SIST EN 384:2016
(Main)Structural timber - Determination of characteristic values of mechanical properties and density
Structural timber - Determination of characteristic values of mechanical properties and density
This standard gives a method for determining characteristic values of mechanical properties and density, for defined populations of visual grades and/or mechanical strength classes of sawn timber. Additionally it covers the stages of sampling, testing, analysis and presentation of the data.
A method is also given for checking the strength of a timber population 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 or tension strength, mean modulus of elasticity parallel to grain in bending or tension and density need to be determined, other properties can be calculated according to Tab. 6.2.
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
Diese Norm legt fest, wie charakteristische Werte für mechanische Eigenschaften und Rohdichtewerte von definierten Holzgrundgesamtheiten visueller Sortierklassen und/oder mechanischer Festigkeitsklassen von Schnittholz zu bestimmen sind. Zusätzlich umfasst die Norm die Stufen von Probenahme, Prüfung, Analyse und Darstellung der Daten.
Außerdem wird ein Verfahren zur Überprüfung der Festigkeitswerte einer Grundgesamtheit von Bauholz zum Vergleich mit vorgegebenen Festigkeitswerten angegeben.
Die nach dieser Norm bestimmten mechanischen Eigenschaften und Rohdichtewerte sind für die Zuordnung der Holzarten und Sortierklassen in die Festigkeitsklassen nach EN 338 geeignet.
ANMERKUNG 1 Für die Zuordnung der Holzarten und Sortierklassen in die Festigkeitsklassen nach EN 338 ist die Bestimmung von nur drei charakteristischen Werten, d. h. Biege- oder Zugfestigkeit, Mittelwert des Biege- oder Zug-Elastizitätsmoduls in Faserrichtung und die Rohdichte erforderlich; die sonstigen Eigenschaften können nach der Tabelle in 6.2 berechnet werden.
ANMERKUNG 2 EN 1912 gibt Beispiele für die Zuordnung von bestehenden visuellen Sortierklassen zu Festigkeits-klassen.
Bois de structure - 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 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.
Une méthode permettant de vérifier la résistance d'une population de bois par rapport à une valeur spécifiée est également fournie.
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 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 moyen en flexion ou en traction axiale et la masse volumique ; d'autres propriétés peuvent être calculées conformément au Tableau 6.2.
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 standard podaja metodo za ugotavljanje karakterističnih vrednosti mehanskih lastnosti in gostote za opredeljene populacije razredov vizualnega razvrščanja in/ali razredov mehanske trdnosti žaganega lesa. Poleg tega zajema stopnje vzorčenja, preskušanja, analize in predstavitve podatkov.
Podana je tudi metoda za preverjanje trdnosti populacije lesa glede na njegovo označeno vrednost.
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 določiti le tri karakteristične vrednosti, 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 6.2
OPOMBA 2: EN 1912 podaja primere vzpostavljenih razredov vizualnega razvrščanja, dodeljenih trdnostnim razredom.
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.JRVWRWHBauholz für tragende Zwecke - Bestimmung charakteristischer Werte für mechanische Eigenschaften und RohdichteBois de structure - Détermination des valeurs caractéristiques des propriétés mécaniques et de la masse volumiqueStructural timber - Determination of characteristic values of mechanical properties and density91.080.20Lesene konstrukcijeTimber structures79.040Les, hlodovina in žagan lesWood, sawlogs and sawn timberICS:Ta slovenski standard je istoveten z:EN 384:2016SIST EN 384:2016en,fr,de01-november-2016SIST EN 384:2016SLOVENSKI
STANDARDSIST EN 384:20101DGRPHãþD
SIST EN 384:2016
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 384
August
t r s x ICS
y {ä r v r Supersedes EN
u z vã t r s rEnglish Version
Structural timber æ Determination of characteristic values of mechanical properties and density Bois de structure æ Détermination des valeurs caractéristiques des propriétés mécaniques et de la masse volumique
Bauholz für tragende Zwecke æ Bestimmung charakteristischer Werte für mechanische Eigenschaften und Rohdichte This European Standard was approved by CEN on
u r January
t r s xä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey andUnited Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
9
t r s x CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
u z vã t r s x ESIST EN 384:2016
EN 384:2016 (E) 2 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
SIST EN 384:2016
EN 384:2016 (E) 3 European foreword This document (EN 384:2016) 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 February 2017, and conflicting national standards shall be withdrawn at the latest by February 2017. 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 384:2010. Compared to EN 384:2010, the following modifications have been made: — the definitions have been revised; — the adjustments of test results to the reference moisture content are presented as equations; — the equations for determining other properties from properties derived by testing have been changed; — regarding the determination of 5 %-percentiles the standard has been adopted to the revised EN 14358; — the procedure for verification of a lot has been transferred to EN 14358. 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 384:2016
EN 384:2016 (E) 4 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. SIST EN 384:2016
EN 384:2016 (E) 5 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) SIST EN 384:2016
EN 384:2016 (E) 6 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 af distance between the inner load points of the bending test (in mm) E0 modulus of elasticity parallel to grain (in N/mm2) E0,mean mean characteristic value of modulus of elasticity parallel to grain (in N/mm2) E0,k 5-percentile characteristic value of modulus of elasticity parallel to grain (in N/mm2) E90,mean mean characteristic value of modulus of elasticity perpendicular to grain (in N/mm2) Ei mean modulus of elasticity for one sub-sample (in N/mm2) SIST EN 384:2016
EN 384:2016 (E) 7 Ei,min lowest mean modulus of elasticity of all sub-samples (in N/mm2) Em,global global modulus of elasticity in bending (in N/mm2) Em,local local modulus of elasticity in bending (in N/mm2) f strength property fc,0,k 5- percentile characteristic value of compression strength parallel to grain (in N/mm2) fc,90,k 5- percentile characteristic value of compression strength perpendicular to grain (in N/mm2) fk 5- percentile characteristic value of strength (in N/mm2) fm,k 5- percentile characteristic value of bending strength (in N/mm2) ft,0,k 5- percentile characteristic value of tension strength parallel to grain (in N/mm2) ft,90,k 5- percentile characteristic value of tension strength perpendicular to grain (in N/mm2) f05,i 5-percentile value for each sub-sample (in N/mm2) f05,i,min lowest 5-percentile value of all sub-samples (in N/mm2) fv,k 5- percentile characteristic value of shear strength (in N/mm2) Gmean mean characteristic value of shear modulus (in N/mm2) h depth (in mm) kh factor for adjusting f when h is not 150 mm kl factor for adjusting f when test span is not 18 h kn factor to adjust for the number of sub-samples kv factor to allow for the lower variability of f05 values between sub-samples for machine grades in comparison with visual grades span (in mm) et effective length for the test (in mm) n total number of specimens ni number of specimens in a sub-sample ns number of sub-samples u moisture content (in %) u ref reference moisture content, normally at 12 %
density (in kg/m3)
mean mean density (in kg/m3) k characteristic density (5-percentile) (in kg/m3) 05,i 5-percentile density for a sub-sample (in kg/m3) 05,i,min lowest 5-percentile density of all sub-samples (in kg/m3) SIST EN 384:2016
EN 384:2016 (E) 8 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 les
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