staad training - module 3 - malaybalay city june 2011_2

OUTLINEOUTLINE

1.1. INTRODUCTIONINTRODUCTION

2.2. BEAM DESIGNBEAM DESIGN2.1. FLEXURE2.1. FLEXURE

2.2. SHEAR & TORSION2.2. SHEAR & TORSION

2.3. DESIGN FOR ANCHORAGE2.3. DESIGN FOR ANCHORAGE

2.4. STAAD PRO INPUT PARAMETERS2.4. STAAD PRO INPUT PARAMETERS

2.5. STAD DESIGN OUTPUT FOR BEAMS2.5. STAD DESIGN OUTPUT FOR BEAMS

2.6. SEISMIC REQUIREMENTS FOR BEAMS2.6. SEISMIC REQUIREMENTS FOR BEAMS

OUTLINEOUTLINE

3. COLUMN DESIGN3. COLUMN DESIGN3.1. COLUMN INTERACTION DIAGRAM3.1. COLUMN INTERACTION DIAGRAM

3.2. STAAD DESIGN BRIEF FOR COLUMNS 3.2. STAAD DESIGN BRIEF FOR COLUMNS

3.3. STAAD DESIGN OUTPUT FOR 3.3. STAAD DESIGN OUTPUT FOR

COLUMNSCOLUMNS

3.4 SEISMIC REQUIREMENTS FOR 3.4 SEISMIC REQUIREMENTS FOR

COLUMNSCOLUMNS

4. CONCLUSION4. CONCLUSION

1. INTRODUCTION1. INTRODUCTION

Analysis part is always followed by the Analysis part is always followed by the

design part.design part.

However, it must be noted that the initial However, it must be noted that the initial

proportioning of beam and column sizes proportioning of beam and column sizes

is part of the design and may not be the is part of the design and may not be the

final dimension. final dimension.

Thus the Thus the design is a series of iteration design is a series of iteration

and resizingand resizing, then reanalysis, then , then reanalysis, then

redesign.redesign.

Design is an iteration process:Design is an iteration process:

1.1. Initial sizing of beams and columns.Initial sizing of beams and columns.

2.2. Analysis for stresses.Analysis for stresses.

3.3. Design of steel reinforcements.Design of steel reinforcements.

if design is inadequate, repeat step if design is inadequate, repeat step

1, 2, and 3.1, 2, and 3.

4. 4. If design is adequate, adopt sizes If design is adequate, adopt sizes

and reinforcements.and reinforcements.


All concrete design calculation is All concrete design calculation is

governed by the current ACI 318 code.governed by the current ACI 318 code.

Unified (strength) design method is Unified (strength) design method is

adopted by the current code.adopted by the current code.

The working stress design (WSD) is The working stress design (WSD) is

deleteddeleted from the ACI 318 codefrom the ACI 318 code

STAAD Pro STAAD Pro do not do not employ the WSD for employ the WSD for

reinforced concrete design.reinforced concrete design.


SPECIAL MOMENT RESISTING FRAMES SPECIAL MOMENT RESISTING FRAMES

(SMRF) (SMRF) are the type of frames, instead of are the type of frames, instead of

ORDINARY MOMENT RESISTING ORDINARY MOMENT RESISTING

FRAMES (OMRF) FRAMES (OMRF) are required for high are required for high

seismic risk areas, such as the seismic risk areas, such as the

Philippines.Philippines.

Therefore, the NSCP requires that all Therefore, the NSCP requires that all

buildings in the Philippines must be buildings in the Philippines must be

designed to effectively designed to effectively resist high resist high

seismic forces.seismic forces.


At the moment, STAAD Pro has At the moment, STAAD Pro has

NO provisionNO provision for automatic for automatic

seismic detailing in reinforced seismic detailing in reinforced

concrete design.concrete design.

What shall we do????What shall we do????


FLEXUREFLEXURE

SHEARSHEAR

TORSIONTORSION

22. . BEAM DESIGNBEAM DESIGN

2.1. FLEXURE2.1. FLEXURE

The main (longitudinal) reinforcement is The main (longitudinal) reinforcement is

calculated for calculated for midspanmidspan (sagging) and (sagging) and

support (hogging) bending moments on support (hogging) bending moments on

the basis of the section profile in the the basis of the section profile in the

design brief (design brief (ieie. PRISMATIC ZD, YD). . PRISMATIC ZD, YD).



