1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 4074:2000 ICS 91.220 N
2、O COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Specification for steel trench strutsThis British Standard, having been prepared under the direction of the Sector Committee for Building and Civil Engineering, was published under the authority of the Standards Committee and come
3、s into effect on 15 October 2000 BSI 10-2000 First published October 1966 Second edition April 1982 Third edition October 2000 The following BSI references relate to the work on this standard: Committee reference B/514/28 Draft for comment 97/109950 DC ISBN 0 580 33214 4 BS 4074:2000 Amendments issu
4、ed since publication Amd. No. Date Comments Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee B/514/28, Props, tubes and couplers, upon which the following bodies were represented: Health and Safety Executive UK Steel Assoc
5、iation Co-opted memberBS 4074:2000 BSI 10-2000 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Designation 2 5 Materials 3 6 Construction 3 7 Strength 6 8 Marking 7 Annex A (informative) Examples of calculations on trench str
6、ut pin connections 8 Annex B (informative) Typical materials 8 Annex C (normative) Test for unintentional disengagement 9 Bibliography 11 Figure 1 Steel trench strut 3 Figure 2 Thread and collar nut clearances 4 Figure 3 Calculated thickness, t, of threaded tube 5 Figure 4 Dimensions of collar nut 6
7、 Table 1 Principal dimensions of trench struts 2 Table 2 Minimum yield strength 6 Table B.1 Typical materials 8ii BSI 10-2000 BS 4074:2000 Foreword This British Standard has been prepared by Subcommittee B/514/28. Together with BS EN 1065:1999, it supersedes BS 4074:1982, which is withdrawn. Safe wo
8、rking loads of trench struts are not specified in this standard. It is recommended that the axial concentric compression working load of trench struts be less than 30 kN. The principal changes from the 1982 edition are as follows. a) Adjustable telescopic steel props (previously known as metal props
9、), which are primarily intended for use in falsework and other structures requiring temporary compression support members, are now covered in BS EN 1065:1999. b) The title has been changed to Specification for steel trench struts to describe the common usage of the product more accurately. c) The de
10、tails for designing a trench strut according to its geometric characteristics have been amended to include thinner-walled thread-rolled outer tubes and thinner-walled higher-strength inner tubes, which will result in lighter, more economical designs. d) Cut threads on the outer tubes are no longer i
11、ncluded. e) A test to verify that the component parts of trench struts do not become inadvertently disengaged in use has been added. f) There is now a requirement aimed at preventing shear failure caused by any reduction in the pin cross-section. g) There is now a requirement to mark trench struts w
12、ith the year of manufacture. The previously accepted characteristic resistance, f k , of trench struts has been retained at 50.0 kN. Examples of calculations on trench strut pin connections are given in annex A. A British Standard does not purport to include all necessary provisions of a contract. U
13、sers of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 11 and a back cover. The BS
14、I copyright notice displayed in this document indicates when the document was last issued.BS 4074:2000 BSI 10-2000 1 1 Scope This British Standard specifies requirements for adjustable compression tubular steel trench struts. The requirements relate to materials, design, dimensions, strength and res
15、istance to unintentional disengagement. The dimensions specified include the lengths fully open and fully closed. The standard does not give information on the use of trench struts. NOTE 1 The requirements of this standard are intended to ensure that the struts will have a characteristic resistance
16、of 50 kN at all extensions. The standard does not specify a requirement for this characteristic resistance or a means of verifying it. Annex A gives examples of calculations on trench strut pin connections. NOTE 2 Various protective finishes are specified in BS EN 1065:1999. 2 Normative references T
17、he following normative documents contain provisions which, through reference in this text, constitute provisions of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the public
18、ation applies. BS EN 1562, Founding Malleable cast irons. BS EN 1563, Founding Spheroidal graphite cast iron. 3 Definitions For the purposes of this standard, the following definitions apply. 3.1 trench strut compression member, of adjustable length, intended for use as a temporary horizontal suppor
