Technical Data Sheet. Eurocode Compliant. T E C H N I C A L D A T A S H E E T Superprop. Mass 25 Mass 50 MAT 125 Superprop

Transcription

1 Technical Data Sheet Eurocode Compliant Mass 25 Mass 50 MAT 125 Hydraulics Quickbridge MU Falsework MU Bridging Compact Bridging BarrierGuard 800 Instrumentation Mabey Hire Ltd. Structural Support & Bridging Bridge House, Strange Road, Garswood, Lancashire WN4 0RX United Kingdom Telephone: +44 (0) Facsimile: +44 (0) Website: Document Ref: EC-TDSSPROP Page No. 1 of 27

2 Contents Index Reference Description Page No. Title Page 1 Contents Introduction, Use of the Data Section Properties and Weights 2.1 Props & Prop Extensions Adjustable Ends Bracing Beams General Adjustable Ends - Capacities Free Standing Props - Capacities Braced Props Beams - Capacities Special Applications 4.1 Raking Prop Towers Equipment List Bolt Application Table Assembly Details Design Procedure 27 Document Ref: EC-TDSSPROP Page No. 2 of 27

3 1.0 Introduction 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 system. Design Standards The resistance values given in this data sheet have been calculated in accordance with the following Eurocode Standards: BS EN :2005 incl. corrigenda Feb 2006 and April 2009 BS EN :2006 incl. corrigendum Nov 2009 BS EN :2006 incl. corrigendum April 2009 BS EN :2005 incl. corrigenda Dec 2005, Sept 2006, July 2009 and Aug 2010 Design Philosophy The British Standard method of permissible stress design has been replaced by the Eurocode limit state design method, which utilises a partial factor method. The principles of the Eurocode design method are outlined below. The design value of an action effect shall not exceed the corresponding design resistance of the element: F d R d Where: F d = Ɣ F x F k R d = R k / Ɣ M d The design value of an action effect shall not exceed the corresponding design resistance of the element: Where: F d = Ɣ F x F k Rd = R k / Ɣ M F d is the design value of an action (be that a force, moment, or shear etc.) R d is the design value of the resistance (be that a force, moment, or shear etc.) F k is the characteristic value of an action (such as dead load, live load etc.) Ɣ F is the partial factor for actions R k is the characteristic value of the resistance (e.g. axial capacity) Ɣ M is the partial factor for a material property This data sheet gives Safe Working Capacities by assuming a Ɣ F value of Ɣ M is used in accordance with the Eurocodes. Please refer to further details on the following page. Document Ref: EC-TDSSPROP Page No. 3 of 27

4 1.0 Introduction How this Eurocode Data has been Established This data sheet gives Safe Working Capacities that may be compared to actual loads/effects. Mabey Hire has chosen not to publish Design Resistance values because they could lead to errors and unsafe designs due to:- Values being mistaken for SWL values (major risk) The risk of low Partial Factors being used in certain circumstances resulting in overall Factor of Safety (FOS) values of < 1.40, inappropriate for Temporary Works The Characteristic Resistances of all the products have been assessed in detail in accordance with the Eurocodes. Where the values have been influenced by the results of testing, the use of the test data has also been carried out in accordance with the requirements of the Eurocodes. Diagram Illustrating Factors R k Ɣ M x (Ɣ F = 1.50) Mabey Strength Safe working capacities in this data sheet are the lesser of these two values Min FoS = 2.0 How to Use the Technical Data Sheet a) Use SWL values straight from the data sheet. In cases where the Eurocodes specify Ɣ F > 1.50 (e.g. certain rail and wind actions) then method (b) below should be adopted. Or b) Providing that Actions (Loads) have been multiplied by Ɣ F (Load Factors) to produce Design Load Effects, then tabulated values may be multiplied by 1.50 to give minimum Design Resistances and compared to the Design Load Effect. Minimum FOS When using method (b), Mabey Hire imposes a minimum Ɣ F x Ɣ M of This is to eliminate lower FOS values that would be inappropriate for Temporary Works. We recommend that you contact Mabey Hire engineers for guidance. Document Ref: EC-TDSSPROP Page No. 4 of 27

5 2.0 Section Properties & Weights 2.1 Props & Prop Extensions 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. Note: SP031, SP030, SP049, SP001 and SP012 all have 8No, 26mm dia holes in each baseplate Fittings 211mm O/All BB04 Panel Pin BB04A Safety 'R' Clip 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. Part No. Length (mm) Weight (Kg) SPA SPA SPA SP SP SP Note: Only where there are no horizontal loads on the prop system may the Shear Pin Connector SP081 be used. 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. 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. Document Ref: EC-TDSSPROP Page No. 5 of 27

