SANS 745-2-2008 Structural laminated veneer lumber Part 2 Determination of structural properties - Test methods《结构层积单板 第2部分 结构特性测定-试验方法》.pdf

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 978-0-626-22181-2 SANS 745-2:2008Edition 1AS/NZS 4357.2:2005Edition 1SOUTH AFRICAN NATIONAL STANDARD Structural laminated veneer lumber Part 2: Dete

4、rmination of structural properties Test methods This national standard is the identical implementation of AS/NZS 4357.2:2005 and is adopted with the permission of Standards Australia and Standards New Zealand. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretori

5、a 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 745-2:2008 Edition 1 AS/NZS 4357.2:2005 Edition 1 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee SABS SC 1008A, Sawn timber and semi-manufactured timber p

6、roducts Structural timber, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published in November 2008. AS/NZS 4357.2:2005Australian/New Zealand StandardTMStructural laminated veneer lumber Part 2: Determination

7、 of structural properties Test methods First published as AS/NZS 4357.2:1995 Revised and redesignated as AS/NZS 4357.02005 COPYRIGHT Standards Australia/Standards New Zealand All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanic

8、al, including photocopying, without the written permission of the publisher Jointly published by Standards Australia, GPO Box 476, Syndey, NSW 2001 and Standards New Zealand, Private Bag 2439, Wellington 6020 ISBN 0 7337 6812 1 AS/NZS 4357.2:2005 2 PREFACE This Standard was prepared by the Joint Sta

9、ndards Australia/Standards New Zealand Committee TM-008, Plywood Timber Products. This standard incorporates Amendment No. 1 (July 2006). The changes required by the Amendment are indicated in the text by a marginal bar and amendment number against the clause, note, table, figure or part thereof aff

10、ected. The objective of this Standard is to provide test methods for the determination of structural properties of structural laminated veneer lumber (LVL), which will replace the methods used in the past specified in AS/NZS 4063, Timber Stress-graded In-grade strength and stiffness evaluation, for

11、sawn timber. This Standard specifies test methods only. Characteristic structural properties will be determined using the test results generated by the test methods specified in this Standard and processed through the methods specified in the companion Standard AS/NZS 4357.3, Determination of struct

12、ural properties Evaluation method. This Standard development has relied upon proven test methods for solid section timber and glue laminated timber products specified in AS/NZS 4063, prEN 408, Timber structures Structural timber and glued laminated timber Determination of some physical and mechanica

13、l properties, ASTM D198, Standard Test Methods of Static Tests of Lumber in Structural Sizes, and ASTM D143, Standard Test Methods for Small Clear Specimens of Timber. This Standard is Part 2 of the AS/NZS 4357 series, Structural laminated veneer lumber, which is comprised of the following parts: AS

14、/NZS 4357 Structural laminated veneer lumber 4357.0 Part 0: Specifications (Revision of AS/NZS 4357:1995) 4357.1 Part 1: Method of test for measurement of dimensions and shape 4357.2 Part 2: Determination of structural properties Test methods (this Standard) 4357.3 Part 3: Determination of structura

15、l properties Evaluation methods 4357.4 Part 4: Determination of formaldehyde emissions The test methods are currently being prepared for compression and tension perpendicular to grain, and bearing. While these test methods are under development, other recognized Standards, e.g., ASTM D 143, may be u

16、sed 3 AS/NZS 4357.2:2005 CONTENTS Page 1 SCOPE . 4 2 REFERENCED DOCUMENTS 4 3 DEFINITIONS 4 4 NOTATION . 4 5 SAMPLING . 4 6 DETERMINATION OF DIMENSION OF TEST PIECES . 5 7 DETERMINATION OF MOISTURE CONTENT OF TEST PIECES I 8 CONDITIONING OF TEST PIECES 8 9 DETERMINATION OF APPARENT MODULUS OF ELASTI

17、CITY (E) IN BENDING 10 DETERMINATION OF TRUE BENDING MODULUS AND SHEAR MODULUS OF ELASTICITY FOR BEAMS 11 DETERMINATION OF BENDING STRENGTH . 12 DETERMINATION OF MODULUS OF ELASTICITY IN TENSION PARALLEL TO GRAIN . 13 DETERMINATION OF TENSILE STRENTH PARALLEL TO GRAIN . 14 DETERMINATION OF MODULUS O

18、F ELASTICITY IN COMPRESSION PARALLEL TO GRAIN . 15 DETERMINATION OF COMPRESSION STRENGTH PARALLEL TO GRAIN 16 DETERMINATION OF SHEAR STRENGTH . 17 TEST REPORT STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND Australian/New Zealand Standard Structural laminated veneer lumber Part 2: Determination of structu

