1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 12369-2:2011Wood-based panels Characteristic values forstructural designPart 2: PlywoodBS EN 12369-2:2011 BRITISH STANDARDNational forewordThis British Standard is the UK i
2、mplementation of EN 12369-2:2011.It supersedes BS EN 12369-2:2004 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee B/541, Wood based panels.A list of organizations represented on this committee can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
3、does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 67069 5ICS 79.060.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority
4、of theStandards Policy and Strategy Committee on 31 July 2011.Amendments issued since publicationDate Text affectedBS EN 12369-2:2011EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12369-2 June 2011 ICS 79.060.10 Supersedes EN 12369-2:2004English Version Wood-based panels - Characteristic value
5、s for structural design - Part 2: Plywood Panneaux base de bois - Valeurs caractristiques pour la conception des structures - Partie 2: Contreplaqu Holzwerkstoffe - Charakteristische Werte fr die Berechnung und Bemessung von Holzbauwerken - Teil 2: Sperrholz This European Standard was approved by CE
6、N on 11 May 2011. 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 ma
7、y 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
8、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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Lu
9、xembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All r
10、ights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12369-2:2011: EBS EN 12369-2:2011EN 12369-2:2011 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Terms and definitions .54 Symbols 64.1 Main symbols .64.2 Subscripts 65 Genera
11、l 76 Characteristic values for plywood .76.1 Introduction 76.2 Bending, tension and compression .86.2.1 General 86.2.2 Strength 86.2.3 Modulus of elasticity 106.3 Shear properties . 106.4 Characteristic density 11Annex A (informative) Format for the presentation of characteristic values . 12Annex B
12、(informative) Information about the conversion factors . 14B.1 Tension Compression . 14B.1.1 General . 14B.1.2 Strength . 14B.1.3 Modulus of elasticity 14B.2 Shear properties . 15Bibliography . 17BS EN 12369-2:2011EN 12369-2:2011 (E) 3 Foreword This document (EN 12369-2:2011) has been prepared by Te
13、chnical 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 December 2011, and conflicting national standards shall b
14、e withdrawn at the latest by December 2011. 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 EN 12369-2:2004.
15、This standard is intended to be used in conjunction with EN 1995-1-1:2004. Compared to EN 12369-2:2004, the following changes have been made: a) The scope has been limited; b) Where no values were available, this document provides, for tension and compression, strength and stiffness values derived f
16、rom bending classes in each direction and taking the surface appearance class into account; c) This document gives more relevant values for shear properties in relation to the density of the wood species in the panel; d) The range of density, from 350 kg/m3to 750 kg/m3, corresponds to data used to d
17、etermine the correlation between these shear properties and density; e) The characteristic value of the density is determined by using the results of Factory Production Control (FPC). This European Standard is one of a series specifying characteristic values of wood-based panels for structural desig
18、n. The other parts of this series are listed in the Bibliography. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Es
19、tonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 12369-2:2011EN 12369-2:2011 (E) 4 1 Scope This European Standa
20、rd provides information on the characteristic values for use in designing structures incorporating wood-based panels. The characteristic values given in this standard are to be used in accordance with EN 1995-1-1. When utilizing the classification system for derivation of plywood characteristic valu
21、es, this European Standard can only be applied with reference to EN 636. This European Standard includes the characteristic values of the mechanical properties for plywood complying with EN 636 in bending, tension, compression, panel shear and planar shear. EN 636 classifies bending properties into
22、two sets of classes, one for stiffness and another for strength. Stiffness and strength in tension and compression are related to the same properties in bending. For shear properties, fixed values determined by correlation to density are provided. Where optimised values are needed, the characteristi
23、c values are determined directly by testing in accordance with EN 789 and EN 1058 or by combination of testing according to the latter two standards and calculation according to prEN 14272. This European Standard applies to panels complying with the three following conditions: 5 layers or more and 6
24、 mm overall thickness and more; the ratio of the cumulative thickness of veneers in alternate directions does not exceed 2,5; wood species with a mean density greater than 350 kg/m3and not exceeding 750 kg/m3. 2 Normative references The following referenced documents are indispensable for the applic
25、ation 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 310, Wood-based panels Determination of modulus of elasticity in bending and of bending strength EN 323, Wood-bas
26、ed panels Determination of density EN 326-2, Wood-based panels Sampling, cutting and inspection Part 2: Initial type testing and factory production control EN 635-2, Plywood Classification by surface appearance Part 2: Hardwood EN 635-3, Plywood Classification by surface appearance Part 3: Softwood
27、EN 636:2003, Plywood Specifications EN 1995-1-1:2004, Eurocode 5: Design of timber structures Part 1-1: General Common rules and rules for buildings ISO 3131, Wood Determination of density for physical and mechanical tests BS EN 12369-2:2011EN 12369-2:2011 (E) 5 3 Terms and definitions For the purpo
28、ses of this document, the following terms and definitions apply. 3.1 characteristic value value of a material property relating to limit state design, for use in the design of timber structures, elements, assemblies and component in accordance with EN 1995-1-1 NOTE 1 As defined in EN 1995-1-1, this