6 2.0 Section Properties & Weights Section Properties Area (cm 2 ) Inertia (cm 4 ) Section Modulus (cm 3 ) Radius of Gyration (cm) A I y I z W el,y W el,z i y i z Props Prop Extensions Adjustable Ends Details Part No. Adjustment Range (mm) Weight (kg) Male Adj. End SPA Female Adj. End SPA NB: In tension an additional Adjustment Nut (SP005) is required which reduces the stroke by 50mm. Document Ref: EC-TDSSPROP Page No. 6 of 27

7 2.0 Section Properties & Weights 2.3 Bracing Details 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. Part No. Length (mm) Weight (Kg) AB AB Fittings 211mm O/All BB04 Panel Pin BB04A Safety 'R' Clip 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. Alternative type bolts to connect Bracing Panels to Bracing Panels and Bracing Panels to shafts. Note: A SP073 Washer MUST be called off with every AB057 and SP077 bolt. Document Ref: EC-TDSSPROP Page No. 7 of 27

8 2.0 Section Properties & Weights 2.4 Beams Details The 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. Part No. Length (mm) Weight (Kg) SPA SPA SPA Fittings 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 Section Properties Area (cm 2 ) Inertia (cm 4 ) Section Modulus (cm 3 ) Radius of Gyration (cm) A I y I z W el,y W el,z i y i z Single Beam Twin Beam Document Ref: EC-TDSSPROP Page No. 8 of 27

9 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 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 the Eurocode 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):- (A) H (B) Connecting member to other prop H Le Le (C) Jack with spherical head H Note: In all three cases shown here it is assumed that the Header Beams are clamped to the Prop using the Beam Clamp (SP018) Le Document Ref: EC-TDSSPROP Page No. 9 of 27

10 3.2.2 Adjustable Ends Safe Working Load Capacities Props in Tension: 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 Safe Working Tension Capacity of the SPA001 Screw Head Assembly fitted with the optional tension nut is 650kN (based on testing) Props in Compression: eccentricity e V H Le 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. The capacities of the Adjustable Head Assembly are shown in the charts below for varying effective lengths and for eccentricities of 10mm or 25mm: Note: Safe Working Loads assume F = 1.5 and M = 1.1, ie combined factor = 1.65 Document Ref: EC-TDSSPROP Page No. 10 of 27

11 S.W.L. (kn) S.W.L. (kn) T E C H N I C A L D A T A S H E E T Chart A Safe Working Loads for Adjustable Head/Base Unit, e = 10mm ( F X M = 1.65) 2500 Screw Capacity - 10mm Load Eccentricity % 1% 2.50% 5% Effective Length of Screw (mm) Chart B Safe Working Loads for Adjustable Head/Base Unit, e = 25mm ( F X M = 1.65) 1800 Screw Capacity - 25mm Load Eccentricity % 1% 2.50% 5% Effective Length of Screw (mm) Document Ref: EC-TDSSPROP Page No. 11 of 27

12 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 as shown below. Chart C Safe Working Loads for Freestanding Props with Adjustment Screws ( F X M = 1.65) Note: Overall Prop capacity may be limited by screw jack see Prop Extension Safe Working Load Capacity (to EC3) SP mm Extension SP mm Extension Axial Compression (No Eccentricity) (kn) Axial Tension (No Eccentricity) (kn) End Plate Moment Capacity (knm) End Plate Shear Capacity with maximum moment (kn) End Plate Shear Capacity without moment (kn) Note: The above capacities assume the extensions are connected using 4No M24 grade 8.8 bolts Document Ref: EC-TDSSPROP Page No. 12 of 27

13 3.4 Braced Props s may be assembled and braced with standard Acrow Panels in various ways in order to produce the required pattern of supports. For horizontal spacing the bracing panels are used to space the props at either 2.051m or 3.6m as shown below: 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 1524mm panel) chord bolt connection to the prop body becomes overloaded (see Chart D ). Note that the capacity of the chord bolt connection when using a AB16 panel is much reduced, therefore, wherever possible use AB1 panels as bracing. Use the following diagrams to assist in calculating the effective lengths of the various sections of the prop assembly: 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. Document Ref: EC-TDSSPROP Page No. 13 of 27

