1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 1156:2013Wood-based panels Determination of duration ofload and creep factorsBS EN 1156:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation
2、 of EN 1156:2013. Itsupersedes DD ENV 1156:1999 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee B/541, Wood based panels.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport t
3、o include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 73753 4ICS 79.060.01Compliance with a British Standard cannot confer immunity fromlegal obligations.This
4、 British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 April 2013.Amendments issued since publicationDate T e x t a f f e c t e dBS EN 1156:2013EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 1156 April 2013 ICS 79.060.01 Supersedes ENV 1156:1998
5、English Version Wood-based panels - Determination of duration of load and creep factors Panneaux base de bois - Dtermination des facteurs de dure de charge et de fluage Holzwerkstoffe - Bestimmung von Zeitstandfestigkeit und Kriechzahl This European Standard was approved by CEN on 1 March 2013. CEN
6、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 appli
7、cation 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 Man
8、agement 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, Latv
9、ia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-100
10、0 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1156:2013: EBS EN 1156:2013EN 1156:2013 (E) 2 Contents Page Foreword . 3 1 Scope 4 2 Normative references . 4 3 Principle 4 4 Apparatus . 4 5 Sampling of panels and pr
11、eparation of test pieces 7 5.1 Sampling and cutting . 7 5.2 Dimensions of test pieces . 7 5.3 Conditioning . 7 6 Procedure . 8 6.1 Measurement of dimensions . 8 6.2 Setting up the test rigs with test pieces 8 6.3 Determination of short-term bending strength . 8 6.4 Determination of the duration of l
12、oad and creep factors . 8 6.4.1 General testing required 8 6.4.2 Testing for duration of load . 9 6.4.3 Testing for creep 9 7 Expression of results . 10 7.1 Duration of load factor . 10 7.2 Creep factor 11 8 Test report 13 Annex A (informative) Provisional test method for medium-size test pieces . 1
13、4 A.1 General . 14 A.2 Principle 14 A.3 Apparatus . 14 A.4 Sampling of panels and the preparation of test pieces 15 A.5 Procedure . 15 A.6 Expression of results . 15 A.7 Test report 15 Bibliography 16 BS EN 1156:2013EN 1156:2013 (E) 3 Foreword This document (EN 1156:2013) has been prepared by Techni
14、cal Committee CEN/TC 112 “Wood-based panels”, the secretariat of which is held by DIN. 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 October 2013, and conflicting national standards shall be wit
15、hdrawn at the latest by October 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 supersedes ENV 1156:1998. Compared
16、 to ENV 1156:1998, the following significant technical modifications have been made: a) status changed from ENV to EN; b) accuracy of the deflection measurement changed from 0,001 mm to 0,01 mm. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
17、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
18、, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 1156:2013EN 1156:2013 (E) 4 1 Scope This European Standard specifies a method of determining in a constant climate both a duration of load factor and a creep factor for wood-based panels
19、 stressed in flatwise bending with and without a shear component. Details of an alternative but provisional method employing medium sized test pieces are given in Annex A; this method can also be used for test pieces loaded under varying climates. NOTE The duration of load factor is necessary to mod
20、ify the characteristic strength values obtained in short-term structural tests in order to derive long-term values. The creep factor obtained in the test is used to predict a long-term deflection from the initial elastic deflection. 2 Normative references The following documents, in whole or in part
21、, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 310, Wood-based panels Determination of modulus
22、of elasticity in bending and of bending strength EN 325, Wood-based panels Determination of dimensions of test pieces EN 326-1, Wood-based panels Sampling, cutting and inspection Part 1: Sampling and cutting of test pieces and expression of test results EN 1058, Wood-based panels Determination of ch
23、aracteristic 5 -percentile values and characteristic mean values EN 1995-1-1, Eurocode 5: Design of timber structures Part 1-1: General Common rules and rules for buildings 3 Principle Determination in a constant climate of the load duration factor (loss in strength with time under load) and the cre
24、ep factor (ratio of increase in deflection with time to the initial elastic deflection) in bending by applying and sustaining a constant moment over the central region of a test piece; both the time to failure, and the increase in deflection with time are measured. 4 Apparatus 4.1 Measuring instrume
25、nts as specified in EN 325. 4.2 A number of test rigs (see Figure 1), that have essentially the following components: 4.2.1 Two parallel cylindrical supports of a length exceeding the width of the test piece and of diameter d = (15 0,5) mm. The distance between the supports shall be adjustable, and
26、each support shall be capable of rotating in its frame. Two cylindrical loading rollers of the same length and diameter as the supports. These shall lie parallel to the supports, be capable of rotating, and be linked together with cross-arms of fixed length. BS EN 1156:2013EN 1156:2013 (E) 5 The dis
27、tance l1between the loading rollers shall be 150 mm, the distance between one support and the nearer loading roller shall be five times the nominal thickness t of the test piece. The horizontal and vertical components of the loading cradle shall be rigidly connected. NOTE 1 For boards with a low ben
28、ding stiffness large deflections can occur. In general, the test configuration described here is suitable for a test piece with a stiffness (EmI) greater than 9 000 kNmm2; test pieces with a lower stiffness can be tested by proportionately reducing the distances between the rollers (l1+2 l2) as well
