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1、BRITISH STANDARD BS EN 789:1996 Timber structures Test methods Determination of mechanical properties of wood-based panels The European Standard EN 789:1995 has the status of a British Standard ICS 79.040; 91.080.20 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Unco
2、ntrolled Copy, (c) BSI BS EN 789:1996 This British Standard, having been prepared under the direction of the Sector Board for Building and Civil Engineering, was published under the authority of the Standards Board and comes into effect on 15 July 1996 BSI 07-1999 The following BSI references relate
3、 to the work on this standard: Committee reference B/518/1 Draft for comment 92/16274 DC ISBN 0 580 25872 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/518, Structural timber, to Subcommittee B/518/1, Test methods,
4、upon which the following bodies were represented: Department of the Environment (British Board of Agrment) Department of the Environment (Building Research Establishment) Institution of Civil Engineers Institution of Structural Engineers Timber Research and Development Association Wood Panel Industr
5、ies Federation Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 789:1996 BSI 07-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 Text of
6、EN 7893 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 789:1996 ii BSI 07-1999 National foreword This British Standard has been prepared by Subcommittee B/518/1, and is the English language version
7、of EN 789:1995 Timber structures Test methods Determination of mechanical properties of wood-based panels, published by the European Committee for Standardization (CEN). The standard describes tests specifically designed for establishing the characteristic values of the mechanical properties of wood
8、-based panels used in load-bearing timber structures. It does not supersede any existing British Standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British St
9、andard does not of itself confer immunity from legal obligations. Cross-references Publication referred toCorresponding British Standard EN 322:1992BS EN 322:1993 Wood-based panels. Determination of moisture content EN 323:1992BS EN 323:1993 Wood-based panels. Determination of density EN 325:1992BS
10、EN 325:1993 Wood-based panels. Determination of dimensions of test pieces EN 1058:1995BS EN 1058:1996 Wood-based panels. Determination of characteristic values of mechanical properties and density Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN t
11、itle page, pages 2 to 16, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+
12、00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 789 December 1995 ICS 71.080.20; 79.040 Descriptors: Timber construction, wooden boards, tests, determination, mechanical properties, flexural strength, tensile strength, compressive strength English version
13、Timber structures Test methods Determination of mechanical properties of wood-based panels Structures en bois Mthodes dessai Dtermination des proprits mcaniques des panneaux base de bois Holzbauwerke Prfverfahren Bestimmung der mechanischen Eigenschaften von Holzbauwerkstoffen This European Standard
14、 was approved by CEN on 1995-11-04. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nat
15、ional standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and n
16、otified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kin
17、gdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and its members Ref.
18、 No. EN 789:1995 E Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 789:1995 BSI 07-1999 2 Foreword This European Standard has been prepared by the Technical Committee CEN/TC 124, Timber Structures, of which the secretariat is held by DS.
19、This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 1996, and conflicting national standards shall be withdrawn at the latest by June 1996. In accordance with the CEN/CENELEC Internal Regulations
20、, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword2 1Scope3 2Normative referenc
21、es3 3Definitions3 4Symbols3 5Sampling3 6Preparation of test pieces4 7Bending properties4 8Compression properties6 9Tension properties8 10Test report9 Annex A (normative) Compression test pieces10 Annex B (normative) Panel shear properties10 Annex C (normative) Planar shear properties14 Figure 1 Exam
22、ple of a cutting schedule5 Figure 2 Arrangement for bending test6 Figure 3 Load-deflection or deformation graph within the range of elastic deformation7 Figure 4 Arrangement for compression test8 Figure 5 Arrangement for tension test9 Figure A.1 The form of test piece from panels having a thickness
23、t1 of 40 mm or greater10 Figure A.2 Examples of test pieces from panels having a thickness of less than 40 mm12 Figure B.1 Arrangement for panel shear test 13 Figure C.1 Arrangement for planar shear test15 Table A.1 Typical size of test pieces from panels having a thickness in the range of 6 mm to 4
24、0 mm11 Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 789:1995 BSI 07-19993 1 Scope This standard specifies test methods for determining some mechanical properties of commercial wood-based panel products for use in load-bearing timber st
25、ructures. These properties are intended for the calculation of characteristic values for use in obtaining material design values. For each type and grade of panel product, as defined for example in an EN wood-based panel standard, it is necessary to determine characteristic values of mechanical prop
26、erties to enable it to be used for structural purposes. This standard details the necessary testing which may only need to be carried out once for each product, unless there is a reason to suspect a significant change has occurred in the properties of the product. This standard is not intended to be
27、 used for quality control testing, for which smaller test pieces than specified herein, are adequate. Due to the limited experience in use with the tests, the test methods for panel and planar shear are included in Annex B and Annex C (normative). 2 Normative references This European Standard incorp
28、orates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this Europ
29、ean Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 322, Wood-based panels Determination of moisture content. EN 323, Wood-based panels Determination of density. EN 325, Wood-based panels Determinati
