1、BRITISH STANDARD BS EN 789:2004 Timber structures Test methods Determination of mechanical properties of wood based panels The European Standard EN 789:2004 has the status of a British Standard ICS 79.040 BS EN 789:2004 This British Standard was published under the authority of the Standards Policy
2、and Strategy Committee on 16 March 2005 BSI 16 March 2005 ISBN 0 580 45606 4 National foreword This British Standard is the official English language version of EN 789:2004. It supersedes BS EN 789:1996 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee
3、B/518, Timber structures, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the
4、 BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible f
5、or its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK in
6、terests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 32, an inside back cover and a back cover. The BSI copyright notice displayed in this
7、document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 789 October 2004 ICS 79.040 Supersedes EN 789:1995 English version Timber structures - Test methods - Determination of mechanical prop
8、erties 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 Holzwerkstoffen This European Standard was approved by CEN on 1 April 2004. CEN members are boun
9、d 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 national standards may be obtained on application to the Ce
10、ntral 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 notified to the Central Secretariat has the same status a
11、s the official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, S
12、pain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2004 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN nation
13、al Members. Ref. No. EN 789:2004: EEN 789:2004 (E) 2 C o n t e n t s page Foreword4 Introduction .5 1 Scope.6 2 Normative references 6 3 Terms and definitions6 4 Symbols and abbreviations 6 5 Sampling .7 5.1 Sampling of panels7 5.2 Sampling of specimens.7 6 Preparation of test pieces .9 6.1 Conditio
14、ning9 6.2 Dimensions of test pieces .9 6.2.1 Methods of measurement .9 6.2.2 Measurements to be taken .9 6.3 Moisture content9 6.3.1 Method of measurement.9 6.3.2 Measurements to be taken .9 6.4 Density9 6.4.1 Method of measurement.9 6.4.2 Measurements to be taken .9 7 Bending properties 10 7.1 Test
15、 piece10 7.2 Loading equipment10 7.3 Loading method10 7.4 Test procedure10 7.4.1 Rate of application of load 10 7.4.2 Measurement of length and deformation11 7.5 Expression of results.11 7.5.1 Modulus of elasticity and bending stiffness 11 7.5.2 Bending strength and moment capacity .12 8 Compression
16、 properties in the plane of the panel .12 8.1 Test piece12 8.2 Loading equipment12 8.3 Loading method13 8.4 Test Procedure13 8.4.1 Rate of application of load 13 8.4.2 Measurement of length and deformation13 8.5 Expression of results.14 8.5.1 Compression of modulus of elasticity and stiffness14 8.5.
17、2 Compression strength.14 9 Tension properties.14 9.1 Test piece14 9.2 Loading equipment15 9.3 Loading method15 9.4 Test procedure15 9.4.1 Rate of application of load 15 9.4.2 Measurement of length and deformation15 9.5 Expression of results16 9.5.1 Tension modulus of elasticity and stiffness 16 EN
18、789:2004 (E) 3 9.5.2 Tension strength. 16 10 Panel shear properties . 16 10.1 Test piece. 16 10.2 Loading equipment. 17 10.3 Measurement of deformation . 17 10.4 Loading method 17 10.5 Test procedure. 18 10.5.1 Rate of application of load . 18 10.5.2 Measurement of deformation. 18 10.5.3 Failure mod
19、e 18 10.6 Expression of results 18 10.6.1 Panel shear modulus of rigidity 18 10.6.2 Panel shear strength 18 11 Planar shear properties 19 11.1 Test piece. 19 11.2 Loading equipment. 19 11.3 Loading method 19 11.4 Test procedures 19 11.4.1 Rate of application of load . 19 11.4.2 Measurement of deform
20、ation. 19 11.5 Expression of results 20 11.5.1 Planar shear strength. 20 11.5.2 Planar shear modulus of rigidity. 20 12 Test report 21 12.1 General data. 21 12.2 Material data21 12.3 Data of individual test pieces 22 12.4 Data of physical properties. 22 12.5 Additional data 22 12.6 Sampling data. 22
21、 Annex A (normative) In-plane compression test pieces 23 Annex B (normative) Panel shear test pieces 26 Annex C (normative) Planar shear test pieces 28 Annex D (informative) Compression properties perpendicular to the plane of the panel (bearing) . 29 Bibliography 32 EN 789:2004 (E) 4 Foreword This
22、document (EN 789:2004) has been prepared by Technical Committee CEN/TC 124 “Timber Structures“, the secretariat of which is held by SFS. 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 April 2005,
23、 and conflicting national standards shall be withdrawn at the latest by April 2005. This document supersedes EN 789:1995. This document includes a Bibliography. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard; Austria, Belgium,
24、 Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 789:2004 (E) 5 Introduction The following
25、amendments have been made to EN 789:1995: - Certain descriptions of test methods and expressions of the test results have been improved. - Following further research, the panel and planar shear test methods have been revised and moved from the annexes to the main part of the document. - A method for
26、 compression perpendicular to the plane of the panel has been added, as Annex D. These changes are based on the results and experience of research carried out at a number of European laboratories. EN 789:2004 (E) 6 1 Scope This document specifies test methods for determining some mechanical properti
27、es of commercial wood-based panel products for use in load-bearing timber structures. These properties are intended for the calculation of characteristic values for use in obtaining material design values. For each type and grade of load-bearing panel product, as defined in the Harmonised Standard f
