EN 14081-2:2010

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Holzbauwerke - Nach Festigkeit sortiertes Bauholz für tragende Zwecke mit rechteckigem Querschnitt - Teil 2: Maschinelle Sortierung; zusätzliche Anforderungen an die ErstprüfungStructures en bois - Bois de structure à section rectangulaire classé selon la résistance - Partie 2: Classement mécanique - Exigences supplémentaires concernant les essais de type initiauxTimber structures - Strength graded structural timber with rectangular cross section - Part 2: Machine grading; additional requirements for initial type testing91.080.20Lesene konstrukcijeTimber structures79.040Les, hlodovina in žagan lesWood, sawlogs and sawn timberICS:Ta slovenski standard je istoveten z:EN 14081-2:2010SIST EN 14081-2:2011en,fr,de01-april-2011SIST EN 14081-2:2011SLOVENSKI
STANDARDSIST EN 14081-2:20061DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14081-2
June 2010 ICS 79.040 Supersedes EN 14081-2:2005English Version
Timber structures - Strength graded structural timber with rectangular cross section - Part 2: Machine grading; additional requirements for initial type testing
Structures en bois - Bois de structure à section rectangulaire classé selon la résistance - Partie 2: Classement mécanique - Exigences supplémentaires concernant les essais de type initiaux
Holzbauwerke - Nach Festigkeit sortiertes Bauholz für tragende Zwecke mit rechteckigem Querschnitt - Teil 2: Maschinelle Sortierung - Zusätzliche Anforderungen an die Erstprüfung This European Standard was approved by CEN on 5 May 2010.
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 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 Management Centre has the same status as the official versions.
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Calculation of elementary cost matrix values for 6.2.4.8 . 17A.1General . 17A.2Factors for wrongly upgraded pieces. 17A.3Factors for wrongly downgraded pieces . 17Annex B (informative)
Guidance on the procedure of initial type testing for machine controlled systems . 19B.1 Introduction . 19B.2 Guidance . 19Bibliography . 21 SIST EN 14081-2:2011

65 % 3.2 characteristic stiffness population mean value obtained 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 bending forces SIST EN 14081-2:2011

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 determining 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 of 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 growth 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)
Ep actual modulus of elasticity measured in a proof load test (in newtons per square millimetre)
Eassigned mean modulus of elasticity for assigned grade (in newtons per square millimetre) Eoptimum mean modulus of elasticity for optimum grade (in newtons per square millimetre) E0,mean characteristic mean modulus of elasticity parallel to grain (in newtons per square millimetre)
F applied force (in newtons)
Fp proof load (in newtons)
fm,k characteristic bending strength (in newtons per square millimetre)
fp proof stress (in newtons per square millimetre)
h depth of cross section (in millimetres) SIST EN 14081-2:2011

w deflection or deformation (in millimetres)
βach achieved safety index βtar target safety index δ deflection (in millimetres) µ mean value of bending strength for the optimum or assigned strength classes (in newtons per square millimetre) 5 Requirements 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 manufacturer's 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 14081-3 under requirements for the use of control planks. 5.2 The following information shall be provided in the manufacturer's specification for the machine: a) specification and description of the mechanical and electrical operation of the machine, and the software (this includes information on data 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 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 machine’s grading accuracy. 5.3 Manufacturing tolerances and transducer accuracy tolerances shall ensure that production machines meet the requirements of this European Standard, and are compatible with grade settings derived for the machine type. 5.4 The grading machine shall not damage the timber during the grading operation to an extent that it affects the intended use of the timber. NOTE For example, in bending type machines, damage should not be caused by large compression perpendicular to grain stresses and/or large bending stresses. SIST EN 14081-2:2011

To derive settings for a new machine type and/or a new species (or species combination) or growth area, the total test sample shall be selected as a minimum number of four sub-samples (see 3.9), to represent the range of timber for which the settings are applicable (see EN 14081-1 under the requirements for machine grading). The minimum number of pieces in a sub-sample shall be 100. The minimum number of pieces in the total test sample shall be 900 for the derivation of settings for the full range of grades and sizes of a grading machine. To derive settings for new species for a machine that has previously met the requirements of this European Standard with different species, a minimum of 450 pieces shall be required. To test whether existing settings in EN 14081-4 are acceptable for use with a new growth area of the same species, the new growth area shall supply a minimum of two sub-samples (see first paragraph of this clause) each containing a minimum of 100 pieces. Each piece shall be graded by the machine using the existing settings and then tested to determine the grade determining properties as given in EN 384 using the kv (bending strength only) factor on strength and the 0,95 factor on E0,mean , but in addition, the use of ks also for E0,mean . The grade determining properties shall equal or exceed those required for the grade. SIST EN 14081-2:2011

a) number of grades and sizes to be graded. At least three sizes shall be tested; b) level of the grades; NOTE 2 Grades with very high critical properties, e.g. above strength class C30, should require more test data because errors in the model are more significant. c) strength and/or stiffness requirement for the strength class to be graded compared to the grade determining property range within the sample. Where the characteristic properties of almost all the timber sample meet the requirements for the grade being tested, the grades assigned by
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