29、 as the distance between the deflection measuring points. NOTE 2 The load can be applied to the cross-arms through some form of mechanical advantage. Dimensions in millimetres Key F dead-load l1= 150 t thickness l2= 5 t L = l1+10 t+60 d = 15 0,5 Figure 1 Test arrangement for applying load for static
30、 bending and creep tests with test piece in position 4.2.2 A suitable instrument for measuring the deflection of the test piece in the middle of the span which is graduated to allow a reading to 0,01 mm or better and which enables readings of the displacement at the centre of the upper surface of th
31、e test piece to be taken in relation to two points on the upper surface of the test piece each 60 mm from the transverse centre line (see Figure 2). This general method will measure creep in bending free of any influence of shear (method 1). BS EN 1156:2013EN 1156:2013 (E) 6 Dimensions in millimetre
32、s Key F dead-load Figure 2 Method 1 (general method) for the measurement of deflection Where it is desired to measure creep in bending both with and without a shear component a measuring system as illustrated in Figure 3 shall be used (method 2). Dimensions in millimetres Key F dead-load Figure 3 Me
33、thod 2 for the measurement of deflection with and without a shear component 4.3 An arrangement for testing the short-term bending strength with the same loading configuration to the creep test arrangement. 4.4 Weights (= dead load) for applying different constant loads (forces) on the test pieces. 4
34、.5 A controlled environment room capable of maintaining a fixed temperature to 1 C and a fixed relative humidity to 3 %. 4.6 Equipment for recording temperature and relative humidity. BS EN 1156:2013EN 1156:2013 (E) 7 5 Sampling of panels and preparation of test pieces 5.1 Sampling and cutting Panel
35、s shall be sampled from production sites in accordance with EN 1058. Where previous static bending tests have indicated that the differences between the means of strength or modulus of elasticity in the two directions of the panel, i.e. longitudinal and transverse, is equal to, or less than 15 %, th
36、en a single set of test pieces may be used, provided that these are orientated in the direction of the lower values of strength and elasticity. Where these tests have indicated differences greater than 15 % in strength or modulus in the two directions, then two sets of test pieces shall be used. How
37、ever, if the end-use direction of span is known, then it is only necessary to carry out tests in that direction. Where there is no available information on the relative strength and modulus in the longitudinal and transverse directions, then this shall be determined prior to the start of creep testi
38、ng. Test pieces from the two directions shall be removed and tested according to EN 310. For creep, and load-duration tests, each set of test pieces shall comprise 70 pairs of side-matched test pieces cut in a manner that ensures that all panels and test pieces are sampled as equally as possible. Th
39、is number of samples is based on the assumption that at low stress levels the material is behaving in a linear viscoelastic mode. However, if there is doubt about this assumption, then creep tests should be carried out at more than one stress level as recommended in 6.4.3, and this will necessitate
40、additional test pieces equivalent to an extra 10 for each additional stress level. Test pieces shall be free of visible strength-reducing characteristics. Test pieces containing visible strength-reducing characteristics and of a larger size may be tested according to the provisional test method give
41、n in Annex A. 5.2 Dimensions of test pieces The test pieces shall be rectangular, and of the following dimensions: The width shall be (50 0,5) mm. For test pieces having a stiffness (EmI) greater than 9 000 kNmm2the length L shall be 10 times the nominal thickness plus 210 mm, with a maximum length
42、of 1 200 mm. For test pieces having a stiffness (EmI) of 9 000 kNmm2or less, the length of test piece may be reduced according to NOTE 1 of 4.2.1. 5.3 Conditioning Before testing, the test pieces shall be conditioned to constant mass in an atmosphere corresponding to the most severe conditions in ea
43、ch of the service classes (SC) according to EN 1995-1-1 to which the appropriate characteristic values apply: these are 20 C/65 % relative humidity for SC1, 20 C/85 % relative humidity for SC2, and 20 C/95 % relative humidity for SC3 (for tolerances see 4.5). Constant mass is considered to be reache
44、d 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. BS EN 1156:2013EN 1156:2013 (E) 8 6 Procedure 6.1 Measurement of dimensions Measure the width and thickness of each test piece in accordance w
45、ith EN 325 at the following points: the thickness at the intersection of the diagonals; the width at the mid length. 6.2 Setting up the test rigs with test pieces Adjust the distance between the centre of the support rollers of both the static bending rig and the creep test arrangement to within 1 m
46、m of 150 mm plus 10 times the nominal thickness of the panel (see Figure 1). Measure the distance between the centres of the support rollers with apparatus graduated to allow a reading of 0,5 mm or better. Reference points for the subsequent measurement of deflection shall be added to the top surfac
47、e of each of the 10 creep test pieces; these will usually take the form of thumbtacks, or small glass or metal plates with the measuring contact point defined with a limit of error 0,01 mm or better. 6.3 Determination of short-term bending strength Place one of the side-matched test pieces flat on t
48、he supports of the static bending test arrangement, with its length axis at right angles to those of the supports (see Figure 1). Determine its short-term static bending strength, under the same climatic conditions in which it was conditioned, by applying a load at a constant rate of cross-head move
49、ment throughout the test. The rate of loading shall be adjusted so that the maximum load Fmaxis reached within (60 30) s. Record the ultimate load to an accuracy of 1 % and calculate the bending strength fmof the test piece from Formula (1): )2/(2maxmWlFf = (1) where l2is 5 t as shown in Figure 1 W is the section modulus equal to bt2/6, in cubic millimetres (t is the measured thickness of test piece, in millimetres; and b is the measured width of test piece, in millimetres). Repeat the test with the face of half of the test pieces (each