28、or wood-based panels (EN 13986), it is necessary to determine characteristic values of mechanical properties to enable it to be used for structural purposes. This document details the testing required to establish characteristic values. The tests need only be carried out once for each product, unles
29、s there is a reason to suspect a significant change has occurred in the properties of the product. NOTE For certain types and grades of panel, characteristic values are given in EN 12369 and these may be used for appropriate panels without further testing to this document. This document is not inten
30、ded to be used for quality control testing, for which smaller test pieces than specified herein, are adequate. Due to the limited experience in use, the test method for compression perpendicular to the plane of the panel (bearing) is included in Annex D (informative). 2 Normative references The foll
31、owing referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 322, Wood-based panels -Determination of moisture cont
32、ent EN 323, Wood-based panels - Determination of density EN 325, Wood-based panels - Determination of dimensions of test pieces EN 14358, Structural timber Calculation of characteristic 5-percentile value 3 Terms and definitions For the purposes of this document, the following terms and definitions
33、apply. 3.1 specimen piece of the panel from which a test piece will be fabricated 3.2 test piece specimen of aggregate of parts from a sample fabricated to the size and shape required for testing 4 Symbols and abbreviations A full cross-sectional area, equal to bt, in square millimetres; b measured
34、width of test piece, in millimetres; E modulus of elasticity, in newtons per square millimetre; F load, in newtons; f strength, in newtons per square millimetre; EN 789:2004 (E) 7 G shear modulus of rigidity, in newtons per square millimetre; I second moment of area, equal to bt 3 /12. In millimetre
35、s to the fourth power; l length of test piece, in millimetres; l 1gauge length, in millimetres; l 2distance between an inner load point and the nearest support, in millimetres; M moment, in newton millimetres; t measured thickness of test piece, in millimetres; t 1 measured thickness of panel being
36、tested, in millimetres; u deflection or deformation, in millimetres; W section modulus, equal to bt 2 /6, in cubic millimetres. Subscripts applied to loads, capacities, strengths, stiffness, and moduli of elasticity; c compression; m bending; max. maximum; v panel shear; r planar shear; t tension; p
37、erp perpendicular to the plane of the panel. 5 Sampling 5.1 Sampling of panels All panels in a sample shall be of the same type, grade, thickness range and composition or lay-up. The method of sampling and the number of panels required is given in EN 14358. 5.2 Sampling of specimens The specimens fo
38、r 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 in-plane compression test pieces, see Annex A (normative). The position of the specimens within the panels shall be selected to ens
39、ure an unbiased sample. NOTE 1 An example of a cutting schedule based on a sample of four panels, each with a minimum area of 1 200 mm x 2 400 mm, is given in Figure 1. NOTE 2 For quality control purposes, it may be necessary to establish correlations between the results from the test methods listed
40、 here and those used in the factory. If this is the case, consideration should be given to modifying the cutting plan to allow for the additional test pieces to be included on a “side-matched” basis. EN 789:2004 (E) 8 Dimensions in millimetres Figure 1 - Example of a cutting schedule Test Specimen n
41、umber Bending longitudinal 1 to 4 lateral 5 to 8 Tension longitudinal 9 to 12 lateral 13 to 16 Compression longitudinal 17 to 20 lateral 21 to 24 Panel shear longitudinal 25 to 28 lateral 29 to 32 Planar shear longitudinal 33 to 36 lateral 37 to 40 EN 789:2004 (E) 9 6 Preparation of test pieces 6.1
42、Conditioning All test pieces shall be conditioned to constant mass in an atmosphere 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
43、 more than 0,1% of the mass of the test piece. If the ambient conditions of testing are not the same as those in the conditioning chamber, tests shall be undertaken immediately after the test pieces have been removed from the conditioning chamber. NOTE The test methods specified in this document may
44、 also be used in other testing climates. 6.2 Dimensions of test pieces 6.2.1 Methods of measurement 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, b
45、ut 25 mm in the case of the in-plane compression test pieces, and the average thickness t recorded. The width of the test pieces shall be measured at two points, generally 80 mm from mid-length, but 25 mm in the case of the in-plane compression test pieces, and the average width b recorded. NOTE If
46、the thicknesses of individual plies or layers in plywood or composite panels are required, then each should be measured 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 wit
47、h EN 322. 6.3.2 Measurements to be taken The moisture content shall be determined from at least one test piece per panel 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
48、shall be determined from at least one test piece per panel and measured at the time of testing. EN 789:2004 (E) 10 7 Bending properties 7.1 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
49、 (300 5) mm, but see also the NOTE in 7.3. The length of the test piece will depend on the nominal thickness of the panel, see Figure 2. 7.2 Loading equipment The loading equipment shall be capable of measuring the load to an accuracy of 1%. NOTE Since 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 reaction forces applied by rollers of (30 1)
