SANS 1900-2009 Monoplanar prefabricated timber roof trusses (nail-plated)《单面预制木质屋顶架（钉板）》.pdf

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1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-22839-2 SANS 1900:2009Edition 1.2SOUTH AFRICAN NATIONAL STANDARD Monoplanar prefabricated timber roof trusses (nail-plated) Published by S

4、ABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 1900:2009 Edition 1.2 Table of changes Change No. Date Scope 1 2004 Amended to allow for the use of a stick on label for marking, to change the definit

5、ion and requirements for nail plates, and to change the reference to “the” certification mark in annex B to “a” certification mark. 2 2009 Amended to delete reference to the certification mark. Foreword This South African standard was approved by National Committee SABS SC 1008F, Sawn timber and sem

6、i manufactured timber products Prefabricated timber and roof trusses, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in November 2009. This document supersedes SANS 1900:2004 (edition 1.1). A vertical lin

7、e in the margin shows where the text has been technically modified by amendment No. 2. Annex A forms an integral part of this document. Annexes B and C is for information only. SANS 1900:2009 Edition 1.2 1 Contents Page Foreword 1 Scope . 3 2 Normative references 3 3 Definitions 3 4 Requirements 6 5

8、 Inspection 9 6 Methods of test . 9 7 Packing and marking 10 Annex A (normative) Notes to purchasers 11 Annex B (informative) Quality verification of prefabricated timber roof trusses and assessment of compliance . 11 Annex C (informative) Storage, transportation and handling of prefabricated timber

9、 roof trusses . 12 Bibliography. 13 SANS 1900:2009 Edition 1.2 2 This page is intentionally left blank SANS 1900:2009 Edition 1.2 3 Monoplanar prefabricated timber roof trusses (nail-plated) 1 Scope This standard specifies requirements for monoplanar prefabricated timber roof trusses assembled with

10、nail plates. This standard is not applicable to bolted timber trusses manufactured on building sites. NOTE This standard should be read in conjunction with SANS 10243. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of th

11、is standard. All standards are subject to revision and, since any reference to a standard is deemed to be a reference to the latest edition of that standard, parties to agreements based on this standard are encouraged to take steps to ensure the use of the most recent editions of the standards indic

12、ated below. Information on currently valid national and international standards can be obtained from the SABS Standards Division. SANS 1091, National colour standard. SANS 1288, Preservative-treated timber. SANS 1783-1, Sawn softwood timber Part 1: General requirements. SANS 1783-2, Sawn softwood ti

13、mber Part 2: Stress-graded structural timber and timber for frame wall construction. SANS 10005, The preservative treatment of timber. SANS 10243, The manufacture and erection of timber trusses. SANS 3575/ISO 3575, Continuous hot-dip zinc-coated carbon steel sheet of commercial and drawing qualities

14、. 3 Definitions For the purposes of this standard, the definitions given in SANS 10243 and the following definitions apply: 3.1 acceptable acceptable to the authority administering this standard or to the parties concluding the purchase contract, as relevant SANS 1900:2009 Edition 1.2 4 3.2 apex pea

15、k point on a truss where the upper edges of the sloped top chords meet 3.3 bottom chord tie beam horizontal or inclined (e.g. scissors truss) member that establishes the lower edge of a truss and usually carries combined bending and tension stresses 3.4 camber upward vertical displacement built into

16、 a truss bottom chord to compensate for deflection due to self weight 3.5 chord one of the main members that forms the outline of the truss and that is subject to relatively large axial forces and bending moments 3.6 defective prefabricated timber roof truss that fails in one or more respects to com

17、ply with the relevant requirements of this standard 3.7 design rational design any design involving a process of reasoning and calculation and may include any such design based on the use of a code of practice or other relevant technical document, in particular, a design utilizing software produced

18、by the system 3.8 heel truss ends the truss ends, H, where the top and bottom chords connect in double-pitched trusses, or where the end webs join the bottom chord in stub-end or monopitched trusses (see figure 1) 3.9 lot not less than 2 and not more than 500 timber roof trusses of the same design a

19、nd dimensions from one manufacturer, submitted at any one time for inspection and testing 3.10 member part or component which, together with other members, makes up a roof truss (i.e. truss members are the top chords, bottom chords and webs which form the truss) 3.11 nail plate metal connector plate

