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BS EN 408:2010+A1:2012 BS EN 408:2010 BSI Standards Publication Timber structures — Structural timber and glued laminated timber — Determination of some physical and mechanical properties NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW raising standards worldwide™ BS EN 408:2010+A1:2012 BRITISH STANDARD Text affected 30 September 2012 Implementation of CEN amendment A1:2012 EN 408:2010+A1 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM July 2012 ICS 91.080.20; 79.040; 79.060.99 English Version Timber structures - Structural timber and glued laminated timber - Determination of some physical and mechanical properties Structures en bois - Bois de structure et bois lamellé-collé Détermination de certaines propriétés physiques et mécaniques Holzbauwerke - Bauholz für tragende Zwecke und Brettschichtholz - Bestimmung einiger physikalischer und mechanischer Eigenschaften This European Standard was approved by CEN on 16 June 2012 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 national standards may be obtained on application to the CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels © 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 408:2010+A1:2012: E BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Contents Page Foreword Introduction 5 Scope Normative references Terms and definitions 6 Symbols and abbreviations 6 Determination of dimensions of test pieces .8 Determination of moisture content of test pieces 8 Determination of density of test pieces 8 Conditioning of test pieces 8 9.1 9.2 9.3 Determination of local modulus of elasticity in bending 9 Test piece .9 Procedure .9 Expression of results 10 10 10.1 10.2 10.3 Determination of global modulus of elasticity in bending 11 Test piece 11 Procedure 11 Expression of results 12 11 11.1 11.1.1 11.1.2 11.1.3 11.2 11.2.1 11.2.2 11.2.3 Determination of the shear modulus 13 Torsion method 13 Test piece 13 Procedure 13 Expression of results 16 Shear field test method 17 Test piece 17 Procedure 17 Expression of results 19 12 12.1 12.2 12.3 Determination of modulus of elasticity in tension parallel to the grain 19 Test piece 19 Procedure 19 Expression of results 20 13 13.1 13.2 13.3 Determination of tension strength parallel to the grain 20 Test piece 20 Procedure 21 Expression of results 21 14 14.1 14.2 14.3 Determination of modulus of elasticity in compression parallel to the grain 21 Test piece 21 Procedure 22 Expression of results 22 15 15.1 15.2 15.3 Determination of compression strength parallel to grain 22 Test piece 22 Procedure 22 Expression of results 23 16 16.1 Determination of tension and compression strengths perpendicular to the grain 23 Requirements for test pieces 23 BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) 16.1.1 16.1.2 16.2 16.3 16.3.1 16.3.2 Fabrication 23 Surface preparation 23 Procedure 24 Expression of results 27 Compression perpendicular to the grain 27 Tension perpendicular to the grain 27 17 17.1 17.2 17.3 17.3.1 17.3.2 Determination of modulus of elasticity perpendicular to the grain 27 Requirements for test pieces 27 Procedure 27 Expression of results 28 Compression perpendicular to the grain 28 Tension perpendicular to the grain 28 18 18.1 18.1.1 18.1.2 18.2 18.3 Determination of shear strength parallel to the grain 29 Requirements for test pieces 29 Fabrication 29 Surface preparation 29 Procedure 30 Expression of results 31 19 19.1 19.2 19.3 Bending strength parallel to grain 32 Test piece 32 Procedure 32 Expression of results 33 20 20.1 20.2 20.3 20.4 Test report 34 General 34 Test piece 34 Test method 34 Test results 34 Annex A (informative) Example of compression perpendicular to grain test arrangement 35 Annex B (informative) Example of tension perpendicular to grain test arrangement with rigid fixings 37 Bibliography 38 BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Foreword This document (EN 408:2010+A1:2012) has been prepared by Technical Committee CEN/TC 124 “Timber structures”, the secretariat of which is held by AFNOR 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 January 2013, and conflicting national standards shall be withdrawn at the latest by January 2013 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights This document includes Amendment approved by CEN on 16 June 2012 The start and finish of text introduced or altered by amendment is indicated in the text by tags !" This document supersedes !EN 408:2010." In this revised standard a new test is added for the determination of the shear modulus According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) Introduction This 2010 revision replaces the test for the determination of the shear strength parallel to grain The revised edition of 2003 added a global bending modulus of elasticity, whilst renaming the existing test as the local modulus of elasticity It also includes the methods for determination of shear strength and