14 Le = 876 Le = 913 Le = x Le = 2323 Le = 1162 Le = x Le = 2359 Le = Le = 876 Le = 913 Le = Le = T E C H N I C A L D A T A S H E E T The diagrams of bracing arrangements shown below indicate the effective lengths at the base and mid sections 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. Document Ref: EC-TDSSPROP Page No. 14 of 27

15 Le = 913 Le = 876 Le = 2437 Le = 913 Le = 913 Le = x Le = 3121 Le = x Le = 4645 Le = T E C H N I C A L D A T A S H E E T Document Ref: EC-TDSSPROP Page No. 15 of 27

16 Le = 913 Le = 913 Le = 913 Le = x Le = 2359 Le = x Le = 3121 Le = x Le = 4645 Le = 2323 Le = 876 Le = x Le = 2323 Le = 1162 Le = 3961 T E C H N I C A L D A T A S H E E T Document Ref: EC-TDSSPROP Page No. 16 of 27

17 S.W.L. (kn) - FOS = 1.65 Horizontal Load (kn) unfactored T E C H N I C A L D A T A S H E E T Safe Working Load Charts for Braced Props Chart D - Maximum Horizontal (unfactored) Load/Effective Lengths to ensure Bracing Panel Connection not Overloaded Using AB57 Chord Bolts AB1/AB57 Combination AB16/AB57 Combination Effective Length (m) NOTE: In charts D, E and F the horizontal load H is the load at the top of one prop Chart E - Braced Prop Capacity - (SWL Unfactored) 10mm Load Eccentricity H = 0% H = 1% H = 2.5% H = 5% Effective Length of Prop L e (m) Document Ref: EC-TDSSPROP Page No. 17 of 27

18 S.W.L. (kn) - FOS = 1.65 T E C H N I C A L D A T A S H E E T 2000 Chart F - Braced Prop Capacity - (SWL Unfactored) 25mm Load Eccentricity H = 0% H = 1% H = 2.5% 500 H = 5% Effective Length of Prop (m) Note: Charts E and F DO NOT include the Adjustable Head/Base Units. These are to be checked separately to the Props, refer to Charts A and B. Document Ref: EC-TDSSPROP Page No. 18 of 27

19 3.4.2 Props Braced with Proprietary Push Pull Props Where the s need to be spaced at centres other than 2.051m or 3.6m then proprietary push pull props may be used. The push pull props may be fitted to the body using the SP39 or SP41 bracket. In addition the Header Beams may be braced using SP41 brackets that are bolted to the Header Beam diaphragm bolts. SP41 Universal Push-Pull Adaptor SP39 Push-Pull Adaptor Document Ref: EC-TDSSPROP Page No. 19 of 27

20 Shear Load (kn) unfactored Shear Load (kn) unfactored T E C H N I C A L D A T A S H E E T Safe Working Load Charts for Push Pull Adaptors 180 SP39 - Maximum Shear and Tension to ensure Connecting Bolt not Overloaded Safe Working Loads Under the Line Tension Load (kn) SP41 - Maximum Shear and Tension to ensure AB57 Chord Bolt not Overloaded Safe Working Loads Under the Line Tension Load (kn) Document Ref: EC-TDSSPROP Page No. 20 of 27

21 3.5 Header Beams - Capacities Header Beam Load Capacities Single Beam Twin Beam (SP015,SP016,SP020) (SPA008,SPA009,SPA012) Beam Shear Capacity (kn) Max Beam Bending Resistance (knm) Maximum Reaction (kn) Splice Shear Capacity (kn) Splice Bending Resistance (knm) Notes: Capacities given are for the major Z-Z 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 Header Beam Clamp Plate (SP18) Load Capacities Safe Working Load in Tension of the SP18 Header Beam Clamp and bolt = 65.3kN Maximum Longitudinal Frictional Capacity of the SP18 Header Beam Clamp is as follows: Nominal Value for one clamp hand tightened = 6.3kN Nominal Value for one clamp with the bolt torqued to 500Nm = 16kN Document Ref: EC-TDSSPROP Page No. 21 of 27

22 4.0 Special Applications 4.1 Raking Prop With the standard Swivel Head (SPA001) and Base unit (SPA007) the can easily be adapted to raking applications. Special shear connectors may be required to connect the top of the prop with the soldiers or walings. Restraint required between concrete and wall to prevent uplift. Maximum Deflection for a Single Raking Prop due to Pin Hole Tolerance No of 3048mm Modules) Sag (mm) Thrust Block of concrete or similar, designed with adequate horizontal shear capacity 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. 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. Document Ref: EC-TDSSPROP Page No. 22 of 27