CRITICAL SAGGING MOMENT

CRITICAL HOGGING MOMENT

CRITICAL HOGGING MOMENT

ZONE 1 ZONE 2 ZONE 3



TheThe STAAD Pro does not have any limit STAAD Pro does not have any limit

of any bars in any one layer as long as of any bars in any one layer as long as

the spacing requirements specified in the spacing requirements specified in

the code are satisfied.the code are satisfied.

TheThe program can handle a maximum of program can handle a maximum of

four layers of reinforcement, two layers four layers of reinforcement, two layers

each at the top and bottom.each at the top and bottom.



TheThe actual amount of steel required as actual amount of steel required as

well as the maximum and minimum well as the maximum and minimum

required for required for flexure is shown as ROW, flexure is shown as ROW,

ROWMX AND ROWMIN, respectively.ROWMX AND ROWMIN, respectively.

It is important to note that the beams are It is important to note that the beams are

designed for flexural MZ only. The designed for flexural MZ only. The

moment My is not considered in the moment My is not considered in the

design.design.

bh x

MY

y

MZ

Top bars

(max of 2 layers)



bottom bars

(max of 2 layers)



d

d

SFACE

OR

EFACE

BEAM ELEMENT LINE

COLUMN ELEMENT LINE

SHEAR FORCE AND TORSIONAL

MOMENT LOCATION CALCULATED

STEEL REINFORCEMENTS



When required, torsional reinforcement in

the form of closed stirrups or hoop

reinforcement must be provided.


2.2. SHEAR & TORSION 2.2. SHEAR & TORSION



In addition to the stirrups, longitudinal

steel bars are provided in corners of the

stirrups and are well distributed around

the section


2.2. SHEAR & TORSION 2.2. SHEAR & TORSION

In the ACI Code, the design for torsion is In the ACI Code, the design for torsion is

based on space truss analogy.based on space truss analogy.

After After torsionaltorsional cracking occurs, the cracking occurs, the

torque is resisted by closed stirrups, torque is resisted by closed stirrups,

longitudinal bars, and concrete longitudinal bars, and concrete

compression diagonals.compression diagonals.


2.3. DESIGN FOR ANCHORAGE2.3. DESIGN FOR ANCHORAGE

In STAAD output for flexural design, the

anchorage requirement is shown with a

YES or NO at the START and END of the

beam. The designer must provide the

details of anchorage.

4db

5db

6db

4db or 2.5 min

D

PPPPWWRRPPPP'' GGEEPPPPPPPPPPPP'' GGEEPPPPPPPP'' GGEE

++RRRRNNLLIIDDQQFFKKRRUULLVV

2.42.4. . STAAD PRO INPUT PARAMETERSSTAAD PRO INPUT PARAMETERS

Parameter Default Value Description

FYMAIN * 60,000 psi (414 MPa) Yield Stress for main reinforcing

steel

FYSEC * 60,000 psi (414 MPa) Yield Stress for Secondary Steel

FC * 4,000 psi (28 MPa) Compressive Strength of

Concrete

CLT *1.5 inch (37.5 mm) Clear cover for top

reinforcement

CLB *1.5 inch (37.5 mm) Clear cover for bottom

reinforcement

CLS *1.5 inch (37.5 mm) Clear cover for side

reinforcement

MINMAIN** #4 (12mm) Min main reinforcement bar size

MINSEC ** #4 (12mm) Min secondary reinforcement

bar size

MAXMAIN ** #18 (57 mm) Max main reinforcement bar size

NSECTION*** 12 Number of equally-spaced sections to be considered

in finding critical moments for beam design.

TRACK 0.0 BEAM DESIGN:

With TRACK set to 0.0, critical moments will not be

printed out with beam design report.

A value of 1.0 will mean a print out.

A value of 2.0 will print out required steel areas for al

intermediate sections specified by NSECTION.

COLUMN DESIGN:

TRACK 0.0 prints out detailed design results.