mechanical properties perpendicular to the grain, previously given in EN 1193, which has now been withdrawn The values obtained in any determination of the properties of timber depend upon the test methods used It is therefore desirable that these methods be standardized so that results from different test centres can be correlated Moreover, with the adoption of limit state design and with the development of both visual and machine stress grading, attention will be increasingly centred on the determination and monitoring of the strength properties and variability of timber in structural sizes Again, this can be more effectively undertaken if the basic data are defined and obtained under the same conditions This European Standard, which is based originally on ISO 8375, specifies laboratory methods for the determination of some physical and mechanical properties of timber in structural sizes The methods are not intended for the grading of timber or for quality control For the determination of shear modulus, alternative methods have been specified The choice of which to use will depend upon the objective of the investigation and, to some extent, on the equipment available Following testing to this standard it is intended that the determination of characteristic values will normally be obtained according to procedures specified in other European Standards Attention is drawn to the advantages that may be gained, often with little extra effort, in extending the usefulness of test results by recording additional information on the growth characteristics of the pieces that are tested, particularly at the fracture sections Generally, such additional information should include gradedetermining features such as knots, slope of grain, rate of growth, wane, etc., on which visual grading rules are based, and strength indicating parameters such as localized modulus of elasticity, on which some machine stress grading is based BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Scope This European Standard specifies test methods for determining the following properties of structural timber and glued laminated timber: modulus of elasticity in bending; shear modulus; bending strength; modulus of elasticity in tension parallel to the grain; tension strength parallel to the grain; modulus of elasticity in compression parallel to the grain; compression strength parallel to the grain; modulus of elasticity in tension perpendicular to the grain; tension strength perpendicular to the grain; modulus of elasticity in compression perpendicular to the grain; compression strength perpendicular to the grain and shear strength In addition, the determination of dimensions, moisture content, and density of test pieces are specified The methods apply to rectangular and circular shapes (of substantially constant cross section) of solid unjointed timber or finger-jointed timber and glued laminated timber unless stated otherwise Normative references The following 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 384:2010, Structural timber — Determination of characteristic values of mechanical properties and density" EN 13183-1, Moisture content of a piece of sawn timber ― Part 1: Determination by oven dry method Terms and definitions Not applicable Symbols and abbreviations A cross-sectional area, in square millimetres; a distance between a loading position and the nearest support in a bending test, in millimetres; b width of cross section in a bending test, or the smaller dimension of the cross section, in millimetres; Ec,0 modulus of elasticity in compression parallel to the grain, in newtons per square millimetre; Ec,90 modulus of elasticity in compression perpendicular to the grain, in newtons per square millimetre; Em,g global modulus of elasticity in bending, in newtons per square millimetre; Em,l local modulus of elasticity in bending, in newtons per square millimetre; Et,0 modulus of elasticity in tension parallel to the grain, in newtons per square millimetre; Et,90 modulus of elasticity in tension perpendicular to the grain, in newtons per square millimetre; F load, in newtons; Fc,90 compressive load perpendicular to the grain, in newtons; Fc,90,max maximum compressive load perpendicular to the grain, in newtons; Fc,90,max,est estimated maximum compressive load perpendicular to the grain, in newtons; BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) Fmax maximum load, in newtons; Fmax,est estimated maximum load, in newtons; Ft,90 tensile load perpendicular to the grain, in newtons; Ft,90,max maximum tensile load perpendicular to the grain, in newtons; G shear modulus, in newtons per square millimetre; S first moment of area, in millimetres to the third power; fc,0 compressive strength parallel to the grain, in newtons per square millimetre; fc,90 compressive strength perpendicular to the grain, in newtons per square millimetre; fm bending strength, in newtons per square millimetre; ft,0 tensile