1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 14081-2:2010+A1:2012Timber structures Strength graded structural timber with rectangular cross sectionPart 2: Machine grading; additional r e q u i r e m e n t s f o r i n
2、i t i a l t y p e t e s t i n gBS EN 14081-2:2010+A1:2012National forewordThis British Standard is the UK implementation ofEN 14081-2:2010+A1:2012. It supersedes BS EN 14081-2:2010,which is withdrawn.The start and finish of text introduced or altered by amendment is indicated in the text by tags. Ta
3、gs indicating changes to CEN text carry the number of the CEN amendment. For example, text altered by CEN amendment A1 is indicated by !“.The UK participation in its preparation was entrusted to Technical Committee B/518, Structural timber.A list of organizations represented on this committee can be
4、 obtainedon request to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application. The British Standards Institution 2013.Published by BSI Standards Limited 2013.ISBN 978 0 580 78744 7 ICS 79.040 Compliance
5、with a British Standard cannot confer immunityfrom legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2010.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARD28 February 2013 Implementation
6、of CEN amendment A1:2012EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 14081-2:2010+A1 November 2012 ICS 79.040 Supersedes EN 14081-2:2010English Version Timber structures - Strength graded structural timber with rectangular cross section - Part 2: Machine grading; additional requirements for
7、initial type testing Structures en bois - Bois de structure de section rectangulaire class selon la rsistance - Partie 2: Classement mcanique - Exigences supplmentaires concernant les essais de type initiaux Holzbauwerke - Nach Festigkeit sortiertes Bauholz fr tragende Zwecke mit rechteckigem Quersc
8、hnitt - Teil 2: Maschinelle Sortierung; zustzliche Anforderungen an die Erstprfung This European Standard was approved by CEN on 5 May 2010 and includes Amendment 1 approved by CEN on 8 October 2012. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the condit
9、ions 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
10、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 standa
11、rds 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, Slov
12、enia, 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-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide f
13、or CEN national Members. Ref. No. EN 14081-2:2010+A1:2012: EEN 14081-2:2010+A1:2012 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Terms and definitions .54 Symbols 65 Requirements for strength grading machines 76 Additional requirements for initial type testing for
14、machine controlled systems 86.1 General 86.2 Requirements for the derivation and verification of machine settings86.3 Machine installation check 147 Additional requirements for initial type testing for output controlled systems . 157.1 General . 157.2 Requirements for the assessment of initial setti
15、ngs 15Annex A (normative) Calculation of elementary cost matrix values for 6.2.4.8 . 17A.1 General . 17A.2 Factors for wrongly upgraded pieces. 17A.3 Factors for wrongly downgraded pieces . 17Annex B (informative) Guidance on the procedure of initial type testing for machine controlled systems 19B.1
16、 Introduction . 19B.2 Guidance 19Bibliography . 21BS EN 14081-2:2010+A1:2012EN 14081-2:2010+A1:2012 (E) 3 Foreword This document (EN 14081-2:2010+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
17、be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 2013, and conflicting national standards shall be withdrawn at the latest by May 2013. Attention is drawn to the possibility that some of the elements of this document may b
18、e 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 14081-2:2010.“ This document includes Amendment 1 approved by CEN on 8 October 2012. The start and finish of text introduced or altered by amen
19、dment is indicated in the text by tags !“. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). Other parts of the EN 14081 series are: EN 14081-1, Timber structures St
20、rength graded structural timber with rectangular cross section Part 1: General requirements; EN 14081-3, Timber structures Strength graded structural timber with rectangular cross section Part 3: Machine grading; additional requirements for factory production control EN 14081-4, Timber structures St
21、rength graded structural timber with rectangular cross section Part 4: Machine grading Grading machine settings for machine controlled systems According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Stand
22、ard: 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, Spa
23、in, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 14081-2:2010+A1:2012EN 14081-2:2010+A1:2012 (E) 4 Introduction Machine grading is in common use in a number of countries. The countries use two basic systems, referred to as “output controlled“ and “machine controlled“. Both systems requi
24、re a visual override inspection to cater for strength-reducing characteristics that are not automatically sensed by the machine. The output-controlled system is suitable for use where the grading machines are situated in sawmills grading limited sizes, species and grades in repeated production runs
25、of around one working shift or more. This enables the system to be controlled by testing timber specimens from the daily output. These tests together with statistical procedures are used to monitor and adjust the machine settings to maintain the required strength properties for each strength class.