19、ral properties Test methods 1 SCOPE This Standard specifies test methods for determining the following properties of structural laminated veneer lumber (LVL) manufactured in accordance with AS/NZS 4357.0: (a) Apparent modulus of elasticity. (b) True bending modulus and shear modulus of elasticity fo

20、r beams. (c) Bending strength. (d) Modulus of elasticity in tension parallel to the grain, and tension strength parallel to the grain. (e) Modulus of elasticity in compression parallel to the grain, and compression strength parallel to the grain. (f) Shear strength. NOTES 1 This Standard does not sp

21、ecify test methods for the determination of joint characteristics, which should be carried out in accordance with AS 1649. 2 The test methods specified in this Standard may be used for quality control testing. 2 REFERENCED DOCUMENTS The following documents are referred to in this Standard: AS 1649 T

22、imber Methods of test for mechanical fasteners and connectors Basic working loads and characteristic strengths 1720 Timber structures 1720.1 Part 1: Design methods AS/NZS 2098 Methods of test for veneer and plywood 2098.1 Moisture content of veneer and plywood 4357 Structural laminated veneer lumber

23、 (LVL) 4357.0 Part 0: Specification 4491 Timber Glossary of terms in timber-related Standards NZS 3603 Timber Structures Standard 3 DEFINITIONS For the purpose of this Standard the definitions in AS/NZS 4491 apply. 5 AS/NZS 4357.2:2005 COPYRIGHT 4 NOTATION Where not otherwise defined in the specific

24、 test method, the symbols used in this Standard are as follows: A = Cross-sectional area, in millimetres square E = apparent modulus of elasticity in bending, in megapascals Et,0= modulus of elasticity in tension parallel to grain, in megapascals Etrue= true modulus of elasticity in bending, in mega

25、pascals G = shear modulus of elasticity for beams, in megapascals P = load, in newtons Pmax.= maximum load, in newtons Rb= bending strength, in megapascals Rc,0= compression strength parallel to grain, megapascals Rc,90= compression strength perpendicular to the grain, megapascals Rs= shear strength

26、, megapascals Rt,0= tension strength parallel to grain, megapascals = deflection, in millimetres 5 SAMPLING 5.1 Population determination The reference population shall be clearly defined since the test results, hence characteristic properties, apply only to that population. The population determinat

27、ion shall be defined as a minimum in accordance with the characteristics required in AS/NZS 4357.0. The reference population is specific to the LVL as specified in AS/NZS 4357.0 and the results of testing shall apply only to the specified reference population. The sample to be tested shall be chosen

28、 as to be representative of the reference population. Considerable care shall be taken to ensure all strength-reducing characteristics, which affect or concernably might affect strength or stiffness, and are distributed within the sample in much the same frequency as they are to be found within the

29、reference population. 5.2 Sample size The minimum sample used shall not be less than 30 specimens. 5.3 Sampling plan A sampling plan shall be prepared to ensure the sample is representative of the product made to the manufacturing specification. 5.4 Test pieces In order to simulate in-service condit

30、ions, test pieces shall be cut from random locations within the specimen of the sampled LVL. AS/NZS 4357.2:2005 6 COPYRIGHT 6 DETERMINATION OF DIMENSIONS OF TEST PIECES The dimensions of test pieces shall be measured to accuracy as follows: (a) For dimension 150 mm, but 400 mm . 1 mm. All measuremen

31、ts shall be made after the test pieces have been conditioned as specified in Clause 0. Width and depth dimensions shall be the average of three measurements taken at three different positions within the middle third of the test pieces. Where possible, the measurements shall not be taken within 150 m

32、m of the ends of the test piece. 7 DETERMINATION OF MOISTURE CONTENT OF TEST PIECES The moisture content of the test pieces shall be determined in accordance with AS/NZS 2098.1, on a section of the test piece of full cross-section. For strength tests, the section shall be taken as close as possible

33、to the fracture. 8 CONDITIONING OF TEST PIECES Before testing, the test pieces shall be conditioned in an atmosphere of 20 3C and 65 5% relative humidity. A test piece is deemed to be conditioned when it attains constant mass. Constant mass is deemed to be attained when the results of at least three

34、 successive weighings indicate that the moisture content has stablized within 0.5% for at least a 48 h period. If test pieces are not conditioned, the moisture content at time of test shall be within 2% of the moisture content of a sub-sample of the same product and grade, conditioned using the meth