strength parallel to the grain, in newtons per square millimetre; ft,90 tensile strength perpendicular to the grain, in newtons per square millimetre; fv shear strength parallel to the grain, in newtons per square millimetre; fv,k characteristic shear strength parallel to the grain, in newtons per square millimetre; G shear modulus, in newtons per square millimetre; Gtor,t shear modulus in torsion, in newtons per square millimetre; Gtor,s shear modulus in shear field, in newtons per square millimetre; h depth of cross section in a bending test, or the larger dimension of the cross section, or the test piece height in perpendicular to grain and shear tests, in millimetres; h0 gauge length, in millimetres; I second moment of area, in millimetres to the fourth power; K, k coefficients; kG coefficient for shear modulus; ktor torque stiffness, in newton metres per radian; ks shear stiffness; l span in bending, or length of test piece between the testing machine grips in compression and tension, in millimetres; l1 gauge length for the determination of modulus of elasticity or shear modulus, in millimetres; l2 distance between the supports and gauge length in torsion, in millimetres; t plate thickness, in millimetres; Tr torque, in newton millimetres; BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Vs shear force, in newtons; W section modulus, in millimetres to the third power; w deformation or displacement, in millimetres; ϕ rotation, in radians; χ, η shape factors Suffixes 1, refer to loads or deformations or pieces at particular points of a test and are referred to as necessary in the text Determination of dimensions of test pieces The dimensions of the test piece shall be measured to an accuracy of % All measurements shall be made when the test pieces are conditioned as specified in Clause If the width or thickness varies within a test piece, these dimensions should be recorded as the average of three separate measurements taken at different positions on the length of each piece The measurements shall not be taken closer than 150 mm to the ends Specimens for perpendicular to grain tests shall be planed Determination of moisture content of test pieces The moisture content of the test piece shall be determined in accordance with EN 13183-1 on a section taken from the test piece For structural timber the section shall be of full cross section, free from knots and resin pockets For perpendicular to grain test specimens the moisture content shall be determined from the whole specimen In strength tests for bending and tension parallel to grain and compression parallel to grain, the section shall be cut as close as possible to the fracture Determination of density of test pieces The density of the whole cross section of the test piece shall be determined on a section taken from the test piece For structural timber the section shall be of full cross section, free from knots and resin pockets In strength tests, the section shall be cut as close as possible to the fracture For perpendicular to grain test specimens the density of the test pieces shall be determined prior to test after conditioning from the measurements of mass and volume of the whole test piece Conditioning of test pieces All tests shall be carried out on pieces, which are conditioned at the standard environment of (20 ± 2) °C and (65 ± 5) % relative humidity A test piece is conditioned when it attains constant mass Constant mass is considered to be attained when the results of two successive weightings, carried out at an interval of h, not differ by more than 0,1 % of the mass of the test piece Where the timber to be tested is not readily conditioned to the above standard environment (e.g for hardwoods with high densities) that fact shall be reported BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Figure 13 — Test principle The loading equipment used shall be capable of measuring the load to an accuracy of % of the load applied to the test piece or, for loads less than 10 % of the maximum load, with an accuracy of 0,1% of the maximum load The test piece shall be loaded concentrically NOTE This can be achieved using spherically seated loading-heads (see also Annexes A and B) In the case of the compression test, after an initial load has been applied, the loading-heads shall be locked to prevent rotation or angular movement during the test NOTE Suitable devices are shown in Annex A In the case of either a tension test or a compression test the longitudinal axis of the test piece shall be aligned with the axis of the machine and fixed in such a way that no initial stresses in the test piece are introduced, except those due to the weight of the test piece and the equipment In the case of tension tests on solid timber the test piece shall have pinned ends, with the axis of the pin parallel to the grain direction of the test piece 26 BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) The load F shall be applied