26、With this system it is permissible for machine approval requirements to be less demanding and for machines of the same type to have non-identical performance. The machine controlled system was developed in Europe. Because of the large number of sizes, species and grades used it was not possible to c
27、arry out quality control tests on timber specimens drawn from production. The system relies therefore on the machines being strictly assessed and controlled, and on considerable research effort to derive the machines settings, which remain constant for all machines of the same type. The acceptabilit
28、y of grading machines and the derivation of settings rely on statistical procedures and the results will therefore depend on the method used. For this reason this document gives appropriate statistical procedures. The requirements in this European Standard are based on machines in current use and on
29、 future types of machines as far as these can be foreseen. It is recognised that additional clauses or standards may be required if unforeseen developments take place. BS EN 14081-2:2010+A1:2012EN 14081-2:2010+A1:2012 (E) 5 1 Scope This European Standard specifies requirements, additional to those i
30、n EN 14081-1, for initial type testing of machine graded structural timber with rectangular cross sections shaped by sawing, planing or other methods, and having deviations from the target sizes corresponding to EN 336. This includes requirements for strength grading machines and test equipment for
31、proof loading graded material. 2 Normative references The following referenced documents are indispensable for the application of this European Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendme
32、nts) applies. EN 338, Structural timber Strength classes EN 384, Structural timber Determination of characteristic values of mechanical properties and density EN 408:2003, Timber structures Structural timber and glued laminated timber Determination of some physical and mechanical properties !EN 1408
33、1-1, Timber structures Strength graded structural timber with rectangular cross section Part 1: General requirements“ EN 14081-3, Timber structures Strength graded structural timber with rectangular cross section Part 3: Machine grading; additional requirements for factory production control EN 1408
34、1-4, Timber structures Strength graded structural timber with rectangular cross section Part 4: Machine grading Grading machine settings for machine controlled systems 3 Terms and definitions For the purposes of this document, the terms and definitions given !in EN 14081-1 and the following apply.“
35、3.1 characteristic strength population 5-percentile value obtained from the results of tests with a duration of (300 120) s using test pieces at an equilibrium moisture content resulting from a temperature of 20 C and a relative humidity of 65 % 3.2 characteristic stiffness population mean value obt
36、ained under the same test conditions as defined in 3.1 3.3 critical feed speed speed within the intended usable range at which the grading machine is least accurate in measuring its indicating property 3.4 depth dimension perpendicular to the longitudinal axis of a timber beam, in the plane of the b
37、ending forces BS EN 14081-2:2010+A1:2012EN 14081-2:2010+A1:2012 (E) 6 3.5 grade determining property mechanical or physical property for which a particular value of that property should be achieved for the material to be assigned to that grade, e.g. bending strength, mean modulus of elasticity and d
38、ensity for the strength classes of EN 338 3.6 indicating property IP measurement or combination of measurements made by the grading machine, which are closely related to one or more of the grade determining properties NOTE For grading machines which compute and predict values of the grade determinin
39、g properties directly from numerous measuring devices, the indicating property may be a predicted value of a grade determining property. 3.7 optimum grade highest grade, of those for which settings are required, to which a piece of timber can be assigned, such that the grade determining properties o
40、f the graded sample will meet the values required for the grade 3.8 settings values of the parameters used to set the machine to grade timber, which are mathematically related to the indicating property 3.9 sub-sample number of specimens of timber of one species or species combination, from one grow
41、th area or source of production 3.10 thickness lesser dimension perpendicular to the longitudinal axis of a piece of timber 4 Symbols b width of cross section (in millimetres) E theoretical modulus of elasticity (in newtons per square millimetre) Epactual modulus of elasticity measured in a proof lo
42、ad test (in newtons per square millimetre) Eassignedmean modulus of elasticity for assigned grade (in newtons per square millimetre) Eoptimummean modulus of elasticity for optimum grade (in newtons per square millimetre) E0,meancharacteristic mean modulus of elasticity parallel to grain (in newtons
43、per square millimetre) F applied force (in newtons) Fpproof load (in newtons) fm,kcharacteristic bending strength (in newtons per square millimetre) fpproof stress (in newtons per square millimetre) h depth of cross section (in millimetres) BS EN 14081-2:2010+A1:2012EN 14081-2:2010+A1:2012 (E) 7 khs
44、ize factor l span (in millimetres) t thickness (in millimetres) w deflection or deformation (in millimetres) achachieved safety index tartarget safety index deflection (in millimetres) mean value of bending strength for the optimum or assigned strength classes (in newtons per square millimetre) 5 Re
45、quirements for strength grading machines 5.1 The machine shall be of a type that meets the requirements given in Clauses 5 and 6 if it is part of a machine-controlled system, or Clauses 5 and 7 if it is part of an output controlled system. It shall be installed and set up according to the manufactur
46、ers specification and to any additional requirements resulting from the tests given here. In addition, except when a grading machine operates by measuring the bending stiffness of timber, the installation and calibration shall be checked by the use of control planks, using the procedures given in EN
47、 14081-3 under requirements for the use of control planks. 5.2 The following information shall be provided in the manufacturers specification for the machine: a) specification and description of the mechanical and electrical operation of the machine, and the software (this includes information on da
48、ta processing such as smoothing of the output signals) used by the machine to grade timber; b) range of environmental conditions under which the machine will operate; c) installation, maintenance and operating instructions; d) method, extent and frequency of calibration procedures, including the use
49、 of control planks if applicable; e) species populations, sizes, tolerances, surface finish, moisture content, grades, environmental operating temperature range, throughput speed, and limits of warp of the timber to be graded; f) manufacturing tolerances of the machine; g) checking and adjustment procedures for all components that may affect the machines grading accuracy. 5.3 Manufacturing tolerances and transducer accuracy tolerances shall ensure