19、t for building and civil engineering works NOTE See Figure 1. 3.2 claw plate plate with upturned corners, which is welded to a tube end and is intended to grip a timber waler 3.3 collar nut internally threaded casting, incorporating a handle and a podger hole, providing fine adjustment to a trench s
20、trut 3.4 outer tube larger diameter tube, one end of which is threaded and slotted 3.5 inner tube smaller diameter tube provided with holes for the coarse adjustment of the trench strut 3.6 length fully open distance measured between the outer faces of the claw plates when the pin is in the hole fur
21、thest from the inner tube claw plate and the collar nut is at its maximum distance from the outer tube claw plate 3.7 length fully closed distance measured between the outer faces of the claw plates when the pin is in the hole nearest the inner tube claw plate and the collar nut is at its minimum di
22、stance from the outer tube claw plate2 BSI 10-2000 BS 4074:2000 3.8 pin component which is inserted through one of the holes in the inner tube, via the slot in the outer tube, and rests on the collar nut, to secure the inner tube at a particular extension and to transfer forces 3.9 tube overlap leng
23、th of inner tube remaining in the outer tube 4 Designation The designation of a trench strut shall consist of the following: a) the description “trench strut”; b) the number and date of this British Standard, i.e. BS 4074:2000; c) the size number as given in Table 1, according to the length fully op
24、en. EXAMPLE A trench strut with a length fully closed of 0.3 m, a length fully extended of 0.48 m and a minimum tube overlap of 117 mm would be designated as follows: Table 1 Principal dimensions of trench struts Size Length m Minimum tube overlap Fully closed Fully open mm 0 0.30 0.05 0.48 0.05 117
25、 1 0.45 0.05 0.68 0.05 155 2 0.68 0.05 1.06 0.05 155 3 1.06 0.05 1.67 0.05 155 NOTE These requirements are intended to ensure that the struts will have a characteristic resistance of 50 kN at all extensions.BS 4074:2000 BSI 10-2000 3 Handle Pin Clawplate Collarnut Nailholes Lengthfullyopen/fullyclos
26、ed Outertube Innertube Adjustmenthole Clawplate w w Holeforpodger Figure 1 Steel trench strut 5 Materials 5.1 Tubes, claw plates, pins and handles shall be manufactured from steels capable of meeting the strength requirement given in clause 7 and having a specified minimum yield strength (R eH ) not
27、 exceeding 400 N/mm 2 . NOTE Some grades of steel specified within the standards listed in annex B will meet this requirement. Materials for tubes and claw plates shall be suitable for welding. 5.2 Collar nuts shall be manufactured from cast iron conforming to either BS EN 1562 or BS EN 1563. 6 Cons
28、truction 6.1 Dimensions 6.1.1 Principal dimensions shall conform to those specified for one of the sizes given in Table 1, subject to a tolerance of 50 mm on the length fully open and the length fully closed. 6.1.2 The inner tube shall have a nominal outside diameter of 48.3 mm and a minimum nominal
29、 wall thickness of 3.2 mm. 6.1.3 The coarse adjustment holes in the inner tube shall be concentric with the tubes cross-sectional axis to within 0.5 mm. The holes shall be drilled and shall not exceed 17.8 mm in diameter. 6.1.4 The outer tube shall have a nominal outside diameter of 60.3 mm and a no
30、minal wall thickness of 3.6 mm. 6.1.5 The thread on the outer tube shall be generated by a thread rolling process and the profile shall be trapezoidal. The lead of the thread shall be not less than 6 mm nor greater than 10 mm. The nominal depth of the thread shall be not less than 0.25 times the nom
31、inal pitch of the thread. The clearances between the outer tube thread and the collar nut thread shall conform to Figure 2.4 BSI 10-2000 BS 4074:2000 Dimensions in millimetres 0.5 0.5 0.01 Outertube Collarnut Concentricconfiguration Eccentricconfiguration Figure 2 Thread and collar nut clearances Th
32、e calculated thickness, t, of the threaded tube, shown in Figure 3, shall be not less than 2.5 mm. Thickness t is calculated as follows: t = c2 b av 2 where c is the thread root diameter; b av is the mean bore, calculated as follows: b av = b min + b max 2 where b min is the minimum bore; b max is t
33、he maximum bore.BS 4074:2000 BSI 10-2000 5 b b t b c av max min Figure 3 Calculated thickness, t, of threaded tube 6.1.6 Claw plates shall have a minimum thickness of 6.0 mm and a minimum width, w (see Figure 1), of 75 mm. They shall be provided with a claw at each of the four corners, together with
34、 a minimum of two diametrically opposed holes of at least 6 mm diameter (see Figure 1). NOTE Additionally, claw plates may be provided with a centrally positioned hole for particular purposes. 6.1.7 Claw plates shall be positioned centrally on the tubes by means of a continuous ring with a minimum t