at a constant rate of cross head movement throughout the test The rate of loading shall be adjusted so that the maximum load Fc,90,max,est or Ft,90,max is reached within (300 ± 120) s NOTE This rate should be determined from the results of preliminary tests The objective is that the time to reach Fmax for each test piece is 300 s NOTE The relationship between Fc,90,max,est and Fc,90,max is discussed in 17.3.1 16.3 Expression of results 16.3.1 Compression perpendicular to the grain The compressive strength fc,90 shall be determined from the equation: f c,90 = Fc,90,max bl The compressive strength shall be calculated to an accuracy of % The method for determining Fc,90,max is given in 17.3.1 The symbols are as given in Clause 16.3.2 Tension perpendicular to the grain The tensile strength ft,90 shall be determined from the equation: f t,90 = Ft ,90, max bl (13) The tensile strength shall be calculated to an accuracy of % The symbols are as given in Clause The result of a test shall be disregarded where failure occurs on the system used to connect the test piece to the testing machine (e.g in the glue line between the steel plates and the timber of the test piece) If the failure occurs partly in the glued area of the test piece/steel plate interface, the result is valid only if this area is less than 20 % of the area of failure 17 Determination of modulus of elasticity perpendicular to the grain 17.1 Requirements for test pieces The shape and dimensions of the test pieces shall comply with Table 17.2 Procedure The test pieces shall be mounted in the loading equipment as specified in 16.2, and the loading procedure described in 16.2 shall be followed Two extensometers shall be used, and shall be positioned to minimize the effects of distortion The extensometers shall measure the deformations which shall be determined to an accuracy of % The deformation in the load direction refers to the centre of the loaded section and is calculated on the basis of measurements on two opposite sides of the test piece The data from each extensometer shall be recorded separately 27 BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) 17.3 Expression of results 17.3.1 Compression perpendicular to the grain The modulus of elasticity Ec,90 shall be calculated from the equation: E c,90 = ( F40 − F10 )h0 ( w40 − w10 )bl (14) where F40 – F10 is an increment of load on the straight line portion of the load-deformation curve, in newtons F10 shall be 10 % and F40 shall be 40 % of Fc,90,max,est; w40 – w10 is the increment of deformation corresponding to F40 – F10 , in millimetres The other symbols are as given in Clause The modulus of elasticity shall be calculated to an accuracy of % Figure 14 — Load-deformation diagram (compression) The determination of Fc,90,max may be carried out using the iterative process as follows: Estimate a value for the load Fc,90,max Using the test results, plot the load/deformation curve in the form shown in Figure 14 Calculate 0,1 Fc,90,max and 0,4 Fc,90,max and determine where these two values intersect the load/deformation curve Through these two points draw the straight line as shown in Figure 14 Parallel to line 1, draw line having its origin at load F = and at a distance from it equivalent to a deformation of 0,01 h0 as shown in Figure 14 Where line intersects the curve of the test results is Fc,90,max If the value of Fc,90,max as determined is within % of Fc,90,max,est then that value may be used to determine the compressive strength; otherwise, repeat the procedure until a value of Fc,90,max within that tolerance is obtained 17.3.2 Tension perpendicular to the grain The modulus of elasticity Et,90 shall be calculated from the equation: 28 BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) E t,90 = ( F40 − F10 )h0 ( w40 − w10 )bl (15) where F40 – F10 is an increment of load on the straight line portion of the load-deformation curve, in newtons F10 shall be 10 % and F40 shall be 40 % of Ft,90,max,est; w40 – w10 is the increment of deformation corresponding to F40 – F10 , in millimetres The other symbols are as given in Clause The modulus of elasticity shall be calculated to an accuracy of % 18 Determination of shear strength parallel to the grain 18.1 Requirements for test pieces 18.1.1 Fabrication The test piece shall be glued to steel plates The steel plates shall be tapered as shown in Figure 15 NOTE A suitable adhesive for fixing the steel plates to the timber test piece is a two-part epoxy Immediately prior to gluing, the surfaces to be joined should be prepared by planing the timber test piece surfaces and sandblasting the steel plates 18.1.2 Surface preparation All surfaces shall be accurately prepared to ensure that adjacent surfaces are perpendicular and opposite surfaces are parallel to each other This preparation shall be carried out after conditioning The test pieces shall satisfy the requirements shown in Figure 15 The values of the dimensions shall be as