technical - mabey data sheet superprop document ref: tdssprop page no. 3 of 23 the information on...

T E C H N I C A L D A T A S H E E T

Superprop

Document Ref: TDSSPROP Page No. 1 of 23 THE INFORMATION ON THIS DATA SHEET REMAINS THE PROPERTY OF MABEY HIRE

LTD. AND IS NOT TO BE REPRODUCED WITHOUT WRITTEN PERMISSION. WE RESERVE THE RIGHT TO AMEND THIS DATA AT ANY TIME WITHOUT PRIOR

NOTICE AND YOU SHOULD THEREFORE CHECK OUR WEBSITE TO ESTABLISH ITS VALIDITY .

Issue No: 05 Further Information Tel: +44 (0) 1942 725 343

Issue Date: MAY 16

www. mabeyh i r e . co .uk ac t i on@mabeyh i r e . co . uk

Technical Data Sheet

Mabey Hire Ltd. Structural Support & Bridging Bridge House, Strange Road, Garswood, Lancashire WN4 0RX United Kingdom Telephone: +44 (0) 1942 725 343 Facsimile: +44 (0) 1942 270 893 Email: [email protected] Website: www.mabeyhire.co.uk

Mass 25 Mass 50 MAT 125

Superprop Hydraulics

Quickbridge MU Falsework

MU Bridging Compact Bridging BarrierGuard 800

Instrumentation


Superprop





Issue Date: MAY 16


Index

Reference Description Page No.

Title Page 1 Contents 2

1.0 Introduction 3 2.0 Section Properties and Weights

2.1 Props & Prop Extensions 4 2.2 Adjustable Ends 5 2.3 Bracing 6 2.4 Beams 7

3.0 Capacities 3.1 General 8 3.2 Adjustable Ends - Capacities 8 3.3 Free Standing Props - Capacities 11 3.4 Braced Props 12 3.5 Beams - Capacities 17 4.0 Special Applications 4.1 Raking Prop 18 4.2 Superprop Towers 19 5.0 Equipment List 20 6.0 Bolt Application Table 21 7.0 Assembly Details 22 8.0 Design Procedure 23

Contents


Superprop





Issue Date: MAY 16


Application

This Technical Data Sheet is designed to provide information of sufficient content and detail as to enable engineers, competent in structural analysis & structural steelwork design to safely design structures incorporating the Superprop system.

Design Codes

Superprop is primarily used for temporary heavy jacking and shoring applications, where its strength and adaptability make it suitable for most schemes. As such it has been designed to the following codes.

BS5975: 2008 – The Code of Practice for Temporary Works Procedures and the Permissible Stress Design of Falsework

BS449: 1969 - The Structural Use of Steel in Building (as referenced in BS5975)

Eurocodes

The equipment is currently being assessed to Eurocodes. Strengths relating to these codes will be published in a future revision to this document. Please refer to Mabey Hire engineering team for the latest information.

Safe Working Loads

The safe working loads for members & joints given in the Technical Data Sheet are generally based on theoretical values calculated in accordance with BS5975 & BS449 as well as the component capacities that have been derived from full scale tests. Where full scale tests have been carried out a minimum factor of safety of 1.7 against the onset of permanent deformation has been established.

1.0 Introduction


Superprop





Issue Date: MAY 16


2.1 Props & Prop Extensions

2.1.1 Details

The Prop units are formed from four pairs of back to back 102x51x10kg/m RSC sections. These are braced by a prop chord connector at a maximum of 1524mm centres. Prop units can be joined end to end using 4 No. Pins to any desired length.

2.1.1.1 Fittings

Part No. Length (mm)

Weight (Kg)

SPA002 3048 462.0

SPA003 1524 277.0

SPA004 762 187.0

SP031 1000 260.0

SP030 385 197.3

SP049 50 76.0

2.0 Section Properties & Weights

Note: SP031, SP030, SP049, SP001 and SP012 all have 8No, 26mm dia holes in each baseplate.

