 = 3 : TENSION MEMBER KL/R <= 500 = 4 : HANGAR MEMBERS KL/R <= 375 (Clause 4C.4, page 43) = 5 : REDUNDANT MEMBERS KL/R <= 250

ELA 4 Indicates what type of end conditions are to be used From among Equations 4.7-4 thru 4.7-7 to determine the the KL/R ratio. ELA=1 : EQN.4.7-4, Page 26

(VALID FOR LEG MEMBERS ONLY) ELA=2 : EQN.4.7-5, Page 27 ELA=3 : EQN.4.7-6, Page 27 ELA=4 : EQN.4.7-7, Page 27

ELB 1 Indicates what type of end conditions are to be used From among Equations. 4.7-8 thru 4.7-10 to determine the KL/R ratio. ELB=1 : EQN.4.7-8, Page 27, EQN.4.7-12, Page 28 ELB=2 : EQN.4.7-9, Page 27, EQN.4.7-13, Page 28 ELB=3 : EQN.4.7-10, Page 27, EQN.4.7-14,Page28


Section 15B

15-12


Parameter Name

Default Value

Description

LEG 0.0 This parameter is meant for plain angles. 3.0 = indicates that the angle is connected by both legs and allowable stress in axial tension is 1.0FYLD. 4.0 = indicates that the angle is connected only by the shorter leg and allowable tensile stress is computed per clause 4.10.2 as 0.9FYLD. 5.0 = indicates that the angle is connected by the longer leg.

DBL 0.75 in. Diameter of bolt for calculation of number of bolts required and the net section factor.

FYB 36 KSI Yield strength of bolt. FVB 30 KSI Shear strength of bolt. NHL

0 Number of bolt holes on the cross section that should be used to determine the net section factor for tension capacity.

Notes:

All values must be provided in the current unit system.


specified number till it is specified again. This is the way STAAD

works for all codes.

Section 16

American Steel Design Per A.P.I. Code

16-1

Steel Design Per A.P.I.

16.1 Design Operations

STAAD contains a broad set of facilities for the design of

structural members as individual components of an analyzed

structure. The member design facilities provide the user with the

ability to carry out a number of different design operations. These

facilities may be used selectively in accordance with the

requirements of the design problem. The operations to perform a

design are:

Specify the members and the load cases to be considered in the

design;

Specify whether to perform code checking or member

selection;

Specify design parameter values, if different from the default

values; and

Specify design parameters to carry out punching shear checks.

These operations may be repeated by the user any number of times

depending upon the design requirements, but care should be taken

when coupled with manipulation of the punching shear LEG

parameter.

The basic process is:-

a. Define the STAAD model geometry, loading and analysis.

b. Define the API code parameters with LEG 1.0.

c. Run the analysis and API design which creates the Geometry

file and give preliminary design results.

d. Check and modify the Geometry file as necessary.

Section 16


Section 16

16-2

e. Reset the LEG parameter to 2.0 and re-run the analysis to read

the modified Geometry file for the final design results.

16.2 Allowables per API Code

For steel design, STAAD compares the actual stresses with the

allowable stresses as defined by the American Petroleum Institute

(API-RP2A) Code. The 20th edition of API Code, as published in

1993, is used as the basis of this design (except for tension stress).

16.2.1 Tension Stress

Allowable tension stresses, as calculated in STAAD, are based on

the API Code, clause (3.2.1-1).

Allowable tension stress on the net section

Ft = 0.60Fy

16.2.2 Shear Stress

Beam Shear Stress

Allowable beam shear stress on the gross section must conform to

(3.2.4-2):

Fv = 0.4 Fy

The maximum applied beam shear stress is:

fv = V / 0.5 A (3.2.4-1)

Torsional Shear Stress

Allowable torsional shear stress

Fvt = 0.4 Fy (3.2.4-4)

Section 16

16-3

Fvt is the maximum torsional shear stress per (3.2.4-3).

16.3 Stress due to Compression

The allowable compressive stress on the gross section of axially

loaded compression members is calculated based on the formula

3.2.2-1 in the API Code, when the largest effective slenderness

ratio

r

Kl is less than Cc =

yF

E22 . If r

Kl exceeds Cc the

allowable compressive stress is increased as per formula (3.2.2 -2)

of the Code.

For t

D > 60 the lesser of Fxe or Fxc are substituted for Fxy .