follows: l = (300 ± 2) mm; b = (32 ± 1) mm; h = (55 ± 1) mm The steel plate thickness shall be (10 ± 1) mm NOTE Consideration needs to be given to thicker plates for stronger species and hardwoods NOTE Variations in these dimensions are permissible within the stated tolerances, to achieve the object of an angle of 14° in the test 29 BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Dimensions in millimetres Key grain direction steel plate timber test piece Figure 15 — Timber test piece shown glued to steel plates 18.2 Procedure The test piece shall be mounted in a test machine as shown in Figure 16 The test piece shall be aligned such that continuous contact is maintained where the line loads F are applied The angle between the load direction and the longitudinal axis of the test piece shall be 14° 30 BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) Key grain direction steel plate timber test piece Figure 16 — Loading arrangement The loading equipment used shall be capable of measuring the load to an accuracy of % of the load applied to the test piece or, for loads less than 10 % of the maximum load, with an accuracy of 0,1% of the maximum load If the failure occurs partly in the glued area of the test piece/steel plate interface, the result is valid only if this area is less than 20 % of the area of failure Load F shall be applied at a constant rate of loading-head movement so adjusted that the load Fmax is reached within (300 ± 120) s NOTE This rate should be determined from the results of preliminary tests The objective is that the time to reach Fmax for each test piece is 300 s Single test pieces diverging more than 120 s from the target of 300 s shall be reported The time to failure shall be recorded and its average reported 18.3 Expression of results The shear strength fv shall be determined from the equation: 31 BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) fv = Fmax cos 14° lb (16) and shall be calculated to an accuracy of % The symbols are as given in Clause 19 Bending strength parallel to grain 19.1 Test piece For the determination of the bending strength of the timber the test piece shall have a minimum length of 19 times the depth of the section Where this is not possible, the span of the beam shall be reported For the determination of the bending strength of the finger jointed timber the test piece shall have a minimum length of !19" times the depth of the section Where this is not possible, the span of the beam shall be reported 19.2 Procedure For the determination of the bending strength of the timber the test piece shall be symmetrically loaded in bending at two points over a span of 18 times the depth as shown in Figure 17 For the determination of the bending strength of the finger jointed timber the test piece shall be symmetrically loaded in bending at two points over a span of !18" times the depth as shown in Figure 18 with the finger joint at mid span If the test piece and equipment not permit these conditions to be achieved exactly, the distance between the load points and the supports may be changed by an amount not greater than 1,5 times the piece depth, and the span and test piece length may be changed by an amount not greater than three times the piece depth, while maintaining the symmetry of the test The test piece shall be simply supported !NOTE 1" Small steel plates of length not greater than one-half of the depth of the test piece may be inserted between the piece and the loading heads or supports to minimize local indentation Lateral restraint shall be provided as necessary to prevent buckling This restraint shall permit the piece to deflect without significant frictional resistance !Load shall be applied at a constant loading-head movement so adjusted that maximum load is reached within (300 ± 120) s NOTE This rate will be determined from the results of preliminary tests The objective is that the time to reach Fmax for each test piece is 300 s." Failures that originate from other types than bending shall be reported The maximum load (Fmax) of the bending test shall be recorded 32 BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) Figure 17 — Test arrangement for measuring bending strength Figure 18 — Test arrangement for measuring the bending strength of finger joints The loading equipment used shall be capable of measuring the load to an accuracy of % of the load applied to the test piece or, for loads less than 10 % of the applied maximum load, with an accuracy of 0,1 % of the maximum applied load 19.3 Expression of results The bending strength is determined by: Fa fm = bh (17) The symbols are as given in Clause The bending strength shall be calculated to an accuracy of % The mode of fracture and the growth characteristics at the fracture section of each test piece shall be recorded 33 BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) 20 Test report 20.1 General The test report shall include details of the test