20、 corrosion-resistant metal plate, punched to form a nail pattern in the plate, used as a connector between the members of a roof truss and whose design values have been properly established by an accredited testing authority Amdt 1 SANS 1900:2009 Edition 1.2 5 3.12 monoplanar truss truss with all ch

21、ords and webs assembled in a single plane (usually associated with nail-plated trusses) 3.13 span truss span the distance, S, along the bottom chord between the heels or truss ends, H, (see figure 1) 3.14 system any natural person, firm, partnership, close corporation or company engaged in the manuf

22、acture, distribution or sale of metal connector plates for the timber truss industry, and who further provides a complete service, i.e. the supply of products, technical support and structural engineering to the truss manufacturer 3.15 top chord rafter horizontal or inclined member that establishes

23、the upper edge of a truss 3.16 web member that joins the top and bottom chords to form the triangular patterns that create truss action, usually subject to tensile or compressive forces. SANS 1900:2009 Edition 1.2 6 Where S is the span; H is the heel or truss end. Figure 1 Truss span 4 Requirements

24、4.1 Roof truss design The design used to manufacture each roof truss in a batch or order shall be a rational design. The design shall include the grade of the timber, the dimensions of the timber, the geometric configuration of all the members and the dimensions and positioning of the nail plates to

25、 be used. SANS 1900:2009 Edition 1.2 7 4.2 Roof truss material 4.2.1 Timber 4.2.1.1 General Each member of timber used in each roof truss shall comply with the requirements of SANS 1783-1 and SANS 1783-2. 4.2.1.2 Timber grade Each member of timber shall be graded and the grade of each member within

26、a roof truss shall be as per the design or of a higher grade than specified in the design. 4.2.1.3 Timber dimensions When determined in accordance with 6.1.1(a), the length, width and thickness of the timber shall be as specified in the design. The allowable tolerances shall be as given in table 1.

27、The maximum difference in thickness of members in a joint area shall be 1,0 mm. Table 1 Permissible tolerances in timber components 1 2 Description Permissible tolerance Length 1 mm/m Width and thickness See SANS 1783-2 4.2.1.4 Cutting and machining of timber The lengths and angles of each timber me

28、mber shall be accurately cut and machined in accordance with the design. 4.2.1.5 Preservative treatment of timber When specified by the purchaser (see A.2), or where necessary (see A.1 and SANS 10005), each piece or unit of timber used in a roof truss shall be preservative treated in accordance with

29、 SANS 1288. 4.2.2 Nail plates (metal connector plates) 4.2.2.1 General Each nail plate used for the jointing of members within a roof truss shall be acceptable and shall comply with the requirements given in 4.2.2.2 and 4.2.2.3. 4.2.2.2 Construction Each nail plate shall a) be made of either galvani

30、zed steel, stainless steel or an aluminium-zinc alloy, SANS 1900:2009 Edition 1.2 8 b) in the case of galvanized steel nail plates, have a zinc coating with a minimum corrosion resistance of class Z275 of SANS 3575, c) be of nominal thickness 1,0 mm with a tolerance of 0,05 mm, and d) have either pu

31、nched nails or punched holes for loose nails, the design values of which have been determined through tests carried out by an accredited testing laboratory. Amdt 1 4.2.2.3 Dimensions The length and width, determined in accordance with 6.1.2, of each nail plate used in a roof truss shall be at least

32、as specified in the design, with a tolerance of mm. 4.3 Roof truss (final product) 4.3.1 General Each completed roof truss in each batch or order shall comply with the requirements given in 4.3.2 to 4.3.7. 4.3.2 Timber defects There shall be no wane, dead knots or resin infiltration within the conne

33、ctor plate area unless a larger connector plate is used to compensate for the nails that have become ineffective in that area. 4.3.3 Nail plates Only nail plates as specified in 4.2.2 and provided by the same system as the design, shall be used in a roof truss and shall be: a) at least the dimension

34、s as specified in the design; b) positioned and oriented as specified in the design; and c) applied in such way as to provide a firm, even contact between the faces of both the nail plate and the timber so that the teeth are not flattened and that all the teeth are fully embedded in all the members