23 4.0 Special Applications 4.2 Towers Plan Bracing of Towers: The prop chord connector (SP007) 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. Tower Bracing Using Acrow Panels: The Body is compatible for bracing using Acrow Panels (AB1 or AB16). The AB1 is fitted with 4 chord blocks and AB16 with 2 chord blocks. Wherever possible the AB1 panel should be used and all 4 chord bolts fitted along each of the panel chords. As the AB16 bracing panel has only 2 chord connection blocks the capacity of a tower only braced with AB16 s is much reduced. Using the Acrow Panels as bracing panels the legs are spaced at either: 2.051m centres (One Acrow Bracing Panel) 3.6m centres (Two Acrow Bracing Panels) Document Ref: EC-TDSSPROP Page No. 23 of 27

24 5.0 Equipment List Part No. Description Weight (kg) Part No. Description Weight (Kg) SPA001 ADJUSTABLE HEAD ASSY SP mm PROP EXTENSION SPA mm MODULE SP034 CANT WALKWAY BRACKET 9.5 SPA mm MODULE SP036 CANT WALKWAY CORNER 9.0 SPA mm EXTENSION SP039 P/P ADAPTOR (PROP) 7.3 SPA005 BASE UNIT SPA mm EXTENSION SP040 75mm JACKING PACK 5.8 SPA007 ADJUSTABLE BASE ASSY SP041 UNIVERSAL P/P ADAPTOR 11.0 SPA008 TWIN HEADER BEAM 4m SP049 50mm SPREADER PLATE 76.0 SPA009 TWIN HEADER BEAM 6m SPA mm HEAD MODULE SP070 SUPER PROP SPACER PLT 5.8 SPA011 MOD SP009 C/W 2NO SP SP071 TWIN CHORD BOLT 0.1 SPA012 TWIN HEADER BEAM 2m SP /4 BSW WASHER 0.05 SP076 TWIN S/PROP BASE/HEADER BEAM SP001 PROP FLAT BASE FEMALE 95.3 SP077 TWIN S/PROP CHORD BOLTS 0.3 SP002 SCREW SOLE PLATE SP mm JACKING PACK 13.4 SP003 ADJUSTMENT SCREWS 98.4 SP mm 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 SP081 SUPERPROP SHEAR PIN CONNECTOR 5.0 SP007 PROP CHORD CONNECTOR 34.9 SP082 1m SUPERPROP HEADER BEAM SP008 BOLT/HSFG WASHERS 0.1 SP083 TRANSFER PLATE 31.0 SP mm PROP EXTENSION AB mm ACROW PANEL SP010 PROP HEAD (MALE) AB mm REINFORCING CHORD 92.0 SP011 SCREW HEAD PLATE 95.3 AB mm ACROW PANEL SP012 PROP FLAT PLATE AB mm REINFORCING CHORD 57.0 SP015 4m HEADER BEAM AB051 ACROW PANEL PIN 2.7 SP016 6m HEADER BEAM 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 KIT 1.0 AB803 ACROW PANEL 700 (HYBRID) AB804 ACROW PANEL 700 (HIGH SHEAR) SP020 HEADER BEAM 2m SP mm 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 SP mm PROP EXTENSION SPSKAT SUPERPROP SKATE ASSEMBLY 97.0 SP mm PROP EXTENSION NB: Stock levels of certain parts listed above are limited please check availability with our engineers. Document Ref: EC-TDSSPROP Page No. 24 of 27

25 6.0 Bolt Application Table 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) mm Bracing Panel to 3048mm Bracing Panel Chord Bolt (AB057 or SP077) & Washer (SP073) 4 Document Ref: EC-TDSSPROP Page No. 25 of 27

26 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. NB: All bolts and connections MUST be fitted as shown above. Document Ref: EC-TDSSPROP Page No. 26 of 27

27 8.0 Design Procedure Design Assumptions: The tables and charts within these data sheets have been derived using values and resistances calculated from the Eurocodes or derived from test, these values have then been modified by the application of suitable factors of safety to produce the Safe Working Loads that appear in these data sheets. 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 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% of the applied vertical loading. 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 bracing 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 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. Document Ref: EC-TDSSPROP Page No. 27 of 27