1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 14272:2011Plywood Calculation methodfor some mechanical propertiesCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo re
2、production or networking permitted without license from IHS-,-,-BS EN 14272:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 14272:2011. Itsupersedes DDENV14272:2002 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommitt
3、ee 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 to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 201
4、2ISBN 978 0 580 69385 4ICS 79.060.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 January 2012.Amendments issued since publicationDate Text affectedCopyright
5、European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 14272:2011EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14272 December 2011 ICS 79.060.10 Supersedes ENV 14272:2002English Vers
6、ion Plywood - Calculation method for some mechanical properties Contreplaqu - Mthode de calcul pour certaines caractristiques mcaniques Sperrholz - Rechenverfahren fr einige mechanische Eigenschaften This European Standard was approved by CEN on 1 October 2011. CEN members are bound to comply with t
7、he 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 Manageme
8、nt 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
9、 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, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
10、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 rights of exploitation in any form and by any means reser
11、ved worldwide for CEN national Members. Ref. No. EN 14272:2011: ECopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 14272:2011EN 14272:2011 (E) 2 Contents Page Foreword 41 Sco
12、pe 52 Normative references 53 Principle 54 Terms and definitions .65 Symbols 65.1 Main symbols .65.2 Subscripts 76 Calculation method86.1 General 86.2 Properties relevant to the calculation methods .86.3 Wood species .86.4 Factors for plywood composition 87 Characteristic values for strength and sti
13、ffness in bending, tension and compression 117.1 General . 117.2 Bending 117.2.1 General . 117.2.2 Modulus of elasticity 117.2.3 Strength . 117.3 Tension and compression . 127.3.1 Stiffness and capacity of the layers in the cross section 127.3.2 Stiffness and capacity of the panel. 137.3.3 Property
14、of the panel (as if homogenized) . 137.4 Property values for layers 137.4.1 General . 137.4.2 Modulus of elasticity (, ; . 147.4.3 Resistance . 148 Shear properties . 158.1 Panel shear 158.1.1 Panel shear rigidity (Gv) . 158.1.2 Panel shear strength (fv) 168.2 Planar shear 168.2.1 General . 168.2.2
15、Planar shear rigidity (Gr) 168.2.3 Planar shear strength (fr) . 179 Ratio of strength upon modulus . 1710 Density . 1711 Conversion from strength and modulus of elasticity to capacity and stiffness 18Annex A (normative) Derivation for the veneer values (or basic values) . 19A.1 Scope . 19A.2 Princip
16、le . 19A.2.1 Option 1: Using plywood test results . 19A.2.2 Option 2: Using solid timber properties . 19A.3 Procedure for derivation of properties from testing plywood . 19A.3.1 General . 19A.3.2 Sampling 20Copyright European Committee for Standardization Provided by IHS under license with CENNot fo
17、r ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 14272:2011EN 14272:2011 (E) 3 A.3.3 Test pieces . 20A.3.4 Testing 20A.3.5 Exploitation of the results 21A.4 Derivation of estimated values for veneers 25A.4.1 General . 25A.4.2 Values obtained by testing . 25A.4.3 Imp
18、osed values 25A.5 Report . 25Annex B (normative) Practical spreadsheets to derive the properties 27B.1 General . 27B.2 Bending 28B.2.1 General . 28B.2.2 Main tables . 28B.2.3 Tables for strength values 31B.3 Tension and compression 33B.4 Panel shear 39B.5 Planar shear . 40B.5.1 General . 40B.5.2 Ava
19、ilable veneer values 40B.5.3 Veneer values not available . 42Annex C (informative) Example of bending strength 43C.1 Determination of the stress in the layers 43C.2 Determination of the panel strength 45Bibliography 47Copyright European Committee for Standardization Provided by IHS under license wit
20、h CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 14272:2011EN 14272:2011 (E) 4 Foreword This document (EN 14272:2011) has been prepared by Technical Committee CEN/TC 112 “Wood-based panels”, the secretariat of which is held by DIN. This European Standard
21、shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2012, and conflicting national standards shall be withdrawn at the latest by June 2012. Attention is drawn to the possibility that some of the elements of this docume
22、nt 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 14272:2002. Annex A and Annex B are normative. Compared to ENV 14272:2002, the following modifications have been made: a) calculation a
23、pplies to panels of any composition, symmetrical or not; b) values resulting for the panels can be used for calculation as characteristics values as required by EN 1995-1-1; c) new Annex A (normative) provides the derivation for the veneer values (basic values); d) new Annex B (normative) provides p
24、ractical spreadsheets to derive the properties; e) new Annex C (informative) gives an example of bending strength. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulga
25、ria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, 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. Copyright European
26、Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 14272:2011EN 14272:2011 (E) 5 1 Scope This European Standard specifies, for plywood panels of any composition, symmetrical or not, a calculatio
27、n method to derive some mechanical properties (strength and stiffness in bending, tension, compression, panel and planar shear) as well as density from the wood compounding the layers. NOTE Usually, the lay-up of the panels is symmetrical but, very often, the surface appearance of the face and the s