TRACK 1.0 prints out column interaction analysis

results in addition to TRACK 0.0 output.

TRACK 2.0 prints out schematic interaction diagram

and intermediate interaction values in addition to all

of the above.

RHOMN 0.01

(1%)

Minimum reinforcement required in a concrete

column. ACI code allows 1% to 8%.

2.42.4. . STAAD PRO INPUT PARAMETERSSTAAD PRO INPUT PARAMETERS

UNIT KN METERUNIT KN METER

START CONCRETE DESIGNSTART CONCRETE DESIGN

CODE ACI 2002CODE ACI 2002

FYMAIN 414 ALLFYMAIN 414 ALL

MAXMAIN 20 ALLMAXMAIN 20 ALL

CLB 40MMCLB 40MM

DESIGN BEAM 17 10DESIGN BEAM 17 10

END CONCRETE DESIGNEND CONCRETE DESIGN

EXAMPLE EXAMPLE

DESIGN BRIEF FOR BEAMSDESIGN BRIEF FOR BEAMS

nn In STAAD Pro V8i (SELECT Series 1), In STAAD Pro V8i (SELECT Series 1),

three versions of the ACI Code are three versions of the ACI Code are

implemented: 1999, 2002, and 2005implemented: 1999, 2002, and 2005

nn To access any of the code editions, To access any of the code editions,

specify the commandsspecify the commands

START CONCRETE DESIGNSTART CONCRETE DESIGN

CODE ACI 1999 CODE ACI 1999 (for 1999)(for 1999)

or CODE ACI 2002 or CODE ACI 2002 (for 2002) (for 2002)

or CODE ACI or CODE ACI (for 2005)(for 2005)

EXAMPLE EXAMPLE

DESIGN BRIEF FOR BEAMSDESIGN BRIEF FOR BEAMS

BEAM NO. 97 DESIGN RESULTS BEAM NO. 97 DESIGN RESULTS -- FLEXURE PER CODE ACI FLEXURE PER CODE ACI 318318--0505LEN LEN -- 5000. MM FY 5000. MM FY -- 275. FC 275. FC -- 21. MPA, SIZE 21. MPA, SIZE -- 300. X 400. MMS300. X 400. MMSLEVEL HEIGHT BAR INFO FROM TO ANCHORLEVEL HEIGHT BAR INFO FROM TO ANCHOR(MM) (MM) (MM) STA END(MM) (MM) (MM) STA END__________________________________________________________________________________________________________________1 54. 5 1 54. 5 -- 12MM 802. 3989. NO 12MM 802. 3989. NO NONO2 342. 4 2 342. 4 -- 20MM 0. 1484. YES NO20MM 0. 1484. YES NO3 342. 4 3 342. 4 -- 20MM 3308. 5000. NO YES20MM 3308. 5000. NO YES____________________________________________________________________________________________________________________

Check the output if ACI318-05 to comply with NSCP 2010

Override these values Override these values if longitudinal if longitudinal reinforcement for reinforcement for torsion is requiredtorsion is required.

2.5. SAMPLE STAAD BEAM DESIGN OUTPUT2.5. SAMPLE STAAD BEAM DESIGN OUTPUT

B E A M N O. 97 D E S I G N R E S U L T S - SHEAR

AT START SUPPORT - Vu= 68.16 KNS Vc= 81.19 KNS Vs= 9.70

KNS

Tu= 0.34 KN-MET Tc= 2.9 KN-MET Ts= 0.0 KN-MET LOAD 4

NO STIRRUPS ARE REQUIRED FOR TORSION.

REINFORCEMENT IS REQUIRED FOR SHEAR.

PROVIDE 10 MM 2-LEGGED STIRRUPS AT 178. MM C/C FOR 2158. MM

ADDITIONAL LONGITUDINAL STEEL REQD. FOR TORSIONAL

RESISTANCE = 0.00 SQ.CM.

AT END SUPPORT - Vu= 70.66 KNS Vc= 81.19 KNS Vs= 13.03 KNS

Tu= 0.34 KN-MET Tc= 2.9 KN-MET Ts= 0.0 KN-MET LOAD 4

NO STIRRUPS ARE REQUIRED FOR TORSION.

