Wood-based panels - Determination of duration of load and creep factors

This European Standard specifies a method of determining in a constant climate both a duration of load factor and a creep factor for wood-based panels stressed in flatwise bending with and without a shear component. Details of an alternative but provisional method employing medium sized test pieces are given in Annex A; this method can also be used for test pieces loaded under varying climates.
NOTE   The duration of load factor is necessary to modify the characteristic strength values obtained in short-term structural tests in order to derive long-term values. The creep factor obtained in the test is used to predict a long-term deflection from the initial elastic deflection.

Holzwerkstoffe - Bestimmung von Zeitstandfestigkeit und Kriechzahl

Diese Europäische Norm legt ein Verfahren zur Bestimmung der Zeitstandfestigkeit und der Kriechzahl von Holzwerkstoffen im Flachbiegeversuch mit und ohne Schubkomponente im Konstantklima fest. Einzelheiten zu einem alternativen aber vorläufigen Verfahren unter Verwendung von mittelgroßen Prüfkörpern sind im Anhang A aufgeführt, dieses Verfahren kann auch für Prüfkörper verwendet werden, die unter wechselnden Klimabedingungen belastet sind.
ANMERKUNG   Die Kenntnis der Zeitstandfestigkeit ist notwendig, um die in Kurzzeitprüfungen gewonnenen charakteristischen Werte zu modifizieren und dadurch Langzeit-Werte zu erhalten. Die in der Prüfung ermittelte Kriechzahl dient der Ableitung einer Langzeit-Verformung aus der elastischen Ausgangsverformung.

Panneaux à base de bois - Détermination des facteurs de durée de charge et de fluage

La présente Norme européenne spécifie une méthode de détermination dans un climat constant, du facteur de durée de charge et du facteur de fluage pour les panneaux à base bois en flexion à plat avec et sans composante de cisaillement. Des détails sur une autre méthode provisoire employant des éprouvettes en semi-grandeur sont donnés dans l'Annexe A ; cette méthode peut aussi être utilisée pour des éprouvettes sous contrainte dans des climats variables.
NOTE   Le facteur de durée de charge est nécessaire pour modifier les valeurs caractéristiques de résistance obtenues dans les essais de courte durée pour les usages en structure afin d'obtenir des valeurs pour les longues durées. Le facteur de fluage obtenu dans l'essai est utilisé pour estimer une flèche pour des longues durées à partir de la flèche élastique initiale.

Lesne plošče - Ugotavljanje faktorjev trajanja obremenitve in lezenja

Ta evropski standard določa metodo za ugotavljanje faktorjev trajanja obremenitve in lezenja pri konstantnih okoljskih pogojih za lesne plošče z upogibno obremenitvijo na površini s strižno komponento in brez nje. V dodatku B so podane podrobnosti o alternativni, vendar začasni metodi, ki zajema srednje velike preskusne dele; ta metoda se lahko uporablja tudi za preskusne dele v različnih okoljskih pogojih.

General Information

Status
Published
Publication Date
16-Apr-2013
Current Stage
9093 - Decision to confirm - Review Enquiry
Due Date
02-Dec-2018
Completion Date
16-May-2019

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.HQMDHolzwerkstoffe - Bestimmung von Zeitstandfestigkeit und KriechzahlPanneaux à base de bois - Détermination des facteurs de durée de charge et de fluageWood-based panels - Determination of duration of load and creep factors79.060.01Wood-based panels in generalICS:Ta slovenski standard je istoveten z:EN 1156:2013SIST EN 1156:2013en,fr,de01-oktober-2013SIST EN 1156:2013SLOVENSKI

STANDARDSIST ENV 1156:20001DGRPHãþD
SIST EN 1156:2013
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 1156
April 2013 ICS 79.060.01 Supersedes ENV 1156:1998English Version
Wood-based panels - Determination of duration of load and creep factors

Panneaux à base de bois - Détermination des facteurs de durée de charge et de fluage

Holzwerkstoffe - Bestimmung von Zeitstandfestigkeit und Kriechzahl This European Standard was approved by CEN on 1 March 2013.

