EN 14251:2003

Structural round timber - Test methods

This standard applies for structural round wood timber other than specified in EN 12509.
This test standard specifies test methods for determining the following properties of structural round timber; the bending strength, modulus of elasticity in bending; the compressive strength parallel to the grain and modulus of elasticity in compression parallel to the grain.
In addition, the determination of dimensions, moisture content and density is specified. The methods apply to debarked round timber.
This standard is not intended for quality-control test purposes.

Rundholz für bauliche Zwecke - Prüfverfahren

Diese Norm gilt für den Einsatz von Rundholz für andere als die in EN 12509 festgelegten baulichen Zwecke.
Diese Prüfnorm legt Prüfverfahren zur Bestimmung folgender Eigenschaften von Rundholz für bauliche Zwecke fest: Biegefestigkeit, Biege-Elastizitätsmodul, Druckfestigkeit in Faserrichtung und Elastizitätsmodul bei Druckbeanspruchung in Faserrichtung.
Zusätzlich werden Verfahren zur Bestimmung der Maße, des Feuchtegehalts und der Dichte festgelegt. Die Verfahren gelten für entrindetes Rundholz.
Diese Norm ist nicht für die Anwendung in der Qualitätskontrolle vorgesehen.

Bois de structure rond - Méthodes d'essai

La présente norme s'applique aux usages structurels du bois rond non spécifiés dans l'EN 12509.
La présente norme d'essai spécifie les méthodes d'essai permettant de déterminer les propriétés suivantes du bois de structure rond : résistance à la flexion, module d'élasticité en flexion, résistance à la compression parallèlement au fil et module d'élasticité en compression parallèlement au fil.
De plus, les dimensions, la teneur en humidité et la masse volumique sont spécifiées. Les méthodes s'appliquent au bois rond écorcé.
La présente norme n'a pas pour objet de servir aux essais de contrôle qualité.

Okrogli konstrukcijski les – Preskusne metode

General Information

• Status: Published
• Publication Date: 02-Dec-2003
• Withdrawal Date: 29-Jun-2004
• ICS: 79.040 - Wood, sawlogs and sawn timber
• ICS: 91.080.20 - Timber structures
• Technical Committee: CEN/TC 124 - Timber structures
• Drafting Committee: CEN/TC 124/WG 1 - Test methods
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 17-May-2021
• Completion Date: 14-Apr-2025
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Directive: 89/106/EEC - Construction products
• Mandate: M/112 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on structural timber products
• Ref Project: SIST EN 14251:2004 - Structural round timber - Test methods

Overview

EN 14251:2003 is a European standard developed by the European Committee for Standardization (CEN) that specifies test methods for structural round timber excluding those covered by EN 12509. This standard focuses on assessing key mechanical properties of debarked round timber used in construction, such as:

• Bending strength
• Modulus of elasticity in bending
• Compressive strength parallel to the grain
• Modulus of elasticity in compression parallel to the grain

In addition, the standard outlines procedures for determining moisture content, density, and dimensions of test specimens. It is important to note that this standard is intended for accurate material property determination rather than quality control testing.

Key Topics

EN 14251:2003 addresses several critical topics necessary for structural round timber evaluation:

• Test specimen preparation: The standard mandates that test pieces are conditioned at a controlled environment (20 ± 2 °C and 65 ± 5% relative humidity) until constant mass is achieved to ensure accuracy in testing.
• Moisture content determination: Proper moisture measurement is essential since moisture affects timber's mechanical properties and dimensional stability.
• Density measurement: A cross-sectional disk, free from knots or resin pockets, is used to calculate density with accurate dimension measurements.
• Dimensions: All dimension measurements must be performed with 1% accuracy on conditioned specimens, noting any deviations in cross-section or taper.
• Bending tests: Conducted as symmetrical two-point loading over a span of 18 times the nominal diameter to measure bending strength and modulus of elasticity.
• Compression tests: Separate procedures for determining compressive strength and modulus of elasticity in compression parallel to the grain, using full cross-section samples 6 times nominal diameter in length.
• Test reporting: Detailed reporting requirements including species, grade, size, origin, test setup, and results to ensure traceability and reproducibility.

Key equations are provided for calculating bending strength, compressive strength, and modulus of elasticity values, emphasizing the importance of consistent loading rates and deformation measurements.

Applications

EN 14251:2003 is fundamental for:

• Structural engineers and designers: Provides reliable test methods to characterize the mechanical properties of round timber for safe and efficient design of timber structures.
• Material laboratories: Standardizes procedures for laboratory testing of structural round timber properties, ensuring uniformity in data collection and reporting.
• Quality assessment labs: While not intended for routine quality control, the standard supports in-depth property studies to guide grading and specification standards.
• Timber manufacturers and suppliers: Enables better product classification based on standardized property data relevant to load-bearing applications.
• Research and development: Supports development of improved wood products and composites by providing baseline mechanical property tests.

Related Standards

• EN 12509: Specifies requirements for poles made of round timber; EN 14251 excludes timber covered by this standard.
• EN 338: Structural timber - Strength classes; related to grading wood for structural use.
• EN 384: Determination of characteristic values of mechanical properties and density; complements test data for design strength values.
• EN 1912: Structural timber - Strength classes and assignment of species; helps classify timber tested under EN 14251.
• ISO and ASTM standards: Other international standards specify additional testing or grading methods for wood products, providing cross-references to EN 14251 for harmonized application.

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Keywords: EN 14251:2003, structural round timber, test methods, bending strength, modulus of elasticity, compressive strength, timber testing standard, debarked round timber, moisture content determination, timber density test, timber mechanical properties, CEN timber standards, European timber testing, timber structural design

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Okrogli konstrukcijski les – Preskusne metodeRundholz für tragende Zwecke - PrüfverfahrenBois de structure rond - Méthodes d'essaiStructural round timber - Test methods91.080.20Lesene konstrukcijeTimber structures79.040Les, hlodovina in žagan lesWood, sawlogs and sawn timberICS:Ta slovenski standard je istoveten z:EN 14251:2003SIST EN 14251:2004en01-september-2004SIST EN 14251:2004SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14251December 2003ICS 79.040; 91.080.20English versionStructural round timber - Test methodsBois de structure rond - Méthodes d'essaiRundholz für bauliche Zwecke - PrüfverfahrenThis European Standard was approved by CEN on 1 September 2003.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and UnitedKingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2003 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14251:2003: ESIST EN 14251:2004

nominal diameter of round timber beam at either end grain face, in millimetresdh diameter of round timber perpendicular to the direction of load at mid span, in millimetresdvdiameter of round timber in the direction of load at mid span, in millimetresEm,0 modulus of elasticity in bending, in Newton per square millimetreEc,0 modulus of elasticity in compression parallel to the grain, in Newton per square millimetreFload, in NewtonFmax maximum load, in Newtonfc,0 compressive strength parallel to the grain, in Newton per square millimetrefm,0 bending strength, in Newton per square millimetreh height of compression parallel to grain test piece, in millimetresh0gauge length of compression parallel to grain test piece, in millimetresI second moment of area, in millimetres to the fourth powerl
span in bending, in millimetresl1 gauge length for the determination of modulus of elasticity in bending, in millimetresw deflection or displacement in compression, in millimetres.5 Determination of the moisture content of test piecesThe tests shall be carried out on pieces which are conditioned at
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