REINFORCEMENT IS REQUIRED FOR SHEAR.

PROVIDE 10 MM 2-LEGGED STIRRUPS AT 178. MM C/C FOR 2158. MM

ADDITIONAL LONGITUDINAL STEEL REQD. FOR TORSIONAL

RESISTANCE = 0.00 SQ.CM.

2.5. OUTPUT 2.5. OUTPUT OF BEAM DESIGN OF BEAM DESIGN

((SHEAR and TORSION)SHEAR and TORSION)

This is not final. This is not final.

To be checked To be checked

against seismic against seismic

provisionsprovisions

Since the Philippines is located in a high Since the Philippines is located in a high

seismic risk region, adopting the seismic risk region, adopting the SMRFSMRF

((SSpecial pecial MMoment oment RResisting esisting FFrame) rame) is a is a

must. must.

Therefore, a special detailing for Therefore, a special detailing for

seismic requirement shall is required. seismic requirement shall is required.

Unfortunately, STAAD Pro at the Unfortunately, STAAD Pro at the

moment does not have the facility for moment does not have the facility for

seismic detailing.seismic detailing.

2.62.6. . SEISMIC REQUIREMENTS FOR BEAMSSEISMIC REQUIREMENTS FOR BEAMS

At this point the design output of STAAD At this point the design output of STAAD

Pro is compliant to ACI Code 318Pro is compliant to ACI Code 318--08 or 08 or

the NSCP 2010, the NSCP 2010, EXCEPT FOR THE EXCEPT FOR THE

SEISMIC DETAILING requirements.SEISMIC DETAILING requirements.


Flexural Flexural Members shall satisfy the following:Members shall satisfy the following:

(ACI (ACI 318318--08 Section 21.3.1 08 Section 21.3.1 or NSCP or NSCP 421.5.1421.5.1))

1. Clear span shall not be less than four (4)

times the effective depth.

2. The width-to-depth ratio , b/d, shall not be

less 0.3.

3. The width shall not be less than 250mm

4. The width, bs, of the supporting member

plus distances on each side of the

supporting member not exceeding of

the depth of the flexural member.


1.1. Longitudinal reinforcement for both Longitudinal reinforcement for both

top and bottom steel (A) should be in top and bottom steel (A) should be in

the range defined as follows:the range defined as follows:

Longitudinal reinforcement requirements

(ACI code Section 21.3.2 / NSCP 421.5.1)

3 fc' bd

fy

200 bd

fy

A 0 025 bd,

2. 2. The positive moment strength at joint The positive moment strength at joint

face should be greater or equal the face should be greater or equal the

negative moment strength at the face negative moment strength at the face

of the jointof the joint



MnL-

MnL+ 1/2 (MnL

- )

MnR-

MnR+ 1/2 (MnR

- )

3. 3. Neither the negative nor the positive Neither the negative nor the positive

moment strength in any section along the moment strength in any section along the

member should be less than the member should be less than the

maximum strength provided at the face maximum strength provided at the face

of either joint.of either joint.



MnL-

max

Many section 1/4 (MnL-

max )

4.4. Lap splices of flexural reinforcement are Lap splices of flexural reinforcement are

permitted only if hoop reinforcement is permitted only if hoop reinforcement is

provided over the lap length.provided over the lap length.

Maximum spacing of transverse Maximum spacing of transverse reinfreinf

enclosing the lapped bars shall not enclosing the lapped bars shall not

exceed 100mm. exceed 100mm.



Lap splices shall not be used:Lap splices shall not be used:

a.a. Within the joint.Within the joint.

b.b. With a distance of twice the member With a distance of twice the member

depth from the face of the joint; anddepth from the face of the joint; and

c.c. At locations where analysis indicates At locations where analysis indicates

flexural yielding (flexural yielding (ieie. Location of plastic . Location of plastic

hinges)hinges)



2h 2h 2h 2h

h

Yield may occur1.

Transverse reinforcement requirements


For SMRF, plastic hinges will form at the For SMRF, plastic hinges will form at the

ends of flexural members. Those ends of flexural members. Those

locations should be specially detailed to locations should be specially detailed to

ensure sufficient ductility.ensure sufficient ductility.