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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,

B-1000 Brussels © 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1156:2013: ESIST EN 1156:2013

EN 1156:2013 (E) 2 Contents Page Foreword ....................................................................................................................................................... 3 1 Scope ................................................................................................................................................ 4 2 Normative references ....................................................................................................................... 4 3 Principle............................................................................................................................................ 4 4 Apparatus ......................................................................................................................................... 4 5 Sampling of panels and preparation of test pieces ........................................................................ 7 5.1 Sampling and cutting ....................................................................................................................... 7 5.2 Dimensions of test pieces ............................................................................................................... 7 5.3 Conditioning ..................................................................................................................................... 7 6 Procedure ......................................................................................................................................... 8 6.1 Measurement of dimensions ........................................................................................................... 8 6.2 Setting up the test rigs with test pieces .......................................................................................... 8 6.3 Determination of short-term bending strength ............................................................................... 8 6.4 Determination of the duration of load and creep factors ............................................................... 8 6.4.1 General testing required .................................................................................................................. 8 6.4.2 Testing for duration of load ............................................................................................................. 9 6.4.3 Testing for creep .............................................................................................................................. 9 7 Expression of results ..................................................................................................................... 10 7.1 Duration of load factor ................................................................................................................... 10 7.2 Creep factor .................................................................................................................................... 11 8 Test report ...................................................................................................................................... 13 Annex A (informative)

Provisional test method for medium-size test pieces ........................................... 14 A.1 General ........................................................................................................................................... 14 A.2 Principle.......................................................................................................................................... 14 A.3 Apparatus ....................................................................................................................................... 14 A.4 Sampling of panels and the preparation of test pieces ................................................................ 15 A.5 Procedure ....................................................................................................................................... 15 A.6 Expression of results ..................................................................................................................... 15 A.7 Test report ...................................................................................................................................... 15 Bibliography................................................................................................................................................ 16

SIST EN 1156:2013

EN 1156:2013 (E) 3 Foreword This document (EN 1156:2013) has been prepared by Technical Committee CEN/TC 112 “Wood-based panels”, the secretariat of which is held by DIN. 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 2013, and conflicting national standards shall be withdrawn at the latest by October 2013. 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 ENV 1156:1998. Compared to ENV 1156:1998, the following significant technical modifications have been made: a) status changed from ENV to EN; b) accuracy of the deflection measurement changed from 0,001 mm to 0,01 mm. 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 1156:2013

EN 1156:2013 (E) 4 1 Scope This European Standard specifies a method of determining in a constant climate both a duration of load factor and a creep factor for wood-based panels stressed in flatwise bending with and without a shear component. Details of an alternative but provisional method employing medium sized test pieces are given in Annex A; this method can also be used for test pieces loaded under varying climates. NOTE The duration of load factor is necessary to modify the characteristic strength values obtained in short-term structural tests in order to derive long-term values. The creep factor obtained in the test is used to predict a long-term deflection from the initial elastic deflection. 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 310, Wood-based panel EN 325, Wood- EN 326-1, Wood- 1: pampling and cutting of test pieces and expression of test results EN 1058, Wood--percentile values and characteristic mean values EN 1995-1-1, Eurocode

1-buildings 3 Principle Determination in a constant climate of the load duration factor (loss in strength with time under load) and the creep factor (ratio of increase in deflection with time to the initial elastic deflection) in bending by applying and sustaining a constant moment over the central region of a test piece; both the time to failure, and the increase in deflection with time are measured. 4 Apparatus 4.1 Measuring instruments as specified in EN 325. 4.2 A number of test rigs (see Figure 1), that have essentially the following components: 4.2.1 Two parallel cylindrical supports of a length exceeding the width of the test piece and of diameter d = (15 ± 0,5) mm.

The distance between the supports shall be adjustable, and each support shall be capable of rotating in its frame. Two cylindrical loading rollers of the same length and diameter as the supports. These shall lie parallel to the supports, be capable of rotating, and be linked together with cross-arms of fixed length. SIST EN 1156:2013

EN 1156:2013 (E) 5 The distance l1 between the loading rollers shall be 150 mm, the distance between one support and the nearer loading roller shall be five times the nominal thickness t of the test piece. The horizontal and vertical components of the loading cradle shall be rigidly connected. NOTE 1 For boards with a low bending stiffness large deflections can occur. In general, the test configuration described here is suitable for a test piece with a stiffness (EmI) greater than 9 000 kNmm2; test pieces with a lower stiffness can be tested by proportionately reducing the distances between the rollers (l1+2 l2) as well as the distance between the deflection measuring points. NOTE 2 The load can be applied to the cross-arms through some form of mechanical advantage. Dimensions in millimetres