29、value corresponds to a specified percentile of the assumed distribution of the property under consideration. NOTE 2 For plywood determined as stipulated in this document. 3.2 service class NOTE Three service classes are defined in EN 1995-1-1. 3.2.1 service class 1 conditions of exposure resulting i
30、n moisture content in the materials corresponding to a temperature of 20 C and the relative humidity of the surrounding air exceeding 65 % for only a few weeks per year NOTE In these conditions the moisture content of coniferous plywood can be expected not to exceed 12 %. 3.2.2 service class 2 condi
31、tions of exposure resulting in moisture content in the materials corresponding to a temperature of 20 C and the relative humidity of the surrounding air exceeding 85 % for only a few weeks per year NOTE In these conditions the moisture content of coniferous plywood can be expected not to exceed 18 %
32、. 3.2.3 service class 3 conditions of exposure resulting in higher moisture content in the materials than in service class 2 NOTE In these conditions the moisture content of coniferous plywood can be expected to exceed 18 %. 3.3 load duration class class characterized by the effect of a constant loa
33、d acting for a certain period of time in the life of the structure NOTE 1 For a variable action, the appropriate class is determined on the basis of an estimate of the interaction between the typical variation of the load with time and the rheological properties of the materials. NOTE 2 For strength
34、 and stiffness calculations, actions are assigned to one of the load-duration classes given in Table 1, derived from EN 1995-1-1. BS EN 12369-2:2011EN 12369-2:2011 (E) 6 Table 1 Load duration classes Load duration class Order of accumulated duration of characteristic load Examples of loading Permane
35、nt More than 10 years Self weight Long-term 6 months to 10 years Storage Medium-term 1 week to 6 months Imposed load Short-term Less than 1 week Snow a and wind Instantaneous Accidental load aIn areas which have a heavy snow load for a prolonged period of time, part of the load should be regarded as
36、 medium-term 3.4 lay-up thickness and arrangement of the plies 3.5 composition factors compounding the lay-up plus the combination of wood species 4 Symbols 4.1 Main symbols E Modulus of elasticity (defined as stiffness in EN 1995-1-1:2004), (N/mm2) f Strength (N/mm2) G Modulus of rigidity (N/mm2) k
37、 Retention factor in strength (kmod) or stiffness (kdef) after a period of time relative to initial values. Values are included in EN 1995-1-1 Density of a wood species or of plywood (kg/m3) 0 In the direction of the grain of the outer layer of plywood 90 Perpendicular to the grain of the outer laye
38、r of plywood 4.2 Subscripts c Compression k or 05 Characteristic (5thpercentile) m Bending r Planar shear t Tension BS EN 12369-2:2011EN 12369-2:2011 (E) 7 v Panel shear w Wood species p Panel mean or 50 Mean (50thpercentile) mod related to modification factor for strength def related to modificatio
39、n factor for deflection 5 General In this standard the 5thpercentile defines the characteristic value for: strength; density; modulus of elasticity where buckling, as an example, may be expected in service. Otherwise the 50thpercentile defines the characteristic value of the modulus of elasticity. T
40、he characteristic value is derived in panels with moisture content as determined by a temperature of 20 C and a relative humidity of 65 %. The characteristic value of a property is to be used in design according to EN 1995-1-1. Where panels are structurally used under service class 1, 2 and 3 condit
41、ions, performance values inferred by the classification and listed in Table 2 and 3 shall be modified according to the service class and the duration of load (kmod, kdef). Manufacturers utilising the EN 636 classification system for determination of characteristic values may present these values in
42、a format similar to that in Annex A. The characteristic values shall be supported by the following information: product description; product specifications; service class or classes in which the panel can be used; details of the veneer species and grade, and of the composition; density of the panel.
43、 6 Characteristic values for plywood 6.1 Introduction Characteristic values for plywood can be determined by one of two distinct methods as described in Clause 1. The following tables in this clause provide the characteristic values for plywood based on the EN 636 Classification System. BS EN 12369-
44、2:2011EN 12369-2:2011 (E) 8 The class values given in these tables shall be modified appropriately for service class and load duration in accordance with the requirements of EN 1995-1-1. NOTE A data analysis has provided a conservative property relationship: - to bending for tension and compression
45、values and; - to density for shear values. See Annex B for more information on this relationship. 6.2 Bending, tension and compression 6.2.1 General Testing according to EN 310 and application of the procedure in EN 326-2 for internal control enables the classification of the panels according to the
46、ir composition and performances. Characteristic values are provided for bending strength (see Table 2) and bending stiffness (see Table 3) for the classes as defined by the EN 636 Classification System. Tables 1 and 2 in EN 636:2003 give the current threshold performance levels required to be achiev
47、ed for the purpose of classification. Although classification for strength and stiffness are independent of each other, the characteristic values for tension and compression in both cases are derived from bending strength. The surface appearance class, as defined in EN 635-2 and EN 635-3 shall be ta
48、ken into account both for modulus and strength. Declared characteristic values shall also make reference to these surface appearance classes. 6.2.2 Strength Class characteristic values for strength in bending, tension and compression, based on class limits as defined in EN 636 are listed in Table 2.
49、 BS EN 12369-2:2011EN 12369-2:2011 (E) 9 Table 2 Class characteristic values for strength in bending, tension and compression ClassaCharacteristic strength values (N/mm2or MPa) Surface grain direction a0 and 900 90 bending Tension and compression fm,05ft-c,05 F3 3 1,2 1,5F5 5 2 2,5F10 10 4 5 F15 15 6 7,5 F20 20 8 10F25 25 10 12,5F30 30 12 15 F40 40 16 20F50 50 20 25F60 60 24 30 F70 70 28 35F80 80 32 40aClass is to be identified for both parallel to grain (0) and perpend