Fxe = the elastic local buckling stress calculated with C, the critical

elastic buckling coefficient = 0.3 (3.2.2-3)

Fxc = the inelastic local buckling stress, (3.2.2-4)

16.4 Bending Stress

The allowable bending stress for tension and compression for a

symmetrical member loaded in the plane of its minor axis, as given

in Section 3.2.3 is:

a) Fb = 0.75 Fy

provided t

D

yF

1500 (Imperial Units)

b) Fb =

Et

DFy74.184.0 Fy


Section 16

16-4

where

yF

1500 <

t

D <

yF

3000 (Imperial Units)

c) Fb =

Et

DFy58.072.0 Fy

where

yF

3000 <

t

D 300 (Imperial Units)

16.5 Combined Compression and Bending

Members subjected to both axial compression and bending stresses

are proportioned to satisfy API formula 3.3.1-1 and 3.3.1-2 when

a

a

F

f is greater than 0.15, otherwise formula 3.3.1-3 applies. It

should be noted that during code checking or member selection, if

a

a

F

f exceeds unity, the program does not compute the second

3.3.1-1/2.

16.6 Design Parameters

The program contains a large number of parameter names which

are required to perform design and code checks. These parameter

names, with their default values, are listed in Table 12.1. These

parameters communicate design decisions from the engineer to the

program. (Also see section 5.44.1).


frequently used numbers for conventional design. Depending on

the particular design requirements for an analysis, some or all of

these parameter values may have to be changed to exactly model

the physical structure. For example, by default the KZ value (k

value in local z-axis) of a member is set to 1.0, wile in the real

Section 16

16-5

structure it may be 1.5. In that case, the KZ value in the program

can be changed to 1.5, as shown in the input instruction (Section

5). Similarly, the TRACK value of a member is set to 0.0, which

means no allowable stresses of the member will be printed. If the

allowable stresses are to be printed, the TRACK value must be set

to 1.0.

Notes: The parameter names DMAX and DMIN are only used for

member selection. Once a parameter is specified, its value stays at

that specified number till it is specified again. This is the way


Table 16.1- American (API) Steel Design Parameters

Parameter

Name

Default

Value

Description



LY Member Length

Length in local Y-axis to calculate slenderness ratio.

LZ Member Length

Length in local Z-axis to calculate slenderness ratio.

FYLD 36 KSI Yield strength of steel.

NSF 1.0 Net section factor for tension members.

UNL Member Length

Unsupported length for calculating allowable bending stress

UNF 1.0 Same as above provided as a fraction of actual member length

CB 1.0 Cb value as used in Section 1.5 of AISC 0.0 = Cb value to be calculated Any other value will mean the value to be used in design

MAIN 0.0 1.0 = Main member

2.0 = Secondary member

SSY 0.0 0.0 = Sidesway in local y-axis


Section 16

16-6

Table 16.1- American (API) Steel Design Parameters

Parameter

Name

Default

Value

Description

1.0 = No sidesway

SSZ 0.0 Same as above except in local z-axis

CMY

CMZ

0.85 for sidesway*

and calculated for no sidesway

Cm value in local y & z axes

TRACK 0.0 1.0 = Print all critical member stresses

100.0 = Suppress all checks except punching shear

DMAX 0.0 Maximum allowable depth

DMIN 0.0 Minimum allowable depth

RATIO Permissible ratio of the actual to allowable stresses

WELD 1 for closed sections

2 for open sections

Weld type, as explained in section 3.1.1.

1 = Welding is one side only except for wide flange or tee sections, where the web is always assumed to be welded on both sides.

2 = Welding is both sides. For closed sections like pipe or tube, the welding will be only on one side.

BEAM 1.0 0.0 = design only for end moments or those at locations specified by the SECTION command.

= calculate moments at twelfth points along the beam, and use the maximum Mz location for design.

WMIN 1.16 in. Minimum thickness

WSTR 0.4 X FLYD Allowable welding stress

LEG 1.0

2.0

To write out external parameters file.

To read in the external parameters file.

Section 16

16-7

16.7 Code Checking

The purpose of code checking is to ascertain whether the provided

section properties of the members are adequate as per API. Code

checking is done using the forces and moments at specific sections

of the members. If no sections are specified, the program uses the

start and end forces for code checking.

When code checking is selected, the program calculates and prints

whether the members have passed or failed the checks, the critical

condition of API code (like any of the API specifications for

compression, tension, shear, etc.), the value of the ratio of the

critical condition (overstressed for value more than 1.0 or an y

other specified RATIO value), the governing load case, and the

location (distance from the start of the number of forces in the

member) where the critical condition occurs.

Code checking can be done with any type of steel section listed in

Section 2.2, American Steel Design, of the Technical Reference

manual.

16.8 Member Selection



select the most economical section, i.e. the lightest section which

fulfills the code requirements for the specified member. The

section selected will be of the same type section as originally

designated for the member being designed. Member selection can

also be constrained by the parameters DMAX and DMIN which

limits the maximum and minimum depth of the members.

Member selection can be performed with all types of hollow steel

sections.