SP081 or SP080 along with an M30 x 180mm bolt are used to connect parallel Prop units together through the 4No. connections along the SuperProp shaft. As an alternative a SP070 and SP071 can be used as a replacement.

BB04 along with BB04A are used to connect Prop units together end to end through the 4No. connections at each end of the Prop body.

Note: Only where there are no horizontal loads on the prop system may the Shear Pin Connector SP081 be used.

Note: When using a SP081 or a SP080 / SP070 to connect Props together you MUST consider that the props will be acting as freestanding props with no extra capacity due to the bracing effect.

BB04

Panel Pin

211mm

O/All

BB04A

Safety 'R' Clip


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Issue Date: MAY 16


2.1.2 Section Properties

2.2 Adjustable Ends

2.2.1 Details

NB: In tension an additional Adjustment Nut (SP005) is required which reduces the stroke by 50mm.

Area (cm2) Inertia (cm

4) Section Modulus (cm

3) Radius of Gyration (cm)

A Ixx Iyy Zxx Zyy rxx ryy

Props 106.2 23690 23690 940 940 14.9 14.9

Prop Extensions 135.0 19850 19850 1117 1117 12.1 12.1

Part No.

Adjustment Range (mm)

Weight (kg)

Male Adj. End SPA001 779 – 1194 346.0

Female Adj. End SPA007 779 - 1194 367.0



Superprop





Issue Date: MAY 16


2.3 Bracing

2.3.1 Details

Superprop is braced using a special bracing panel that bolts into the chord blocks using chord bolts. The panels are a standard 1549mm wide (Prop centres 2050mm) available in heights of 1524mm and 3048mm.

`

2.3.1.1 Fittings


Weight (Kg)

AB001 3048 267.0

AB016 1524 160.0


BB04

Panel Pin

211mm

O/All

BB04A

Safety 'R' Clip

Alternative type bolts to connect Bracing Panels to Bracing Panels and Bracing Panels to Superprop shafts. Note: A SP073 Washer MUST be called off with every AB057

and SP077 bolt.

BB04 along with BB04A are used to connect Bracing Panels together end to end through the 2No. connections at each end of the Bracing Panel.


Superprop





Issue Date: MAY 16


2.4 Beams

2.4.1 Details

The Superprop header beams are formed from paired 406x178x67Kg/m UB sections and joined with diaphragms at 250mm web centres. The twin header beams are available in lengths of 2m, 4m and 6m. Each beam is fitted with male and female end connections within the web depth, leaving the flange clear whilst providing significant moment capacity. Mabey Hire also maintain a stock of various other beams should you have any special requirements. 2.4.1.1 Fittings

2.4.2 Section Properties


Weight (Kg)

SPA012 2000 517.8

SPA008 4000 800.0

SPA009 6000 1163.6

Area (cm2) Inertia (cm

4) Section Modulus (cm

3) Radius of Gyration (cm)

A Ixx Iyy Zxx Zyy rxx ryy

Single Beam 85.5 24329 1365 1188 153 16.9 4.0

Twin Beam 171.0 48660 29448 2376 1373 16.9 13.1


Using an SP018 with M24 Gr 8.8 bolt or thread bar the capacity of the fitting is 118 kN (which is the maximum capacity of the M24 bolt / thread bar).

6No. AB051’s along with 12No. AB052’s are used to connect beams together end to end through the connections at each end of the beam.


Superprop





Issue Date: MAY 16


3.1 General The safe working load of the prop is dependent on:-

a) Vertical load b) Eccentricity of the load c) Extension of the adjustable screw d) Horizontal loading e) Free standing height f) Effective length of the prop between bracing levels g) Self-weight effects if horizontal or raking

3.2 Adjustable Ends - Capacities 3.2.1 Effective lengths of Adjustable Ends

The Effective Length of the Adjustable Screw in various loading cases is demonstrated in the diagrams below. For purposes of design it has been assumed that the screw assembly is pinned at both the point of application of the horizontal load (indicated by ‘H’) and at the top of the screw collar. Thus, in accordance with BS5975 and BS449 the effective length of the screw assembly (Le) equals the actual distance (L) between these assumed pin positions. The lengths should therefore be applied when using the graphs Charts A and B. Note that in the graphs the horizontal load (H) is given as a percentage of the vertical load in the prop (V):-