2. Spacing of hoops should not exceed the

following:

a. d/4

b. 8 x diameter of the smallest

longitudinal bars.

c. 24 x diameter of hoop bars.

c. 300 mm

First hoop shall be located not more than

50mm from face of support.



3. Where hoops are not required, stirrups

with seismic hooks shall be spaced at a

distance not more than d/2 throughout the

length of the member.



hhoops

2h

50mm max50mm max 50mm max

Hoop spacing is smallest of:

d/4 ; 8db ; 24 hoop db ;

300mm ; STAAD Pro output

Spacing of stirrups d/2

hoops hoops

2h 2h

Special Detailing on Transverse Reinf.

Sample of design output from STAAD Pro

56J 5000 X 300 X 400 58J

4No20 H 342. | 0 TO 148414*10c/c 178

4No20 H 342. | 3308 TO 500014*10c/c178

5No12 H 54. | 802 TO 3989

5000

400

1484 1692

4-20mm 4-20mm

5-12mm 14 hoops of 10mm@ 178 o.c.14 hoops @10mm@ 178 o.c.

802 1102

Physical representation

54

342

Beam Detail With Seismic Provision

400

800mm S=90mm

2900S=178mm

From STAAD

50mm max 50mm max

4-20mm

5-12mm

b

4-20mm

2-12mm2-12mm

10mm hoops / stirrups

2-20 mm

800mmS=90mm

b5000

Hoop spacing is smallest of : d/4 ; 8db ; 24 hoop db ;

300mm and STAAD Pro

Beam Detail With Seismic Provision

5000

400

800mm S=90mm

2900S=178mm

From STAAD

50mm max 50mm max

4-20mm

2-20mm

Hoop spacing is smallest of : d/4 ; 8db ; 24 hoop db ;

300mm and STAAD Pro

b

4-20mm

2-20mm2-20mm

10mm hoops / stirrups

2-20 mm

800mmS=90mm

b

Bottom bars of 5-12mm < 2-20mm

5-12mm 2-12mm2-12mm

33. . COLUMNCOLUMN DESIGNDESIGN

Column design in STAAD per the ACI

code is performed for axial force,

uniaxial and biaxial moments.

The loading which produces the

largest amount of reinforcement is

called the critical load.

33. . COLUMNCOLUMN DESIGNDESIGN

Column design is done for square,

rectangular and circular sections.

For rectangular and circular

sections, reinforcement is always

assumed to be equally distributed on

all faces. This means that the total

number of bars will always be a

multiple of four (4).

Column design inside the STAAD program

1. The Bresler Load Contour method is

adopted by STAAD Pro for columns

under axial force, uniaxial and biaxial

moments.

2.The program will iterate a steel ratio from

1% to a maximum of 8% for a given

column dimension.

3.When the adequate steel ratio is arrived

at, the iteration terminates and adopt the

steel ratio and then a steel area is

computed.

Column design inside the STAAD program

4. Otherwise, if the section is

inadequate, the report prompts that

the size needs to be increased.

5. Seismic provision is absent in STAAD

Pro. Thus the output must be checked

and adjusted accordingly.

Nominal Pn, Mn curve

Factored Pu, Mu

(ACI Capacity)

A

x

i

a

l

c

a

p

a

c

i

t

y

(

k

N

)

Moment Capacity (kN-m)

SAFE ZONE

for(Pu, Mu) pair

3.1. COLUMN INTERACTION DIAGRAM3.1. COLUMN INTERACTION DIAGRAM

UNIT KN METER

START CONCRETE

DESIGN

CODE ACI

FYMAIN 414

MAXMAIN 25 ALL

DESIGN COLUMN 23 25

END CONCRETE DESIGN

3.2. 3.2. STAAD DESIGN BRIEF

FOR COLUMNS

The following output is generated without any TRACK

definition, thus using the default of TRACK 0.0

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

COLUMN NO. 1 DESIGN PER ACI 318-05 - AXIAL + BENDING

FY - 415.0 FC - 25.0 MPA, RECT SIZE - 275.0 X 300.0 MMS, TIED

AREA OF STEEL REQUIRED = 882.8 SQ. MM

BAR CONFIGURATION REINF PCT. LOAD LOCATION

PHI

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

8 - 12 MM 1.097 4 END 0.650

(PROVIDE EQUAL NUMBER OF BARS ON EACH FACE)

TIE BAR NUMBER 12 SPACING 192.00 MM

3.3. 3.3. STAAD DESIGN OUTPUT

FOR COLUMNS

33. . 44. SEISMIC REQUIREMENTS . SEISMIC REQUIREMENTS FOR FOR

COLUMNCOLUMN

1. Longitudinal Reinforcements

(NSCP2010 421.6.3.1)

The reinforcement ratio g shall not be

less than 0.01 and shall not exceed 0.06.