35、of a joint, except in the case of a tolerance difference in the thickness of the members at a node, where the teeth shall be fully embedded in at least one member with a maximum clearance of 1,0 mm between the nail plate and the other member(s) at that joint. In the case of joints where the timber i

36、s damaged due to splitting, the splits shall not exceed the requirements for splits as specified in SANS 1783-2. 4.3.4 Joint clearance In open joints resulting from inaccuracies in cutting and assembly, the joint clearance shall not exceed 2,0 mm except in joint lengths greater than 300 mm where a m

37、aximum of 5,0 mm is allowed. At least one end or corner of each member shall be in contact with adjoining members at the node. 4.3.5 Straightness of a roof truss (overall bow) When determined in accordance with 6.2, no point of a truss shall be out of plane of the truss by more than 50 mm or L/100,

38、whichever is the greater, where L is the length of the chord. 0 -2 SANS 1900:2009 Edition 1.2 9 4.3.6 Design dimensions of a roof truss The dimensions of a roof truss, determined in accordance with 6.1.1(a) to 6.1.1(e), shall be as specified in the design. The permissible deviations from the design

39、dimensions shall comply with the values given in table 2. Table 2 Permissible deviations in timber roof trusses 1 2 Description Permissible deviations Span 10 mm Height a) Individual trusses b) Maximum difference between similar trusses in a building 20 mm 10 mm Joint position (measured on centre li

40、ne of members), max. 25 mm Camber (when specified) 10 % (of the specified design value) 4.3.7 Position of the apex The position of the apex shall be as specified in the design. The apexes of trusses in a sample shall not deviate from one another by more than 20 mm in any direction. 5 Inspection Visu

41、ally inspect each roof truss in the sample drawn in accordance with B.2.1 for compliance with those requirements given in 4.1 to 4.3 for which methods to assess compliance are not given in clause 6. 6 Methods of test 6.1 Dimensions Determine the dimensions of the different components of a roof truss

42、 in accordance with 6.1.1 and 6.1.2. 6.1.1 Dimensions of timber components and roof trusses Measure the dimensions of a prefabricated roof truss as follows: a) length, width and thickness of each member to the nearest 1 mm; b) take as the overall span the horizontal distance between the intersection

43、s of the lower edges of the top and bottom chords, but in the case of a straight bottom chord, take the length of the bottom edge of the bottom chord to the nearest 1 mm; c) take as the overall height the vertical distance between the intersection of the lower edges of the top and bottom chord and t

44、he highest point of the truss (apex); d) when measuring the position of the webs, use the centre lines of the webs and the intersections of the outer edges of the top and bottom chords; SANS 1900:2009 Edition 1.2 10 e) when relevant, measure the camber as the vertical distance between the intersecti

45、on of the lower edges of the top and bottom chord and the lower edge at the mid-length of the bottom chord. 6.1.2 Dimensions of nail plates Measure the width and length of a nail plate to the nearest 1 mm. 6.2 Straightness Place the truss flat on a hard, level surface and measure to the nearest 1 mm

46、 the extent to which any part of the truss is out of the longitudinal plane of the truss. Repeat this procedure with the truss overturned. 6.3 Joint clearance Measure the greatest clearance between two members in a joint area to the nearest 1 mm. 7 Packing and marking 7.1 Packing When prefabricated

47、timber roof trusses are dispatched, they shall be so secured as to withstand normal handling hazards. Guidelines on the storage, handling and transportation are given in annex C. 7.2 Marking 7.2.1 Methods Each completed roof truss shall be marked in a legible, indelible and permanent way, in strong

48、blue (colour No. F11 of SANS 1091), using one of the following acceptable methods: a) an ink stamp; or b) a durable self adhesive label. Amdt 1 7.2.2 Position of marking The marking shall be placed on one face of the bottom chord of each roof truss, in a position parallel to its longitudinal axis, a

49、pproximately in the centre of the face, not obscuring the marking of the stress grade of the timber as specified in SANS 1783-2. 7.2.3 Information Each completed truss shall bear the following minimum information. a) the manufacturers name, trade name or trade mark; b) the last two digits of the year in which the roof truss was manufactured (01 for 2001);and c) the batch number or job number. Include additional information as required (see A.2(b): Amdt 1 SANS 1900:2009 Edition 1.2 11 Annex A (normative) Notes to purchasers A.1 The following requirement shall be sp