30、on of dimensions of test pieces. EN 1058, Wood-based panels Determination of characteristic values of mechanical properties and density. 3 Definitions For the purposes of this standard, the following definitions apply: 3.1 specimen piece of the panel from which a test piece will be fabricated 3.2 te
31、st piece specimen or aggregate of parts from a sample fabricated to the size and shape required for testing 4 Symbols Subscripts applied to loads, capacities, strengths, stiffness, and moduli of elasticity: 5 Sampling 5.1 Sampling of panels All panels in a sample shall be of the same type, grade, th
32、ickness range and composition or lay-up. The method of sampling and the number of panels required is given in EN 1058. Afull cross-sectional area, equal to bt, in square millimetres; bmeasured width of test piece, in millimetres; Emodulus of elasticity, in newtons per square millimetre; EAdirect sti
33、ffness, in newtons; EIbending stiffness, in newtons times square millimetres; Fload, in newtons; fstrength, in newtons per square millimetre; Gshear modulus of rigidity, in newtons per square millimetre; I second moment of area, equal to bt3/12, in millimetres to the fourth power; llength of test pi
34、ece, in millimetres; l1gauge length, in millimetres; l2distance between an inner load point and the nearest support, in millimetres; Mmoment, in newton millimetres; tmeasured thickness of test piece, in millimetres; t1measured thickness of panel being tested, in millimetres; udeflection or deformati
35、on, in millimetres; Wsection modulus, equal to bt2/6, in cubic millimetres. ccompression; mbending; max. maximum; ppanel shear; rplanar shear; ttension. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 789:1995 4 BSI 07-1999 5.2 Sampling o
36、f specimens The specimens for each type of test in each direction shall not be from the same position in different panels of the same sample and shall not number more than one from each panel. For compression test pieces, see Annex A (normative). The position of the specimens within the panels shall
37、 be selected to ensure an unbiased sample. NOTEAn example of a cutting schedule based on a sample of four panels, each with a minimum area of 1 200 mm 2 400 mm, is given in Figure 1. 6 Preparation of test pieces 6.1 Conditioning All test pieces shall be conditioned to constant mass in an atmosphere
38、of relative humidity (65 5) % and temperature (20 2) C. The constant mass is considered to have been reached when the results of two successive weighing operations, carried out at an interval of 24 h do not differ by more than 0,1 % of the mass of the test piece. If the conditions of testing are not
39、 the same as those in the conditioning chamber, tests shall be undertaken immediately after the test pieces have been removed from the conditioning chamber. NOTEThe test methods specified in this standard may also be used in other testing climates. 6.2 Dimensions of test pieces 6.2.1 Method of measu
40、rement The dimensions shall be determined in accordance with EN 325. 6.2.2 Measurements to be taken The thickness of the test pieces shall be measured at four points, two on each edge 80 mm from mid-length, but 25 mm in the case of compression test pieces, and the average thickness t recorded. The w
41、idth of the test pieces shall be measured at two points, generally 80 mm from mid-length, but 25 mm in the case of compression test pieces, and the average width b recorded. NOTEIf the thicknesses of individual plies or layers in plywood or composite panels are required, then each should be measured
42、 to the nearest 0,1 mm at the four edges of the test piece, and averaged. 6.3 Moisture content 6.3.1 Method of measurement The moisture content shall be determined in accordance with EN 322. 6.3.2 Measurements to be taken The moisture content shall be determined from at least one test piece per pane
43、l and measured at the time of testing. 6.4 Density 6.4.1 Method of measurement The density shall be determined in accordance with EN 323. 6.4.2 Measurements to be taken The density shall be determined from at least one test piece per panel and measured at the time of testing. 7 Bending properties 7.
44、1 Test piece The test piece shall be rectangular in cross-section. The depth of the test piece shall be equal to the thickness of the panel and the width shall be (300 5) mm, but see also 7.3 NOTE. The length of the test piece will depend on the nominal thickness of the panel, see Figure 2. 7.2 Load
45、ing equipment The loading equipment shall be capable of measuring the load to an accuracy of 1 %. NOTESince the test piece may twist under load, the loading equipment should be appropriately chosen. 7.3 Loading method The application of the loads shall be as shown in Figure 2 with the load and react
46、ion forces applied by rollers of (30 1) mm diameter. The distance between the load points and the supports shall be 16 times the nominal thickness, but not more than 400 mm and not less than 240 mm with an accuracy of 1 mm. NOTELarge deflections may occur when test pieces with small bending stiffnes
47、s are tested to failure thus alternative test arrangements may be required. In general the test configuration described in this section is suitable for a test piece with a thickness greater than 9 mm (corresponding to a bending stiffness per unit width of about 300 kN mm2/mm). Smaller thicknesses ma
48、y be tested by using smaller diameter rollers and proportionally reducing the distances between them. 7.4 Test procedure 7.4.1 Rate of application of load Load F shall be applied at a continuous rate of loading adjusted so that the maximum load is reached within (300 120) s, and with a mean value of
49、 about 300 s for a sample. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 789:1995 BSI 07-19995 Figure 1 Example of a cutting schedule Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 07 06:06:04 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 789:1995 6 BSI 07-1999 7.4.2 Measurement of length and deformation The lengths l1 and l2, see Figure 2, shall be measured to the nearest 1 mm. The deflection of the test piece shall be measured
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