28、urface appearance of the back face differ, hence a difference between the mechanical properties of the respective veneers. Therefore, in this case, the composition is not mechanically symmetrical and a symmetry independent calculation method is needed. Provided that structural characteristic values
29、are taken for the layers, the resulting values for the panels can be used as characteristic values as required by EN 1995-1-1. Conversely, Annex A defines the procedures to derive the veneer properties, in bending, tension and compression, either from testing panels according to EN 789 and EN 1058 o
30、r from timber testing according to EN 408 or from imposed values defined in EN 338. Annex B provides practical spreadsheets, which are applications of the equations in the main part of this standard. Annex C provide an example for the calculation of bending strength, in accordance with Annex B. 2 No
31、rmative 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 325, Wood-based panels Dete
32、rmination of dimensions of test pieces EN 338:2009, Structural timber Strength classes EN 384, Structural timber Determination of characteristic values of mechanical properties and density EN 408, Timber structures Structural timber and glued laminated timber Determination of some physical and mecha
33、nical properties EN 789, Timber structures Test methods Determination of mechanical properties of wood based panels EN 1058, Wood-based panels Determination of characteristic 5-percentile values and characteristic mean values EN 12369-2, Wood-based panels Characteristic values for structural design
34、Part 2 Plywood EN 14358, Timber structures Calculation of characteristic 5-percentile values and acceptance criteria for a sample 3 Principle Using the mechanical properties of the wood species, which compound the layers (in this standard referred to as veneer or basic values), it consists in derivi
35、ng, by calculation, the mechanical properties of a panel. For bending, tension and compression, each layer property value, along and across the length of the panel, is weighted by a geometrical factor related to its weight in the panel cross section. Copyright European Committee for Standardization
36、Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 14272:2011EN 14272:2011 (E) 6 In this standard, where a value for a given property of the veneers is derived with a specified test method (including exploitation of the resu
37、lts), the models in this standard will provide a panel value for that property as if derived with the specified test method. EXAMPLE For instance, if, in a panel composition, a specified percentile of a bending property of veneers is determined with EN 789 and EN 1058, the calculated value of the be
38、nding property of the panel will be its specified percentile as if determined by using EN 789 and EN 1058. 4 Terms and definitions For the purposes of this document, the following terms and definitions apply. 4.1 characteristic strength population fifth percentile value relating to a temperature of
39、20 C and a relative humidity of 65 % 4.2 characteristic stiffness either the population fifth percentile or the mean value relating to a temperature of 20 C and a relative humidity of 65 % 4.3 characteristic density population fifth percentile value with mass and volume corresponding to equilibrium
40、at a temperature of 20 C and a relative humidity of 65 % either of the wood species or of the panels, single species or mixed species NOTE The density values found from calculation refer to the minimum acceptable density of veneers used in the lay-up of plywood. In the case of single species plywood
41、 these values are taken as the characteristic values for the plywood. In the case of mixed species plywood the characteristic value of density of the panel is calculated from the characteristic densities of the individual veneers according to the proportion of each species 4.4 veneer value or basic
42、value characteristic value of a property to be used for each layer in the equations of the calculation method NOTE Characteristic values of the wood species, along and across the grain, are fifth percentile values for strength but either mean values or fifth percentile values for stiffness (modulus
43、of elasticity). 4.5 reference panel value value of a given mechanical property of a panel composition NOTE It is to be used to derive the veneer value (or basic value) of the property. 5 Symbols 5.1 Main symbols A area (b tnom), in square millimetres f strength, in Newtons per square millimetre E mo
44、dulus of elasticity, in Newton per square millimetre Fs shear forces in a bending panel, in Newtons Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN 14272:2011EN 14272:2011
45、(E) 7 G modulus of rigidity, in Newtons per square millimetre b width of panel (equal to 1 in the equations), in millimetres t, thickness of layers, in millimetres T thickness of panels, in millimetres W section modulus, equal to ( )6/.2nomtb , in cubic millimetres I second moment of area, equal to
46、()12/.3nomtb , in millimetres to the fourth power density, in kilograms per cubic metre kamodification factor, appearance class grade z distance of the axis of a layer to the neutral axis of the panel, in millimetres distance of the neutral axis from either face of the panel, in millimetres Ecc ecce
47、ntricity factor, no dimension L/L relative elongation of the layers (bending, tension and compression) P property V strength or modulus, in Newton per square millimetre Rw in the set of layers, the weaker ratio of strength upon modulus for the properties of the wood species involved in the compositi
48、on of a panel Up stiffness of the panel s standard deviation 5.2 Subscripts m bending t tension c compression v panel shear r planar shear w applies to the lower ratio strength/modulus (f/E) of a property of a layer in a multi-species panel nom, mean nominal value and mean value respectively n number of layers of the panel (from top face to bottom face) i rank of layers from top face ax stands for neutral axis in bending density 0 parallel to lengt