piece, the test method used and the test results 20.2 Test piece The following information shall be given: a) description of the test piece, a specification and quality of material: species or type, grade, density, deviations from specifications, strength reducing characteristics, size of defects; b) size of test piece or finger joint, the type of glue used if applicable and the orientation and the number of laminations where appropriate; c) country, region or mill of origin of the material sampled In addition, for glued laminated timber, the factory of origin; d) method of selection of test pieces; e) method of conditioning; f) any other information which may have influenced the test results, for example drying history 20.3 Test method The following information shall be given: a) reference to test methods used; b) temperature and relative humidity at the time of test; c) description of the load testing device, the test equipment and the measuring instruments used; d) any other information which may influence the use of the test results 20.4 Test results The following information for each test piece shall normally be given: a) moisture content of the test piece at time of test; b) actual dimensions; c) strength and/or stiffness values; d) location and shape of the cracks or other failure modes than intended; e) estimated percentage glued line and wood failure in the finger joint if applicable; f) time to reach the maximum load; g) any other information which may influence the use of the test results 34 BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) Annex A (informative) Example of compression perpendicular to grain test arrangement Figure A.1 shows an example of a compression perpendicular to grain test arrangement The load can be transferred to the test piece through steel plates To ensure uniform deformation from the beginning of the load application, a pair of steel wedges can be inserted between the steel plate and the pressure disc of the testing machine This enables the equalization of small deviations in parallelity The use of the devices shown in Figure A.2 will: facilitate the correct alignment of the test piece between the platens of the test machine; and facilitate full contact between the end surfaces of the test piece and the platens of the test machine; and following the initial loading, prevent any further rotation of the platens Figure A.1 — Compression test arrangement 35 BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Key test piece square plate with hemispherical knee joint adjustment and locking system Figure A.2 — Compression test locking device 36 BS EN 408:2010:+A1:2012 EN EN 408:2010+A1:2012 408:2010+A1:2012 (E) (E) Annex B (informative) Example of tension perpendicular to grain test arrangement with rigid fixings The load can be transferred to the test piece through steel plates glued to the test piece or by timber pieces For the glued on timber pieces the direction of the grain should be parallel the load direction A suitable adhesive to glue steel plates to timber is a two-component epoxy For timber to timber any appropriate adhesive will Using steel plates the interface surfaces should be prepared by sandblasting the steel and planing the wood just before the gluing Alternatively, to provide the load introduction not only steel plates but also other suitable load introduction methods can be applied provided no eccentricity with the symmetrical axis of the specimen occurs An example of the arrangement is shown in Figure B.1 for glued laminated test pieces Figure B.1 — Tension test arrangements and load introduction methods for a glued laminated test piece 37 BS EN 408:2010:+A1:2012 EN 408:2010+A1:2012 EN 408:2010+A1:2012 (E) (E) Bibliography [1] ISO 8375:2009, Timber structures — Glued laminated timber — Test methods for determination of physical and mechanical properties [2] Feldborg, T., Determination of some mechanical properties of timber in structural sizes, In Proceedings of the 1991 International Timber Engineering Conference, London 1991, Vol.2 p189-199 [3] Brandner, R., Gehri, E., Bogensperger, T., Schickhofer, G Determination of modulus of shear and elasticity of glued laminated timber and related examinations, Proceedings of CIB - 18 paper 40-12-2, Bled, August 2007 38 This page deliberately left blank British Standards Institution (BSI) BSI is the independent national body responsible for preparing British Standards and other standards-related publications, information and services It presents the UK view on standards in Europe and at the international level BSI is incorporated by Royal Charter British Standards and other standardisation products are published by BSI Standards Limited Revisions Information on standards British Standards and PASs are periodically updated by amendment or revision Users of British Standards and PASs should make sure that they possess the latest 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