SIST EN 384:2010
(Main)Timber structures - Determination of characteristic values of mechanical properties and density
Timber structures - Determination of characteristic values of mechanical properties and density
This European Standard gives a method for determining characteristic values of mechanical properties and density, for defined populations of visual and/or mechanical strength grades of sawn timber. A method is also given for checking the strength of a timber sample against its designated value. The values determined in accordance with this standard for mechanical properties and density are suitable for assigning grades and species to the strength classes of EN 338.
Bauholz für tragende Zwecke - Bestimmung charakteristischen festigkeits-, Steifigkeits- und Rohdichtewerte
Diese Europäische Norm legt fest, wie charakteristische Werte für mechanische Eigenschaften und Rohdichtewerte von Schnittholz definierter Grundgesamtheiten von visuell und/oder maschinell nach der Festigkeit sortierte Sortierklassen zu bestimmen sind.
Außerdem wird ein Verfahren zur Überprüfung der Festigkeitswerte einer Probe zum Vergleich mit genormten Festigkeitswerten angegeben.
Die nach dieser Norm bestimmten mechanischen Eigenschaften und Rohdichtewerte sind für die Zuordnung der Holzarten und -klassen in die Festigkeitsklassen nach EN 338 geeignet.
ANMERKUNG 1 Für die Zuordnung der Holzarten und -klassen in die Festigkeitsklassen nach EN 338 ist die Bestimmung von nur drei charakteristischen Werten, d. h. Biegefestigkeit, Mittelwert des Elastizitätsmoduls, parallel zur Faserrichtung, und Rohdichte, erforderlich. Die übrigen Eigenschaften dürfen der in EN 338 angegebenen Tabelle entnommen werden.
ANMERKUNG 2 EN 1912 gibt Beispiele für die Zuordnung von Festigkeitsklassen von bewährten nationalen und regionalen visuellen Sortiergraden.
Structures en bois - Détermination des valeurs caractéristiques des propriétés mécaniques et de la masse volumique
La présente norme fournit une méthode permettant de déterminer des valeurs caractéristiques des propriétés
mécaniques et de la masse volumique pour des populations de bois définies de classe visuelle et/ou de
résistance mécanique.
Une méthode permettant de vérifier la résistance d’un échantillon de bois par rapport à une valeur spécifiée
est également indiquée.
Les valeurs des propriétés mécaniques et de la masse volumique déterminées conformément à la présente
norme permettent d’affecter des classes et des essences aux classes de résistance de l'EN 338.
NOTE Pour l’affectation des classes et des essences aux classes de résistance de l’EN 338, il suffit de déterminer
trois valeurs caractéristiques : à savoir la résistance à la flexion, le module d’élasticité moyen parallèle au grain, ainsi que
la masse volumique ; d’autres propriétés peuvent être extraites du tableau de l’EN 338.
Konstrukcijski les - Ugotavljanje značilnih vrednosti mehanskih lastnosti in gostote
Ta evropski standard podaja metodo za določevanje značilnih vrednostih mehanskih lastnosti in gostote za določeno populacijo razredov na podlagi vizualnega in/ali mehanskega razvrščanja v razrede trdnosti rezanega lesa. Metoda je prav tako podana za preverjanje trdnosti vzorca lesa z njegovo določeno vrednostjo. Vrednosti, določene v skladu s tem standardom za mehanske lastnosti in gostoto, so primerne za označevanje razredov in vrst za razrede trdnosti iz EN 338.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.JRVWRWHBauholz für tragende Zwecke - Bestimmung charakteristischen festigkeits-, Steifigkeits- und RohdichtewerteStructures en bois - Détermination des valeurs caractéristiques des propriétés mécaniques et de la masse volumiqueTimber structures - Determination of characteristic values of mechanical properties and density91.080.20Lesene konstrukcijeTimber structuresICS:Ta slovenski standard je istoveten z:EN 384:2010SIST EN 384:2010en,fr,de01-september-2010SIST EN 384:2010SLOVENSKI
STANDARDSIST EN 384:20041DGRPHãþD
SIST EN 384:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 384
April 2010 ICS 79.040 Supersedes EN 384:2004English Version
Structural timber - Determination of characteristic values of mechanical properties and density