35、od above. 9 DETERMINATION OF APPARENT MODULUS OF ELASTICITY (E) IN BENDING NOTE The results obtained using this test method are used to derive the modulus of elasticity, E, for design of rectangular beams in accordance with AS 1720.1 or NZS 3603. 9.1 Length of test piece The minimum length of test p

36、iece shall be 20 times the depth of the section. Where this is not possible the length of the test pieces shall be reported. 9.2 Test configuration The test piece shall be symmetrically loaded at two points (four point bending test) over a span 18 times the nominal depth as shown in figure 1. The te

37、st piece shall be simply supported. Lateral restraint shall be provided as necessary to prevent buckling. This restraint shall permit the piece to deflect without significant frictional resistance. The loading equipment used shall be capable of measuring the load to an accuracy of 1%. NOTES 1 If the

38、 test configuration differs from the above in any way, then the difference should be recorded and adjustment factors should be determined. 2 Bearing plates should be sized to minimize the indentation that may occur at the bearing points. 7 AS/NZS 4357.2:2005 COPYRIGHT 9.3 Procedure The test procedur

39、e shall be as follows: (a) Apply the load at a constant rate. The rate of movement of the loading head shall be not greater than 0.01 d mm/min (see Figure 1). A1 (b) Measure the deformation () at the centre of the span at the neutral axis or at the middle of the bottom edge (see Note). When is measu

40、red at the neutral axis, it shall be the mean of measurements made on both sides of the test piece and relative to the mid-height of the test pieces at the supports. Deformations shall be determined to an accuracy of 1%. NOTE The deformation () includes any indentations that might occur at the suppo

41、rts and loading points. NOTE = Mid-point deflection at load P. FIGURE 1 TEST ARRANGEMENT FOR MEASURING APPARENT MODULUS OF ELASTICITY IN BENDING 9.4 Expression of results The apparent modulus of elasticity (E) in bending is determined from the following equation: 3s2 1321L( )23=108 ()PPEbd . . . 9.4

42、 where P2 P1increment of load on the straight line portion of the load deflection curve, in newtons (see Figure 2) 2 1increment in deflection corresponding to P2 P1, in millimetres (see Figure 2) AS/NZS 4357.2:2005 8 COPYRIGHT FIGURE 2 LOAD-DEFORMATION GRAPH WITHIN THE RANGE OF ELASTIC DEFORMATION 1

43、0 DETERMINATION OF TRUE BENDING MODULUS AND SHEAR MODULUS OF ELASTICITY FOR BEAMS 10.1 General The determination of the true bending modulus of elasticity and the shear modulus of elasticity for beams involves testing each test piece in the following two tests: (a) Four-point bending test (see Claus

44、e 10.3.1). (b) Three-point bending test (see Clause 10.3.2). In both tests, the slope of the linear portion of the load-deflection graph is required. NOTE The accuracy of the determination of true bending modulus and shear modulus of elasticity is sensitive to the consistency of error in the measure

45、ment of load and deformation between both tests. Therefore, it is recommended that the following be taken into consideration: (a) The same load and deflection measuring equipment are used in both tests. (b) Rates of application of load are consistent. (c) Bearing plates are the same, and are adequat

46、e to minimize local indentation. (d) The test piece is positioned and oriented the same way up in each test. (e) Testing is performed under similar ambient conditions. (f) The time interval between each type of test is limited, to minimize differences that may result from changes in test piece moist

47、ure content and temperature. 10.2 Length of test piece The minimum length of test piece shall be 20 times the depth of the section. Where this is not possible, the length of the test pieces shall be reported. The same test pieces shall be used for the four-point bending test and the three-point bend

48、ing test. 9 AS/NZS 4357.2:2005 COPYRIGHT 10.3 Procedure 10.3.1 Four-point bending test The test piece shall be tested in four-point bending using the test arrangement described in Figure 1 and the procedure given in clause 0. 10.3.2 Three-point bending test 10.3.2.1 Test configuration The test piece

49、 shall be symmetrically loaded at three points (three-point bending test) as shown in Figure 3. The loading equipment used shall be capable of measuring the load to an accuracy of 1 %. NOTE Bearing plates should be sized to minimize the indentation that may occur at the bearing points. = Mid-point deflection at load P. FIGURE 3 TEST ARRANGEMENT FOR THREE-POINT TEST 10.3.2.2 Procedure The test procedure shall be as follows: (a) Apply the load at mid-span, at a constant rate. The test span shall be one half the span of