Note:

In all three cases shown here it is assumed that the Header Beams are clamped to the Prop using the Beam Clamp (SP018)

3.0 Capacities

(A) (B)

(C) Jack with spherical head

Connecting member to other prop

Le

H

Le

H

Le

H


Superprop





Issue Date: MAY 16


3.2.2 Adjustable Ends – Working Load Capacities

Props in Tension:

Superprop screws are primarily used in compression but may be used in tension with the addition of an optional nut (SP005) fitted on the screw below the 50mm plate on the SPA001 Adjustable Head Assembly. The tension capacity of the screw is limited by the connecting pin between the SP003 screw and the SP011 screw head plate or the connection of the Screw Head Plate to the Header Beams or the structure. The Maximum Tension Capacity of the SPA001 Screw Head Assembly fitted with the optional tension nut is 650kN

Props in Compression:

The capacities of the Adjustable Head Assembly are shown in the charts below for varying effective lengths and for eccentricities of 10mm or 25mm:

3.0 Capacities

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600

All

ow

ab

le A

xia

l L

oa

d (

kN

)

Effective Length Le (mm)

Adjustable Head/Base Unit, e=10mm

H=0%V

H=1%V

H=2.5%V

H=5%V

Designers should be aware of ensuring that eccentricities of loads on the system are kept to a minimum, within these tables. The capacity of the propping system will be greatly reduced if, for example, when using twin header beams the load is diverted down only one of the webs of the beams in which case an appropriate eccentricity should be calculated.

500

700

900

1100

1300

1500

1700

1900

2100

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

S.W

.L. (k

N)

Le (m)

Chart A - Adjustable Head/Base Unit, e = 10mm (Working Loads to BS5975)

H = 0%V

H = 1%V

H = 2.5%V

H = 5%V

Le

Heccentricity e

V


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Issue Date: MAY 16


3.0 Capacities

500

700

900

1100

1300

1500

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

S.W

.L. (k

N)

Le (m)

Chart B - Adjustable Head/Base Unit, e = 25mm (Working Loads to BS5975)

H = 0%V

H = 1%V

H = 2.5%V

H = 5%V


Superprop





Issue Date: MAY 16


3.3 Free Standing Props – Capacities

Free standing props may be used in backpropping where no horizontal forces are present. Chart C below gives the safe working loads for varying effective lengths of props with applied loads at eccentricities of 10 and 25mm, and an adjustable screw at each end. It should be noted that the effective length of the prop is assumed to be the distance between the pins connecting the head and sole plates to the prop body. 3.3.1 Prop Extension Capacity (to BS5975)

SP030- 385mm

Extension SP031 – 1000mm

Extension

Axial Compression (No Eccentricity) (kN) 2400 2400

Axial Tension (No Eccentricity) (kN) 396 396

End Plate Moment Capacity (4 bolts) (kNm) 61.4 61.4

End Plate Shear Capacity with maximum moment (4 bolts) (kN) 170 170

End Plate Shear Capacity without moment (4 bolts) (kN) 340 340

3.0 Capacities

Note: The above capacities assume the extensions are connected using 4No M24 grade 8.8 bolts

1000

1200

1400

1600

1800

2000

2200

2 3 4 5 6 7 8 9 10 11 12

S.W

.L. (k

N)

Effective Length of Prop = Le (m)

Chart C - Axial Capacity (Working Loads to BS5975)

e = 10mm

e = 25mm

Max. allowable load on adjustment screw 25mm eccentricity

Max. allowable load on adjustment screw 10mm eccentricity

Note: Overall Prop capacity may be limited be screw jack – see 3.2.2.


