Structural timber - 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 grades and/or strength classes of machine graded structural timber. Additionally it covers the stages of sampling, testing, analysis and presentation of the data.
The standard provides methods to derive strength, stiffness and density properties for structural timber from tests with defect-free specimen.
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 properties, i.e. bending or tension strength, modulus of elasticity parallel to grain in bending or tension and density need to be determined from test data, other properties can be calculated according to Table 2.
NOTE 2   EN 1912 gives examples of established visual grades assigned to strength classes.

Bauholz für tragende Zwecke - Bestimmung charakteristischer Werte für mechanische Eigenschaften und Rohdichte

Bois de structure - Détermination des valeurs caractéristiques des propriétés mécaniques et de la masse volumique

La présente Norme européenne fournit une méthode permettant de déterminer des valeurs caractéristiques des propriétés mécaniques et de la masse volumique, pour des populations définies de bois sciés classés en résistance visuellement et/ou mécaniquement. Elle couvre également les étapes relatives à l'échantillonnage, aux essais, à l'analyse et à la présentation des données.
La norme fournit des méthodes permettant de déterminer les caractéristiques de résistance, de rigidité et de masse volumique de bois pour usage structurel à partir d’éprouvettes exemptes de défauts.
Les valeurs des propriétés mécaniques et de la masse volumique déterminées conformément à la présente norme permettent d'affecter les classes et les essences aux classes de résistance de l'EN 338.
NOTE 1   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 ou à la traction, le module d'élasticité en flexion ou en traction axiale et la masse volumique  à partir de résultats d’essais; les autres propriétés peuvent être calculées conformément au Tableau 2.
NOTE 2   L'EN 1912 fournit des exemples d'affectation de classes visuelles établies à des classes de résistance.

Konstrukcijski les - Ugotavljanje karakterističnih vrednosti mehanskih lastnosti in gostote

Ta evropski standard podaja metodo za ugotavljanje karakterističnih vrednosti mehanskih lastnosti in gostote za opredeljene populacije razredov vizualnega razvrščanja in/ali trdnostnih razredov strojno razvrščenega konstrukcijskega lesa. Poleg tega zajema stopnje vzorčenja, preskušanja, analize in predstavitve podatkov.
Standard podaja metode za izpeljavo lastnosti trdnosti, togosti in gostote za konstrukcijski les iz preskusov z vzorcem brez napak.
Vrednosti, določene v skladu s tem standardom za mehanske lastnosti in gostoto, so primerne za dodeljevanje razredov in vrst trdnostnim razredom standarda EN 338.
OPOMBA 1: Za dodeljevanje razredov in vrst trdnostnim razredom iz standarda EN 338 je treba iz podatkov preskusa določiti le tri lastnosti, tj. upogibno ali natezno trdnost, modul elastičnosti, vzporeden z vlakni pri upogibanju ali napenjanju, in gostoto; druge lastnosti je mogoče izračunati v skladu s preglednico 2.
OPOMBA 2: EN 1912 podaja primere vzpostavljenih razredov vizualnega razvrščanja, dodeljenih trdnostnim razredom.

General Information

Status
Withdrawn
Publication Date
05-Dec-2018
Withdrawal Date
15-Aug-2022
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
01-Aug-2022
Due Date
24-Aug-2022
Completion Date
16-Aug-2022

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SLOVENSKI STANDARD
SIST EN 384:2016+A1:2019
01-januar-2019
1DGRPHãþD
SIST EN 384:2016

.RQVWUXNFLMVNLOHV8JRWDYOMDQMHNDUDNWHULVWLþQLKYUHGQRVWLPHKDQVNLKODVWQRVWLLQ

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Structural timber - Determination of characteristic values of mechanical properties and

density

Bauholz für tragende Zwecke - Bestimmung charakteristischer Werte für mechanische

Eigenschaften und Rohdichte
Bois de structure - Détermination des valeurs caractéristiques des propriétés
mécaniques et de la masse volumique
Ta slovenski standard je istoveten z: EN 384:2016+A1:2018
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
91.080.20 Lesene konstrukcije Timber structures
SIST EN 384:2016+A1:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 384:2016+A1:2019
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SIST EN 384:2016+A1:2019
EN 384:2016+A1
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2018
EUROPÄISCHE NORM
ICS 79.040 Supersedes EN 384:2016
English Version
Structural timber - Determination of characteristic values
of mechanical properties and density

Bois de structure - Détermination des valeurs Bauholz für tragende Zwecke - Bestimmung

caractéristiques des propriétés mécaniques et de la charakteristischer Werte für mechanische

masse volumique Eigenschaften und Rohdichte

This European Standard was approved by CEN on 30 January 2016 and includes Amendment 1 approved by CEN on 8 October

2018.