The STAAD allows up to a maximum of

8%. Therefore, should the design be

adequate with a steel ratio more than

6%, the section size shall be increased

in order to satisfy a steel ratio of less

than or equal to 6%.

Flexural Strength (NSCP2010 421.6.1)

The flexural strength of the column should satisfy

the following:

Mnc (6/5) Mnb

Where:

Mnc - the sum of nominal flexural strengths of

columns framing into the joint, evaluated

at the faces of the joint.

Mnb - the sum of nominal flexural strengths of

the beams framing into the joint,

evaluated at the faces of the joint.

Mncbot

Mnctop

MnbrightMnbleft

(Mnctop + Mncbot) (6/5) (Mnbtop + Mnbbot)

VXPRIFROXPQPRPHQWFDSDFLW\PXVWEHKLJKHUWKDQWKHVXPRIWKHEHDPPRPHQWFDSDFLW\

Flexural Strength (NSCP2010 421.6.1)

33. 4. SEISMIC REQUIREMENTS . 4. SEISMIC REQUIREMENTS FOR FOR

COLUMNCOLUMN

2. Limiting size of columns

(NSCP2010 421.6.1)

The shortest cross-sectional

dimension, measured on a straight

line passing through the geometric

centroid, shall not be less than

300mm. (Sec 421.6.1.1)

The ratio of the shortest cross-

sectional dimension to the

perpendicular dimension shall not be

less than 0.4. (Sec 421.5.1.2)


COLUMNCOLUMN

3. Transverse reinforcement spacing

(NSCP2010, 421.6.4.3)

1. of the minimum member dimension.

2. Six times the diameter of the longitudinal

bar, and

3. as defined by the given equation.

So = 100 + (350-hx)

3

where 100mm < So < 150mm

hx = spacing of additional cross ties

or overlapping hoops, which

need not exceed 350mm on

centers.


COLUMNCOLUMN


(NSCP2010, 421.6.4.3)

b

hx hx hx

hx

hx

h

b/4

s 100+ (350- hx)

3

where

100mm


COLUMNCOLUMN


(NSCP2010, 421.6.4.1)

The transverse reinforcements shall be provided

over a length, lo, from each joint face . The

length, lo, shall not be less than the largest of:

1.1. The depth of the member at the joint face or The depth of the member at the joint face or

where the flexural yielding is likely to occur.where the flexural yielding is likely to occur.

2.2. OneOne--sixth of the clear span of the membersixth of the clear span of the member

3.3. 450 mm450 mm..


COLUMNCOLUMN


(NSCP2010, 421.6.4.1)

Where transverse reinforcements are not required

throughout the full length of the column, the hoops

of the remainder of the column length shall be

spaced at the smaller of :

a) 6 times the diameter of the longitudinal bars.

b) 150mm

COLUMNS WITH SEISMIC DETAILING

S

S

Clear height, lu

Larger of b or h

1/6 lu

450mm

6 Ldb

150 mm.

b

hx hx hx

hx

hx

h

b/4

s 100+ (350- hx) where 100

OUTPUT FOR COLUMN DESIGN

COLUMN NO. 333 DESIGN PER ACI 318-05 - AXIAL + BENDING

FY - 413.7 FC - 27.6 MPA, SQRE SIZE - 500.0 X 500.0 MMS, TIED

AREA OF STEEL REQUIRED = 9850.0 SQ. MM

BAR CONFIGURATION REINF PCT. LOAD LOCATION PHI

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

8 - 40 MM 4.021 9 STA 0.70

(PROVIDE EQUAL NUMBER OF BARS ON EACH FACE)

TIE BAR NUMBER 12 SPACING 320.00 MM

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

coincides with NSCP2010

reinf. pct is with 1% to 6%, ok.

not adequate for seismic requirements:

S= (500)=125mm

S=6(40)=240mm

S=4+(14-8.5)/3=5.8=145mm

Adopt S=125mm at lo=18 from joint

Adopt S=150mm at remainder.