Superprop





Issue Date: MAY 16


3.4 Braced Props

Superprops may be assembled and braced in various ways in order to produce the required pattern of supports. The effective lengths of normal arrangements are shown in the diagrams below. These effective lengths may be used to determine the load carrying capacity of the individual props by reference to the charts for braced props (see Charts E and F). Also there is a maximum effective length that must not be exceeded under a particular horizontal load before the bracing frame (3048mm panel or 1425mm panel) connection to the prop body becomes overloaded (see Chart D). Use the following diagrams to assist in calculating the effective lengths of the various sections of the prop assembly:

The diagrams of bracing arrangements shown show the effective lengths at the base with a prop base fitted (SP 005), but do not include the effective lengths of the adjustable ends, for these values reference should be made to the above diagram and the guidance in section 3.2.

3.0 Capacities

The type of base extension will have an effect on the effective length of this section of prop as indicated here by the use of the SP030 or SP031.

Le =

191

3

Le =

129

843

979

9 Le o

f Adj

usta

ble

Hea

d

see

guid

ance

on

page

8

SP031

SP030

Var

ies

Le =

913

Le =

243

7

Le =

876

Le =

876

1524

3048

1524

3048


Superprop





Issue Date: MAY 16


3.0 Capacities

Le =

396

1

Le =

913

Le =

876

2 x

Le =

232

3

Le =

116

2

Le =

913

2 x

Le =

235

9

Le =

118

0

1524

762

3048

3048

3048

3048

762

3048

Le =

913

2 x

Le =

312

1

Le =

156

1

Le =

913

2 x

Le =

464

5

Le =

232

3

Le =

913

3048

1524

3048

3048

3048

3048


Superprop





Issue Date: MAY 16


3.0 Capacities

Le =

913

Le =

876

Le =

243

7

Le =

913

Le =

876

Le =

396

1

2 x

Le =

232

3

Le =

116

2


Superprop





Issue Date: MAY 16


3.4.1 Safe Working Load Charts for Braced Props

3.0 Capacities

Le =

913

Le =

913

Le =

913

2 x

Le =

312

1

Le =

156

1

2 x

Le =

464

5

Le =

232

3

Le =

913

2 x

Le =

235

9

Le =

118

0

0

10

20

30

40

50

60

70

80

1 2 3 4 5 6 7 8 9 10 11 12

Ho

rizo

nta

l L

oa

d (

kN

)

Effective Length (m)

Chart D - Maximum Horizontal Load/Effective Lengths to ensure Bracing Panel Connection not Overloaded using AB57 Chord Bolts

AB1/AB57 Combination

AB16/AB57 Combination


Superprop





Issue Date: MAY 16


3.0 Capacities

0

500

1000

1500

2000

2500

1 2 3 4 5 6 7 8 9 10 11 12

S.W

.L. (k

N)

Effective length of prop Le (m)

Chart E - Braced Prop Capacity : (Working Loads to BS5975) 10mm Eccentricity

H = 0%V

H = 1%V

H = 2.5%V

H = 5%V

0

500

1000

1500

2000

1 2 3 4 5 6 7 8 9 10 11 12

S.W

.L. (k

N)

Effective length of prop Le (m)

Chart F - Braced Prop Capacity: (Working Loads to BS5975) 25mm Eccentricity

H = 0%V

H = 1%V

H = 2.5%V

H = 5%V

Note: Graphs DO NOT include the Adjustable Head/Base Unit. These are to be checked separately to the Props, refer to Charts A and B.


Superprop





Issue Date: MAY 16


3.5 Header Beams - Capacities 3.5.1 Load Capacities

Notes: • Capacities given are for the major X-X axis.

• Checks may be required if the beams are subject to combined bending and shear. • Reaction (Buckling and Bearing) values are based on a 400mm stiff bearing length. • The beam bending values are based on a maximum bending stress on an effective length of beam

of up to 2050mm. • Top and bottom flanges assumed to be prevented from translation relative to each other.