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-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 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 384:2016+A1:2018 E

worldwide for CEN national Members.
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SIST EN 384:2016+A1:2019
EN 384:2016+A1:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

Introduction .................................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and definitions ................................................................................................................................... 5

4 Symbols and abbreviations ......................................................................................................................... 6

5 Mechanical properties determined from full-size specimens ........................................................ 8

5.1 Sampling ............................................................................................................................................................. 8

5.2 Testing ................................................................................................................................................................. 8

5.3 Reference conditions ..................................................................................................................................... 8

5.3.1 Moisture content ............................................................................................................................................. 8

5.3.2 Bending strength ............................................................................................................................................. 8

5.3.3 Tension strength ............................................................................................................................................. 8

5.3.4 Density ................................................................................................................................................................ 8

5.4 Adjustment factors ......................................................................................................................................... 9

5.4.1 General ................................................................................................................................................................ 9

5.4.2 Moisture content ............................................................................................................................................. 9

5.4.3 Timber size and test length ......................................................................................................................... 9

5.4.4 Modulus of elasticity ................................................................................................................................... 10

5.4.5 Other adjustments ....................................................................................................................................... 10

5.5 Analysis of data ............................................................................................................................................. 10

5.5.1 Sub-sample analysis .................................................................................................................................... 10

5.5.2 Characteristic values ................................................................................................................................... 11

6 Bending strength and modulus of elasticity determined from small, clear hardwood

specimens ....................................................................................................................................................... 13

7 Other mechanical properties for hardwoods and softwoods ...................................................... 13

8 Report ............................................................................................................................................................... 15

Annex A (normative) Requirements for reports for visual grading assignment ............................... 16

Bibliography ................................................................................................................................................................. 19

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SIST EN 384:2016+A1:2019
EN 384:2016+A1:2018 (E)
European foreword

This document (EN 384:2016+A1:2018) has been prepared by Technical Committee CEN/TC 124

“Timber structures”, the secretariat of which is held by AFNOR.

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 May 2019, and conflicting national standards shall be

withdrawn at the latest by May 2019.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document includes Amendment 1 approved by CEN on 2018-10-08.
This document supersedes !EN 384:2016".

The start and finish of text introduced or altered by amendment is indicated in the text by tags !".

!Deleted text"

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, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
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SIST EN 384:2016+A1:2019
EN 384:2016+A1:2018 (E)
Introduction

Structural design codes can only function effectively if standard methods of determining the mechanical

and physical properties exist. The aim of the procedures given in this standard is to derive

characteristic values that are comparable in terms of the populations they represent. 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, reduction factors to reflect a lower degree of confidence are

employed.
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SIST EN 384:2016+A1:2019
EN 384:2016+A1:2018 (E)
1 Scope

This European Standard gives a method for determining characteristic values of mechanical properties

and density, for defined populations of visual grades and/or strength classes of machine graded

structural timber. Additionally it covers the stages of sampling, testing, analysis and presentation of the

data.

The standard provides methods to derive strength, stiffness and density properties for structural

timber from tests with defect-free specimen.

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 properties, i.e. bending or

tension strength, modulus of elasticity parallel to grain in bending or tension and density need to be determined

from test data, other properties can be calculated according to Table 2.

NOTE 2 EN 1912 gives examples of established visual grades assigned to strength classes.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. 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 13183-2, Moisture content of a piece of sawn timber — Part 2: Estimation by electrical resistance

method

EN 13183-3, Moisture content of a piece of sawn timber — Part 3: Estimation by capacitance method

EN 14081-1:2016, 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

EN 14081-3, Timber structures — Strength graded structural timber with rectangular cross section —

Part 3: Machine grading; additional requirements for factory production control

EN 14358:2016, Timber structures — Calculation and verification of characteristic values

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
characteristic value

representative value of a material property used for design, which is based either on 5-percentile values

(e.g. strength properties and density) or mean values (e.g. modulus of elasticity)