125

450

450

2850

650

3500

125

150 500

500

424

424

8-40mm

12mm hoops

COLUMN DETAIL WITH SEISMIC PROVISION

BEAM / GIRDER

BEAM / GIRDER

SECTION

SAMPLE EXERCISE

800mm S=90mm

50mm max

300

2-20mm

4-20mm

300

8-20mm

400

300

STAAD Hoops without

seismic detailing:

16Lb = 16 (20) = 120

48Tb = 48 (10) = 480

Dcol = 300

Beam moment capacities:

Mnneg = 116 kN-m

Mnpos = 61 kN-m

(6/5) x (Mn++Mn-)= 212.4 kN-m

Column moment capacities:

Mnctop=Mncbot = 63 kN-m

Mnctop + Mncbot = 126 kN-m

Column is inadequate for seismic requirements.

Therefore, increase capacity of column

Mnctop

Mncbot

Mnneg

Mnpos

INCREASE COLUMN FLEXURE CAPACITY

COLUMN STRENGTH REQUIREMENT

(6/5) x (Mn++Mn-)= 212.4 kN-m

300MM X 300MM WITH 8-20MM BARS :

Mnctop +Mncbot = 126 kN-m, not ok


Mnctop +Mncbot = 162 kN-m, not ok


Mnctop +Mncbot = 219 kN-m >212.4 , thus ok

MAX STIRRUPS SPACING

a) 6 (20) = 120 mm

b) 150mm

smax = 120mm

STIRRUPS SPACING from the joints

at length lo = greater of

a) 375mm

b) 450mm

c) 1/6 of lu =1/6 (2850)=475mm

so that, lo = 450mm

1) s= b/4 = 375/4 = 94mm

2) s = 100+(350-0)/3 = 217 ,

100

REQUIRED STIRRUP SIZE

Where:

S spacing of stirrups

hc column core dimension measured from

center-to-center of confinng stirrups

Ag gross area of section

Ach area of column core

fc` - compressive strength of concrete

fyt yield strength of stirrups

Ash total area of number of legs in one

direction

s = 94mm fc` = 21 Mpa fyt = 275 Mpa

hc = 375 2 (32) = 311mm

Ag = (375)(375) = 140,625 sq.mm.

Ach = (311)(311) = 96,721 sq.mm.

REQUIRED STIRRUP SIZE

Using 10mm stirrups with 4 legs in one direction:

At = 4(78.54) = 314.16 sq.mm.

Ok since greater than 304.004 sq.mm

800mm

S=90mm

50mm max

400

300

Lo = 450

Lo = 450

4-20mm

2-20mm

smax= 120mm of 10mm hoops

sr= 94mm of 10mm hoops

375

375

12-20mm

3 sets of 10mm hoops

CONCLUSION

1.STAAD Pro output does not, as of yet,

have provisions for seismic detailing

requirement. All the generated design

results are based on maximum

stresses only.

Therefore, the output should not be

used as the final detail without

modification when designing for SMRF.

2. The seismic detailing should start first

on the beam: supports and midspan

requirements must be satisfied before

going to the columns.

Modify the beam STAAD output to suit

the seismic requirements.

CONCLUSION

3.The columns connected at a joint should

be 20% (or 6/5) stronger than the beams

connected at that same joint in terms of

flexure.

Since the beam is already fixed, the

column STAAD results must be adjusted

to fit the seismic requirements at that

joint.

CONCLUSION

4. Finally, once the seismic requirements

are satisfied, then and only then the

detailed drawings are carried out.

CONCLUSION

THANK YOUTHANK YOU

staad training - module 3 - malaybalay city june 2011_2

Documents

staad design output

staad design brief

reinforced concrete

concrete design calculation

series of iteration

stad design output

design of steel reinforcements

working stress design