Key F dead-load l1 = 150 t thickness l2 = 5 t
L = l1+10 t+60

d = 15 ± 0,5 Figure 1 — Test arrangement for applying load for static bending and creep tests with test piece in position 4.2.2 A suitable instrument for measuring the deflection of the test piece in the middle of the span which is graduated to allow a reading to 0,01 mm or better and which enables readings of the displacement at the centre of the upper surface of the test piece to be taken in relation to two points on the upper surface of the test piece each 60 mm from the transverse centre line (see Figure 2).

This general method will measure creep in bending free of any influence of shear (method 1). SIST EN 1156:2013

EN 1156:2013 (E) 6 Dimensions in millimetres

Key F dead-load Figure 2 — Method 1 (general method) for the measurement of deflection Where it is desired to measure creep in bending both with and without a shear component a measuring system as illustrated in Figure 3 shall be used (method 2). Dimensions in millimetres

Key F dead-load Figure 3 — Method 2 for the measurement of deflection with and without a shear component 4.3 An arrangement for testing the short-term bending strength with the same loading configuration to the creep test arrangement. 4.4 Weights (= dead load) for applying different constant loads (forces) on the test pieces. 4.5 A controlled environment room capable of maintaining a fixed temperature to ±1 °C and a fixed relative humidity to ± 3 %. 4.6 Equipment for recording temperature and relative humidity. SIST EN 1156:2013

EN 1156:2013 (E) 7 5 Sampling of panels and preparation of test pieces 5.1 Sampling and cutting Panels shall be sampled from production sites in accordance with EN 1058. Where previous static bending tests have indicated that the differences between the means of strength or modulus of elasticity in the two directions of the panel, i.e. longitudinal and transverse, is equal to, or less than 15 %, then a single set of test pieces may be used, provided that these are orientated in the direction of the lower values of strength and elasticity. Where these tests have indicated differences greater than 15 % in strength or modulus in the two directions, then two sets of test pieces shall be used. However, if the end-use direction of span is known, then it is only necessary to carry out tests in that direction. Where there is no available information on the relative strength and modulus in the longitudinal and transverse directions, then this shall be determined prior to the start of creep testing. Test pieces from the two directions shall be removed and tested according to EN 310. For creep, and load-duration tests, each set of test pieces shall comprise 70 pairs of side-matched test pieces cut in a manner that ensures that all panels and test pieces are sampled as equally as possible. This number of samples is based on the assumption that at low stress levels the material is behaving in a linear viscoelastic mode. However, if there is doubt about this assumption, then creep tests should be carried out at more than one stress level as recommended in 6.4.3, and this will necessitate additional test pieces equivalent to an extra 10 for each additional stress level. Test pieces shall be free of visible strength-reducing characteristics. Test pieces containing visible strength-reducing characteristics and of a larger size may be tested according to the provisional test method given in Annex A. 5.2 Dimensions of test pieces The test pieces shall be rectangular, and of the following dimensions: The width shall be (50 ± 0,5) mm. For test pieces having a stiffness (Em I) greater than 9 000 kNmm2 the length L shall be 10 times the nominal thickness plus 210 mm, with a maximum length of 1 200 mm. For test pieces having a stiffness (Em I) of 9 000 kNmm2 or less, the length of test piece may be reduced according to NOTE 1 of 4.2.1. 5.3 Conditioning Before testing, the test pieces shall be conditioned to constant mass in an atmosphere corresponding to the most severe conditions in each of the service classes (SC) according to EN 1995-1-1 to which the appropriate characteristic values apply: these are 20 °C/65 % relative humidity for SC1, 20 °C/85 % relative humidity for SC2, and 20 °C/95 % relative humidity for SC3 (for tolerances see 4.5). Constant mass is considered to be reached when the results of two successive weighing operations, carried out at an interval of 24 h, do not differ by more than 0,1 % of the mass of the test piece. SIST EN 1156:2013

EN 1156:2013 (E) 8 6 Procedure 6.1 Measurement of dimensions Measure the width and thickness o

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