Single Beam Twin Beam

(SP015,SP016,SP020) (SPA008,SPA009,SPA012)

Beam Shear Capacity (kN) 440 880

Max Beam Bending Resistance (kNm) 273 546

Maximum Reaction (kN) 955 1910

Splice Shear Capacity (kN) 328 656

Splice Bending Resistance (kNm) 182 364

3.0 Capacities

y

y

x x


Superprop





Issue Date: MAY 16


4.1 Raking Prop

With the standard Swivel Head (SPA001) and Base unit (SPA007) the Superprop can easily be adapted to raking applications. Design Considerations:

a) The standard adjustable prop head (SPA001) is only able to accept tilts of up to 10 degrees; if the angle between the

prop and the waler is greater than 10 degrees then a special swivel head would be required. As the connection of this special swivel head plate and the screw is only through the connecting pin then the capacity of the prop in compression would be limited to 650kN.

b) For inclined props it will be necessary to check the axial capacity of the prop taking into consideration the eccentricity of the axial load due to self-weight bending of the prop itself PLUS an allowance for pin hole tolerance deflection (see below).

c) In order to limit the self-weight and pin hole tolerance deflection of the prop it is possible to add bracing panels or bracing chords to one side of the prop.

d) Preloading of the prop from within the adjustable head is only possible if the SP011 screw head plate is fitted and it is orientated at 90 degrees to the axis of the prop.

Pin Hole Tolerance Deflection:

Pin hole tolerance will depend on the number of sections of props that are pinned together and the angle of the prop to the vertical. Unless the prop is near vertical it is safe to assume that this deflection will occur at the maximum value. The figures in the table above give an indication of the magnitude of the deflection that should be considered when calculating the raking prop safe working load.

Maximum Deflection for a Single Raking Prop

due to Pin Hole Tolerance

No of 3048mm Modules)

Sag (mm)

2 6.05

3 13.61

4 24.20

5 37.81

Special shear connectors may be required to connect the top of the prop with the soldiers or walings.

4.0 Special Applications

Note: Preloading of the raking prop can only occur when the head plate of the Adjustable Unit is a right angle to the prop axis.

Thrust Block of concrete or similar, designed with adequate horizontal shear capacity.

Restraint required between concrete and

wall to prevent uplift.


Superprop





Issue Date: MAY 16


4.2 Superprop Towers

The prop chord connector is fitted with four 26mm diameter holes in the top and bottom plates. These holes may be used to fit proprietary push pull props or special bracing that may be used to plan brace the Superprop tower.

Elevation

AB001 Bracing Panels

Superprops

4.0 Special Applications

Plan


Superprop





Issue Date: MAY 16


NB: Stock levels of certain parts listed above are limited – please check availability with our engineers.

Part No. Description Weight

(kg) Part No. Description

Weight (Kg)