Structures en bois - Détermination des valeurs caractéristiques des propriétés mécaniques et de la masse volumique
Bauholz für tragende Zwecke - Bestimmung charakteristischer Werte für mechanische Eigenschaften und Rohdichte This European Standard was approved by CEN on 4 March 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.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 384:2010: ESIST EN 384:2010
EN 384:2010 (E) 2 Contents Page Foreword .3Introduction .41 Scope .52 Normative references .53 Terms and definitions .54 Symbols and abbreviations .65 Mechanical properties determined from full-size specimens .75.1 Sampling .75.2 Testing .85.3 Analysis of data .85.3.1 Determination of sample 5-percentile for strength .85.3.2 Determination of the sample mean of modulus of elasticity .95.3.3 Reference conditions .95.3.4 Adjustment factors .95.4 Strength properties. 105.5 Modulus of elasticity . 116 Alternative methods of determining mechanical properties . 126.1 Bending strength and modulus of elasticity determined from small, clear hardwood specimens . 126.2 Other mechanical properties for hardwoods and softwoods . 126.2.1 General . 126.2.2 Tension strength parallel to grain and compression strength parallel to grain and shear strength . 126.2.3 Tension perpendicular to grain strength . 126.2.4 Compression perpendicular to grain strength . 126.2.5 Characteristic fifth percentile modulus of elasticity parallel to grain . 136.2.6 Mean modulus of elasticity perpendicular to grain . 136.2.7 Shear modulus . 137 Mechanical properties for other grades of hardwood and softwood . 138 Density . 139 Acceptance procedure for verification of a lot . 149.1 General . 149.2 Verification of mean values (e.g. mean modulus of elasticity) . 149.2.1 Method keeping the consumer's risk at 10 % . 149.2.2 Alternative method limiting the sample size for large COVs . 149.3 Verification of 5-percentile values (e.g. characteristic strength) . 159.3.1 Method with consumers risk equal to 10 % . 159.3.2 Alternative method limiting the sample size for large COVs . 1510 Report . 16Annex A (normative)
Form for declaring characteristic values . 17Bibliography . 19 SIST EN 384:2010
EN 384:2010 (E) 3 Foreword This document (EN 384:2010) has been prepared by Technical Committee CEN/TC 124 “Timber structures”, the secretariat of which is held by SFS. 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 2010, and conflicting national standards shall be withdrawn at the latest by October 2010. 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 384:2004. 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, 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. SIST EN 384:2010
EN 384:2010 (E) 4 Introduction In this revised edition, changes have been made to the equations giving the relativities between properties in 6.2.1, and the method of calculating the 5-percentile density. Also, the verification requirements in Clause 9 have been rewritten.
Structural codes can only function effectively if standard methods of determining the mechanical and physical properties exist.
Whilst total accuracy of characteristic values for any defined population is an aim, it is recognized that this is not achievable. A major aim of the procedures given in this standard is to produce characteristic values that are comparable in terms of the populations they represent. It is also important that the standard permits the use of as much existing test data as possible from various sampling and testing techniques.
Where methods are given to permit characteristic values to be determined from a less than ideal amount of structural size test data or from small, clear, defect-free specimen test data, reduction factors to reflect a lower degree of confidence are employed.
This standard covers the stages of population definition, sampling, testing and analysis and presentation of data in the determination of characteristic values. SIST EN 384:2010
EN 384:2010 (E) 5 1 Scope This European Standard gives a method for determining characteristic values of mechanical properties and density, for defined populations of visual and/or mechanical strength grades of sawn timber.
A method is also given for checking the strength of a timber sample against its designated value.