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SIST EN 384:2016+A1:2019
EN 384:2016+A1:2018 (E)
3.2
p-percentile
value for which the probability of getting lower values is p %
3.3
population
timber for which the characteristic values are relevant
3.4
timber source

identifiable geographical origin of a species or species combination from which timber is, or is intended

to be, strength graded
3.5
sample

a number of ungraded specimens of one timber species or species combination, one source, with sizes

and quality representative of the timber population (see 5.1)
3.6
sub-sample
part of one or more samples consisting of specimens of one grade
3.7
small clear test
test to determine mechanical properties of small defect-free specimens
3.8
specimen
piece of timber from which the test piece is taken
3.9
thickness
lesser dimension perpendicular to the longitudinal axis of a piece of timber
3.10
width
larger dimension perpendicular to the longitudinal axis of a piece of timber
3.11
depth

in the case of bending, cross-sectional dimension parallel to the direction of loading; in the case of

tension, the width
4 Symbols and abbreviations
a distance between the inner load points of the bending test (in mm)
E modulus of elasticity parallel to grain (in N/mm )

E mean characteristic value of modulus of elasticity parallel to grain (in N/mm )

0,mean

E 5-percentile characteristic value of modulus of elasticity parallel to grain (in N/mm )

0,k

E mean characteristic value of modulus of elasticity perpendicular to grain (in N/mm )

90,mean
mean modulus of elasticity for one sub-sample (in N/mm )
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SIST EN 384:2016+A1:2019
EN 384:2016+A1:2018 (E)
lowest mean modulus of elasticity of all sub-samples (in N/mm )
i,min
E global modulus of elasticity in bending (in N/mm )
m,global
E local modulus of elasticity in bending (in N/mm )
m,local
f strength property

f 5- percentile characteristic value of compression strength parallel to grain (in N/mm )

c,0,k

f 5- percentile characteristic value of compression strength perpendicular to grain (in

c,90,k
N/mm )
f 5- percentile characteristic value of strength (in N/mm )
f 5- percentile characteristic value of bending strength (in N/mm )
m,k

f 5- percentile characteristic value of tension strength parallel to grain (in N/mm )

t,0,k

f 5- percentile characteristic value of tension strength perpendicular to grain (in N/mm )

t,90,k
f 5-percentile value for each sub-sample (in N/mm )
05,i
f lowest 5-percentile value of all sub-samples (in N/mm )
05,i,min
f 5- percentile characteristic value of shear strength (in N/mm )
v,k
G mean characteristic value of shear modulus (in N/mm )
mean
h depth (in mm)
k factor for adjusting f when h is not 150 mm
k factor for adjusting f when test span is not 18 h
k factor to adjust for the number of sub-samples

k factor to allow for the lower variability of f values between sub-samples for machine

v 05
grades in comparison with visual grades
span (in mm)
 effective length for the test (in mm)
n total number of specimens
n number of specimens in a sub-sample
n number of sub-samples
u moisture content (in %)
u reference moisture content, normally at 12 %
ref
ρ density (in kg/m )
ρ mean density (in kg/m )
mean
ρ characteristic density (5-percentile) (in kg/m )
ρ 5-percentile density for a sub-sample (in kg/m )
05,i
ρ lowest 5-percentile density of all sub-samples (in kg/m )
05,i,min
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SIST EN 384:2016+A1:2019
EN 384:2016+A1:2018 (E)
5 Mechanical properties determined from full-size specimens
5.1 Sampling
The sampling shall be representative of the population.

Any known or suspected difference in the mechanical properties of the population due to e.g. sawmills,

tree size, countries or silviculture shall be represented within the sampling by a similar proportion to

their frequency in the population. This shall be the major influence in determining the number and size

of samples.

Samples shall be selected from one source of timber and shall be graded visually or by machine to sub-

samples according to the requirements given in EN 14081-1.

For visual grading, each sub-sample shall consist of at least 40 specimens and be of one source.

For bending and tension parallel to grain tests, specimens shall have a sufficient length so that critical

defects can be located in the critical test zone (see 5.2). A length of at least 30 times the depth or 3.6 m

whichever is the lesser meets this requirement.

For the determination of strengths perpendicular to the grain and shear strength clear specimens shall

be sampled.
5.2 Testing

Testing shall be carried out in accordance with EN 408 for strength, modulus of elasticity, density and

moisture content. For bending parallel to grain, tension parallel to grain or modulus of elasticity, a

critical section shall be selected in each piece of timber. This section is the position at which fai

...

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