Section 16

16-8

Selection of members whose properties are originally input from a

user created table will be limited to sections in the user table.

Member selection cannot be performed on members whose section

properties are input as prismatic.

16.9 Truss Members

As mentioned earlier, a truss member is capable of carrying only

axial force. So in design, no time is wasted calcula ting the

allowable bending or shear stresses, thus reducing design time

considerably. Therefore, if there is any truss member in an

analysis (like bracing or strut, etc.), it is wise to declare it as a

truss member rather than as a regular frame member wi th both

ends pinned.

16.10 Punching Shear

For tubular members, punching shear may be checked in

accordance with the American Petroleum Institute (API) RP 2A –

20th Edition Section 4. The parameter PUNCH is used to identify

joint types for each end of the member where the punching shear

check is required. The PUNCH parameter is only read in from the

external geometry file. The external geometry file is described in

section 12.13. The PUNCH parameter is not specified within the

STAAD input file (the file with the .std extension).

Type of Joint and Geometry Req. Value of Parameter

PUNCH

K (overlap) 1.0

K (gap) 2.0

T & Y 3.0

CROSS 4.0

CROSS (with/diaphragms) 5.0

Section 16

16-9

Note: A value representing joint type and geometry must be

provided for parameter PUNCH, in the external file. On the first

run where no external table is present, LEG must equal 1.0.

16.11 Generation of the Geometry File

Automatic selection of the chord and brace members is performed

with the parameter LEG 1.0.

Two tubular members are used by the program to identify the

chord member. The chord members must be collinear (5 degree

tolerance).

The chord member must have a greater diameter and thickness

than the brace member being considered.

The punching shear check is performed on the joint treating it as a

T/Y joint. The yield stress of the brace is used. In the 50%

strength check the brace and chord yield are assumed to be the

same.

The major moment axis Mz is taken as In Plane Bending (IPB).

To change this, the parameter SWAP 1 should be used in the

external geometry file.

Note: The in-plane/out-of-plane correspondence can be set by

using the BETA angle.

If the punching shear cannot be performed at the joint for the

member being considered, a message is written to the output file

<filename>.ANL.

If a punching shear check is performed with the parameter LEG

1.0 used, then the geometry data used to perform the check is

written to the default external output file APIPUN.

The default external output/input file name can be changed by

using the command line:-


Section 16

16-10

CODE API <filename>.

This external output data file can be edited and used as an external

input file to re-perform the check using the parameter PUNCH 1.0

to 5.0.

This external input file allows can/stub geometry data to be

specified and chords to be assigned geometry where they could not

be identified in the Automatic selection.

The parameter LEG 2.0 must be used to read an external input file

where the default name is APIPUN.

The yield strength of the brace is used in the punching shear

check. This can be changed in the external geometry file. The

user should ensure that the correct cord member has been selected

for the check.

16.12 Chord Selection and Qf Parameter

Qf is a factor to account for the presence of nominal longitudinal

stress in the chord. When calculating Q f for the joints, the

moments used in the chord stress calculation will be from the

computer node results and not the representative moments

underneath the brace. If the moment varies significantly a long the

chord, it is more accurate to use the actual chord moment in the

middle of the brace foot print. The tests reported in Reference I1

were performed with a constant moment along the chord. Thus for

a local joint check, the local chord moment (under the brace)

should be used.

STAAD calculates Qf based on the moment at the chord member.

The chord member can be selected automatically by initial

screening by the program (based on geometry and independent of

loading) or specified by the user in the External file.

1 Ref I: Boone, TJ, Yura, JA and Hoadley, PW, Ultimate Strength if Tubular Joints – Chord

Stress Effects, OTC 4828, 1984

Section 16

16-11

In the automatic selection of the chord two collinear members (5

degree tolerance) are used to identify the chord. The chord is then

selected from one of the two members based on the larger diameter

then thickness or then by the minimum framing angle; for T joints

the first member modeled will be selected as the chord.

The user should confirm that the chord either be assigned by the

program or the user is representative of the local chord moment for

the brace in question.

16.13 External Geometry File

An example of the external geometry file is shown below:

BRACE CHORD PUNCH D T d T GAP FYLD THETAT TW SWAP

209 211 3 17.992 0.984 12.752 0.787 0.000 50.00 0.00 0.000 0

209 210 3 17.992 0.984 12.752 0.787 0.000 50.00 0.00 0.000 0

212 202 3 17.992 0.787 12.752 0.787 0.000 50.00 0.00 0.000 0

The parameters used in the external file are defined as follows:

Table 16.2 – External File

Parameter Description

PUNCH Parameter for punching shear (See Section 12.10)

BRACE Member number of brace CHORD Member number of chord D Chord Diameter in inches T Chord Thickness in inches d Brace Diameter in inches T Brace Thickness in inches GAP Gap in inches (must be negative for overlap

K-joint) FYLD Local yield strength used for joint in KIPS THETAT Angle of through brace in overlap K-joint in


Section 16

16-12

Table 16.2 – External File

Parameter Description

Degrees TW Used in overlap K-joint, taken as the lesser of

the weld throat thickness or thickness t of the thinner brace in inches

SWAP If parameter SWAP 0 is used then major moment Mz is taken for In Plane Bending (IPB). SWAP 1 uses the minor moment My as the IPB.