SPA001 ADJUSTABLE HEAD ASSY 346.0 SP032 762mm PROP EXTENSION 298.9

SPA002 3048mm MODULE 462.0 SP034 CANT WALKWAY BRACKET 9.5

SPA003 1524mm MODULE 277.0 SP036 CANT WALKWAY CORNER 9.0

SPA004 762mm EXTENSION 187.0 SP039 P/P ADAPTOR (PROP) 7.3

SPA005 BASE UNIT 108.0

SPA006 385mm EXTENSION 198.0 SP040 75mm JACKING PACK 5.8

SPA007 ADJUSTABLE BASE ASSY 367.0 SP041 UNIVERSAL P/P ADAPTOR 11.0

SPA008 TWIN HEADER BEAM 4m 800.0 SP049 50mm SPREADER PLATE 76.0

SPA009 TWIN HEADER BEAM 6m 1163.6

SPA010 3048mm HEAD MODULE 810.0 SP070 SUPER PROP SPACER PLT 5.8

SPA011 MOD SP009 C/W 2NO SP041 177.0 SP071 TWIN CHORD BOLT 0.1

SPA012 TWIN HEADER BEAM 2m 517.8 SP073 1.1/4 BSW WASHER 0.05

SP076 TWIN S/PROP BASE/HEADER BEAM 298.0

SP001 PROP FLAT BASE FEMALE 95.3 SP077 TWIN S/PROP CHORD BOLTS 0.3

SP002 SCREW SOLE PLATE 100.0 SP078 300mm JACKING PACK 13.4

SP003 ADJUSTMENT SCREWS 98.4 SP079 250mm JACKING PACK 12.0

SP004 ADJUSTMENT NUTS 7.0

SP005 ADJUSTMENT TENSION NUTS 4.5 SP080 SUPERPROP SPACER BLOCK 4.2

SP006 PROP BASE FEMALE 145.0 SP081 SUPERPROP SHEAR PIN CONNECTOR 5.0

SP007 PROP CHORD CONNECTOR 34.9 SP082 1m SUPERPROP HEADER BEAM 271.0

SP008 BOLT/HSFG WASHERS 0.1 SP083 TRANSFER PLATE 31.0

SP009 762mm PROP EXTENSION 187.0

AB001 3048mm ACROW PANEL 267.0

SP010 PROP HEAD (MALE) 141.1 AB010 3048mm REINFORCING CHORD 92.0

SP011 SCREW HEAD PLATE 95.3 AB016 1524mm ACROW PANEL 160.0

SP012 PROP FLAT PLATE 104.8 AB021 1524mm REINFORCING CHORD 57.0

SP015 4m HEADER BEAM 370.0 AB051 ACROW PANEL PIN 2.7

SP016 6m HEADER BEAM 540.0 AB052 ACROW PIN CIRCLIP 0.1

SP017 HEADER BEAM DIAPHRAGM 19.1 AB057 CHORD BOLT 1.1/4 1.3

SP018 HEADER BEAM CLAMP PLT 2.0 AB079 HEAVY PIN & CLIPS 4.0

SP019 BEAM CLAMP PLATE MKIT 1.0 AB803 ACROW PANEL 700 (HYBRID) 322.5

AB804 ACROW PANEL 700 (HIGH SHEAR) 388.5

SP020 HEADER BEAM 2m 370.0

SP026 150mm JACKING PACK 11.2 BB004 PANEL PIN 2.7

SP027 50mm JACKING PACK 1.0 BB004A SAFETY ‘R’ CLIP 0.1

SP029 TOP NUT ‘C’ SPANNER 0.5 SPROLL SUPERPROP BEAM ROLLER 25.0

SP030 385mm PROP EXTENSION 197.3 SPSKAT SUPERPROP SKATE ASSEMBLY 97.0

SP031 1000mm PROP EXTENSION 260.0

5.0 Equipment List


Superprop





Issue Date: MAY 16


Connection Type Bolt Details Qty.

Prop Module to Prop Module Panel Pin (BB04) & Safety ‘R’ Clip (BB04A) 4

Prop Module to Prop Flat Base/Head Panel Pin (BB04) & Safety ‘R’ Clip (BB04A) 4

Prop Module to Adjustable Head Assembly Panel Pin (BB04) & Safety ‘R’ Clip (BB04A) 4

Prop Module to Adjustable Base Assembly Panel Pin (BB04) & Safety ‘R’ Clip (BB04A) 4

Header Beam End to Header Beam End Panel Pin (AB051) & 2No. Pin Circlips (AB052) 6

Header Beam Clamp to Prop Screw Head M24 x 125mm 1

Header Beam Clamp to Flat Prop Base/Head M24 x 125mm 1

Prop Extension to Prop Flat Base M24 x 125mm 4

1m Header Beam to Prop Screw Head M24 x 110mm 2

1m Header Beam to Flat Prop Base/Head M24 x 110mm 2

Header Beam Web to Push Pull Adapter M24 x 80mm 2

Jacking Pack to Prop Flat Base/Head M24 x 80mm 2

Jacking Pack to Jacking Pack M24 x 60mm 2

Cantilever Walk Way to Prop Module M24 x 80mm 1

Prop Chords to Push Pull Adapter Chord Bolt (AB057 or SP077) & Washer (SP073) 1

Prop Chords to 1524mm Bracing Panel Chord Bolt (AB057 or SP077) & Washer (SP073) 4