35、hroat thickness of 2 mm, fillet welded, such that the centre of the claw plate is within 3 mm of the longitudinal axis of the tube to which it is attached. 6.1.8 Claw plates shall be welded square to the axis of the tube, subject to a maximum tolerance of 18. 6.1.9 The pin shall have a minimum diame
36、ter of 15 mm, and a minimum length of 90 mm which can contact the flange of the collar nut. The pin shall be held captive to the trench strut. 6.1.10 Where a pin has any reduction in its cross-sectional area (such as holes for cables or chains), a means shall be provided to ensure that this portion
37、of the pin is located outside the collar nut major diameter when the pin is fully inserted. 6.1.11 The collar nut shall be provided with a pivoting handle at least 180 mm long. The nominal diameter of the handle shall be at least 15 mm. Diametrically opposite the handle, the collar nut shall have a
38、hole with a minimum diameter of 16 mm for use with a podger (see Figure 1). 6.1.12 The flange of the collar nut on which the pin bears shall have a minimum outside diameter of 76 mm and a minimum thickness of 5 mm (see Figure 4). The thread in the collar nut shall engage the thread on the outer tube
39、 by at least 30 mm and with at least four complete turns of the collar nut thread. The collar nut shall run freely on the outer tube thread.6 BSI 10-2000 BS 4074:2000 Dimensions in millimetres 5 76 30 Figure 4 Dimensions of collar nut 6.2 Finish Sharp edges and burrs shall be removed. Components sha
40、ll be finished so that they are able to move freely within each other. NOTE This standard does not specify requirements for protective finishes. If no other finish is specified, it is recommended that trench struts be painted. Attention is drawn to the range of protective finishes specified in BS EN
41、 1065:1999 for adjustable telescopic steel props. 6.3 Length adjustment 6.3.1 Each trench strut shall incorporate a means of length adjustment, with provision for both coarse and fine adjustment, which shall allow adjustment of the trench strut over the range of lengths given in Table 1. Length adju
42、stment shall be by means of a collar nut and thread, in conjunction with a pin inserted through slots in the outer tube and holes in the inner tube. 6.3.2 The effective length of the outer tube slots shall be greater than the distance between the centres of adjacent holes in the inner tube. 6.3.3 Wh
43、en the trench strut is in the fully extended position, the minimum tube overlap shall conform to Table 1. 6.4 Unintentional disengagement Trench struts shall be provided with a means of preventing the two tubes from unintentional disengagement. When the trench strut is tested in accordance with anne
44、x C, the inner tube shall remain captive to the outer tube. 7 Strength The minimum yield strength of the outer tube, inner tube, claw plates and pin shall conform to Table 2. Table 2 Minimum yield strength Component Minimum yield strength N/mm 2 Symbol Outer tube 190 R eH Inner tube 281 R eH Claw pl
45、ates 235 R eH Pin 280 R eBS 4074:2000 BSI 10-2000 7 1) Marking BS 4074:2000 on or in relation to a product represents a manufacturers declaration of conformity, i.e. a claim by or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is sole
46、ly the claimants responsibility. Such a declaration is not to be confused with third-party certification of conformity. 8 Marking Trench struts shall be marked with at least the following information: a) the number and date of this British Standard, i.e. BS 4074:2000 1) ; b) the manufacturers or sup
47、pliers name or trade mark; c) the year of manufacture (last two digits). The marking shall be impressed or embossed on the trench strut or on a steel plate welded to the trench strut. It shall be legible after any protective coating has been applied. The height of the characters shall be at least 4
48、mm and their depth at least 0.2 mm.BS 4074:2000 8 BSI 10-2000 Annex A (informative) Examples of calculations on trench strut pin connections NOTE The equations given in this annex are based on those given in BS EN 1065:1999, and are included for the convenience of the user of this standard. A.1 Shea
49、r resistance of pin The total shear resistance (R s.p ) of the pin is given by: R s.p = (0.63 A s 3 R m 3 2) $ (f k 3 1.14) where R m is the minimum specified tensile strength of the pin material; A s is the cross-sectional area of the pin; f k is the characteristic resistance of the trench strut. A.2 Bearing resistance of holes in inner tube The total bearing resistance (R b.t ) of the inner tube holes is given by: R b.t = (2.123 R eH 3 23 t3 d) $ (f k 3 1.14) where R eH is the minimum speci