Notes:

For overlap K-joints, the through brace is assumed to be the

same diameter as the brace being checked.

If any of the parameters for diameter and thickness specified

in the external file are less than that for members being

checked, then the member properties specified in the STAAD

file shall be used.

The member diameter and thickness should be used in API

equation (4.1-1); in this check it has been assumed that the

yield strength of the chord and brace members are the same. The geometry file name is currently limited to eight characters

(4 if an extension as .txt is used).

The overall process of performing punching shear checks consists

of two steps. These steps are explained in section 12.16.

16.14 Limitations

The parameter SELECT 1.0 should not be used while carrying out

punching shear checks. It can be used in initial runs for member

selection.

No classification of the joint is performed using the loading.

No hydrostatic checks are performed.

Section 16

16-13

16.15 Tabulated Results of Steel Design

For code checking or member selection, the program produces the

results in a tabulated fashion. The items in the output table are

explained as follows:

a) Member refers to the member number for which the

design is performed.

b) TABLE refers to AISC steel section name which has been

checked against the steel code or has been selected.

c) RESULTS prints whether the member has PASSed or

FAILed. If the RESULT is FAIL, there will be an asterisk

(*) mark on front of the member.

d) CRITICAL COND refers to the section of the AISC code

which governs the design.

e) RATIO prints the ratio of the actual stresses to allowable

stresses for the critical condition. Normally a value of 1.0

or less will mean the member has passed.

f) LOADING provides the load case number which governed

the design.

g) FX, MY, and MZ provide the axial force, moment in local

Y-axis, and the moment in local Z-axis respectively.

Although STAAD does consider all the member forces

and moments (except torsion) to perform design, only FX,

MY and MZ are printed since they are the ones which are

of interest, in most cases.

h) LOCATION specifies the actual distance from the start of

the member to the section where design forces govern.

i) If the parameter TRACK is set to 1.0, the program will

block out part of the table and will print the allowable

bending stressed in compression (FCY & FCZ) and

tension (FTY & FTZ), allowable axial stress in

compression (FA), and allowable shear stress (FV).


Section 16

16-14

16.16 The Two-Step Process

The overall procedure for performing the code check per the API

code is as follows:

Step 1 – Creating the geometry data file. This is done by

specifying the name of the geometry data file alongside the

command line CODE API. If a file name is not specified, STAAD

automatically assigns the file name APIPUN to the geometry data

file. The parameter instructions in the .std file should contain the

LEG parameter and it should be assigned the value 1.0.

Example Reading External Geometry File

UNIT INCHES KIPS

PARAMETERS

* All joint data will be written to external file GEOM1 for

punching shear.

CODE API GEOM1

LEG 1.0

* Joints to be considered as T and Y, i.e. PUNCH is set to 3.0.

FYLD 50.0 ALL

TRACK 1.0 ALL

RATIO 1.0 ALL

BEAM 1.0 ALL

CHECK CODE ALL

After ensuring that your STAAD input file contains the above

data, run the analysis. Once the analysis is completed, you will

find that a file by the name GEOM1 has been created and is

located in the same folder as the one where your .std file is

located. (In case you did not specify a file name - GEOM1 shown

in the earlier example - STAAD will create the file named

APIPUN.

Section 16

16-15

Step 2 – The geometry data file (GEOM 1 or otherwise) should be

inspected and modified as required such as changing the PUNCH

values and local section properties for the punching shear checks.

Modify the .std file so it reruns the code check process by reading

the instructions of the GEOM file. This message is conveyed by

changing the value of the LEG parameter to 2.0. After making this

change, a re-analysis will result in the program using the

information in the geometry data file (GEOM1, APIPUN, or

otherwise) for performing the code check.

Example Reading an existing Joint Geometry Data File,

GEOM1

UNIT INCHES KIPS

PARAMETERS

* All joint data will be read from the external file GEOM1 for

punching shear.

CODE API GEOM1

LEG 2.0

FYLD 50.0 ALL

TRACK 1.0 ALL

RATIO 1.0 ALL

BEAM 1.0 ALL

CHECK CODE ALL


Section 16

16-16

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