Prop Chords to 3048mm Bracing Panel Chord Bolt (AB057 or SP077) & Washer (SP073) 8

Prop Chords to Prop Chords Various (see section 7.0 and Additional Note)

1524mm Bracing Panel to 1524mm Bracing Panel Chord Bolt (AB057 or SP077) & Washer (SP073) 2

3048mm Bracing Panel to 3048mm Bracing Panel Chord Bolt (AB057 or SP077) & Washer (SP073) 4

6.0 Bolt Application Table


Superprop





Issue Date: MAY 16


NB: All bolts and connections MUST be fitted as shown above.

7.0 Assembly Details

Note: When using a SP081 or a SP080 / SP070 to connect parallel Props together you MUST consider that the props

will be acting as freestanding props with no extra capacity due to the bracing effect. Only where there are no horizontal loads on the prop system may the Shear Pin Connector SP081 be used.


Superprop





Issue Date: MAY 16


Design Assumptions:

The tables and charts within these data sheets use working stress design and unfactored loads or are based on tested

components. The use of BS5975 (Code of Practice for Falsework) is relevant which, in turn, uses the working stress principles

of BS449 (The Use of Structural Steelwork in Buildings).

Propping Layout:

1. Using the scheme information decide on the rough layout of the propping system. When supporting a concrete bridge

deck it is usually possible to decide on the location of the props but not the spacing whereas when supporting steel or

concrete beams the layout of props may be more prescriptive.

2. Using the clients data calculate the dead and live loads on the prop system, taking care with pattern loading from

traffic loads (if present) on continuous spans.

3. Arrange prop spacing as necessary to optimise the loading in the props using standard bracing. Ideally the prop loads

should be similar to assist jacking.

4. Ensure that the prop screw head plate pivot pins are orientated perpendicular to the line of the header beams.

Header Beams:

1. Check the loading to the header beams and calculate the bending moments and shears at the full section and splices

in the beams. Compare the moments and shears with the data in capacity tables in section 3.

2. If the header beams are overstressed then reduce the prop spacing and recalculate.

Prop Screw:

1. Check the screw effective lengths. The effective length depends on the orientation of the head plate pivot pin, the

actual or assumed eccentricity of the load, the expected or assumed horizontal loading at the top of the screw and the

distance to the assumed pin joint at the top of the screw (see section 3.2).

2. It is usual to apply a nominal eccentricity to the vertical load of either 10mm or 25mm which will depend on the

arrangement of the equipment above the prop. If clamped header beams are used then 10mm eccentricity would be

usual but with loose jacks or packs, then a 25mm eccentricity may be more appropriate.

3. The horizontal loading on the props should be limited to a nominal value, usually 2.5%. Any large external horizontal

loads such as skidding loads on the deck should be taken down to the ground using a separate raking member. In

which case the nominal horizontal load may be reduced to 1%.

4. Using charts A or B in section 3.2 of these sheets check the allowable maximum extension.

5. If the actual screw extension is greater than the allowable then the prop make up should be amended in order to

reduce the screw extension.

Braced Structure:

1. Bracing frames may be either Acrow 300 series panels or special bracing frames. All these bracing panels attach to

the prop bodies at chord bolt positions, each AB001 panel using 4 chord bolts on each side. It is the capacity of these

chord bolt connections that are the limiting feature of the bracing system.

2. The effective lengths of the props are measured from the centres of a pair of chord bolts to various locations on the

props. Various arrangements of Acrow Panels used as bracing frames are shown in these data sheets on section 3.4.

Using these diagrams note the effective lengths at various positions on the prop.

3. The effective length at the adjustable head must be calculated separately (see section 3.4).

4. Using the maximum effective length calculated from either the adjustable head or prop body, the safe working load of

the prop may be checked from the charts on section 3.4.1 for various eccentricities and horizontal loads.

5. If the capacity of the prop is not sufficient then a reduction in the effective lengths should be carried out, either by

adding bracing panels or reducing the screw extension.

8.0 Design Procedure

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