The values determined in accordance with this standard for mechanical properties and density are suitable for assigning grades and species to the strength classes of EN 338. NOTE 1 For assigning grades and species to the strength classes in EN 338 only three characteristic values, i.e. bending strength, mean modulus of elasticity parallel to grain and density, need to be determined, other properties may be taken from the table in EN 338. NOTE 2 EN 1912 gives examples of assignment to strength classes of established national or regional visual grades. 2 Normative 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 338, Structural timber — Strength classes EN 408, Timber structures — Structural timber and glued laminated timber — Determination of some physical and mechanical properties EN 1912, Structural timber
Strength classes
Assignment of visual grades and species EN 14081-1, Timber structures — Strength graded structural timber with rectangular cross section — Part 1: General requirements EN 14081-2, Timber structures — Strength graded structural timber with rectangular cross section — Part 2: Machine grading, additional requirements for initial type testing ISO 3131:1975, Wood — Determination of density for physical and mechanical tests 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 characteristic value generally, value that corresponds to a fractile of the statistical distribution of a timber property
NOTE For strength properties, modulus of elasticity and density the fractile is the 5-percentile. For modulus of elasticity, the mean value is also a characteristic value. 3.2 p-percentile value for which the probability of getting lower values is p % 3.3 population material for which the associated characteristic values are relevant SIST EN 384:2010
EN 384:2010 (E) 6 NOTE The population is defined by parameters such as species or species combination, source and strength grade. 3.4 sample number of specimens of one cross section size and from one population
NOTE See 5.1. 3.5 small clear test test to determine mechanical properties of small defect-free specimens 3.6 specimen piece of timber for testing 3.7 thickness lesser dimension perpendicular to the longitudinal axis of a piece of timber 3.8 width greater dimension perpendicular to the longitudinal axis of a piece of timber 3.9 depth dimension perpendicular to the longitudinal axis of a timber beam, in the plane of the bending forces 4 Symbols and abbreviations
af
distance between the inner load points of the bending test (in millimetres)
COV coefficient of variation
E
mean modulus of elasticity for one sample (in newtons per square millimetre)
E0,mean
mean characteristic value of modulus of elasticity parallel to grain (in newtons per square millimetre)
E0,05
5-percentile characteristic value of modulus of elasticity parallel to grain (in newtons per square millimetre)
E90,mean
mean characteristic value of modulus of elasticity perpendicular to grain (in newtons per square millimetre)
Emean,acc
mean modulus of elasticity for an acceptable quality lot (in newtons per square millimetre)
Emean,unacc
mean modulus of elasticity for an unacceptable quality lot (in newtons per square millimetre)
f strength property
fc,0,k
characteristic value of compression strength parallel to grain (in newtons per square millimetre)
fc,90,k
characteristic value of compression strength perpendicular to grain (in newtons per square millimetre)
fk
characteristic value of strength (in newtons per square millimetre) SIST EN 384:2010
EN 384:2010 (E) 7
fm,k
characteristic value of bending strength (in newtons per square millimetre)
ft,0,k
characteristic value of tensile strength parallel to grain (in newtons per square millimetre)
ft,90,k
characteristic value of tensile strength perpendicular to grain (in newtons per square millimetre)
f05
5-percentile value for each sample (in newtons per square millimetre)
f05,acc
5-percentile value for an acceptable quality lot (in newtons per square millimetre)
f05,unacc
5-percentile value for an unacceptable quality lot (in newtons per square millimetre)
f05
the mean value of f05 for several samples (in newtons per square millimetre)
fv,k
characteristic value of shear strength (in newtons per square millimetre)
Gmean
mean characteristic value of shear modulus (in newtons per square millimetre)
h
depth of a bending specimen or width of a tension specimen (in millimetres)
kh
factor for adjusting fk when h is different from 150 mm
kl
factor for adjusting length;
kq
factor for use when checking the quality of a graded sample
ks
factor for adjusting for the number and size of samples
kv
factor for adjusting for machine grading
l
span (in millimetres)
let
effective length for the test (in millimetres)
n
number of specimens in a sample
plim acceptable probability limit for strength
. producers risk
consumers risk
ρ
density (in kilograms per cubic metre)
ρk
characteristic density (5-percentile) (in kilograms per cubic metre)
ρ05
5-percentile density for a sample (in kilograms per cubic metre) 5 Mechanical properties determined from full-size specimens 5.1 Sampling Samples shall be selected from the population of timber graded visually or by machine to the requirements given in EN 14081-1.
SIST EN 384:2010
EN 384:2010 (E) 8 The test material shall be representative of the population. It shall represent the timber source, sizes, and quality that will be graded in production. Each sample shall be from one source. NOTE 1 For the derivation of settings for grading machines additional sampling requirements are given in EN 14081-2. Any known or suspected difference in the mechanical properties of the population distribution due to growth regions, sawmills, tree size or method of conversion shall be represented within the number of samples selected, by a similar proportion to their frequency in the population.
NOTE 2 The above should be the major influence in determining the number and size of samples. The number of specimens in each sample shall be not less than 40.
NOTE 3 Where samples are small and/or few in number the characteristic values will be penalized, see 5.4.
The cross section size of specimens shall be the same within a sample, but different for other samples, except where the test data are to be used to determine settings for a grading machine that measures size as part of its operation (see EN 14081-2). The number of sizes shall reflect the range of sizes to which the grading rules are applicable.
Test specimens for shear, tension perpendicular to grain and compression perpendicular to grain strengths are comparatively small and therefore shall be free of strength reducing characteri
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