00560933 PDF BRITISH STANDARD BS EN 595 1995 Timber structures — Test methods — Test of trusses for the determination of strength and deformation behaviour The European Standard EN 595 1995 has the st[.]
BRITISH STANDARD Timber structures — Test methods — Test of trusses for the determination of strength and deformation behaviour The European Standard EN 595:1995 has the status of a British Standard BS EN 595:1995 BS EN 595:1995 Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/518, Structural timber, to Subcommittee B/518/1, Test methods, upon which the following bodies were represented: Department of the Environment (British Board of Agrément) Department of the Environment (Building Research Establishment) Institution of Civil Engineers Institution of Structural Engineers Timber Research and Development Association Wood Panel Products Federation Coopted members This British Standard, having been prepared under the direction of the Sector Board for Building and Civil Engineering, was published under the authority of the Standards Board and comes into effect on 15 October 1995 © BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference B/518/1 Draft for comment 91/18867 DC ISBN 580 24614 Amendments issued since publication Amd No Date Comments BS EN 595:1995 Contents Committees responsible National foreword Foreword Text of EN 595 © BSI 08-1999 Page Inside front cover ii i BS EN 595:1995 National foreword This British Standard has been prepared by Subcommittee B/518/1 and is the English language version of EN 595:1995 Timber structures — Test methods — Test of trusses for the determination of strength and deformation behaviour published by the European Committee for Standardization (CEN) This British Standard supersedes clauses 32 to 38 and clause 40 of BS 5268:1985 Structural use of timber — Part Code of practice for trussed rafter roofs These are in the process of being withdrawn by revision of BS 52681) A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages to and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover 1) In ii preparation © BSI 08-1999 EUROPEAN STANDARD EN 595 NORME EUROPÉENNE March 1995 EUROPÄISCHE NORM ICS 91.040.00 Descriptors: Timber construction, mechanical tests, stiffness tests, determination, mechanical strength English version Timber structures — Test methods — Test of trusses for the determination of strength and deformation behaviour Structures en bois — Méthodes d’essai — Essais des fermes pour la détermination de la résistance et de la rigidité Holzbauwerke — Prüfverfahren — Prüfung von Fachwerkträgern zur Bestimmung der Tragfähigkeit und des Verformungverhaltens This European Standard was approved by CEN on 1994-12-05 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 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 translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1995 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and its members Ref No EN 595:1995 E EN 595:1995 Foreword This European Standard has been prepared by the Technical Committee CEN/TC 124, Timber structures, of which the secretariat is held by DS NOTE It is considered desirable to maintain the same clause numbers consistently throughout this series of standards Consequently, some clauses are void in this edition of this standard, but it is envisaged that future editions may need to include text in these clauses 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 September 1995, and conflicting national standards shall be withdrawn at the latest by September 1995 According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom Contents Foreword Scope Normative references Definitions Symbols Requirements Test methods 6.1 Principle 6.2 Apparatus 6.3 Preparation of test pieces 6.4 Procedure 6.5 Results 6.6 Test report Figure — Loading procedures Page 3 3 3 3 3 5 © BSI 08-1999 EN 595:1995 Scope Normative references The deformations shall be measured — to the nearest 0,1 mm in the deformation test; and — to the nearest mm in the strength test Deformations shall be measured at all points considered important to the serviceability requirements of the truss None 6.3 Preparation of the test pieces Definitions The tests shall normally be carried out on trusses which have been conditioned at the standard environment of (20 ± 2) °C and (65 ± 5) % relative humidity, but when other conditions apply, they shall be reported The test laboratory shall normally be maintained at the standard environment, but when other conditions apply, they shall be reported The moisture content of the trusses shall be determined This standard specifies the test procedures for determining the strength and deformation behaviour of trusses NOTE The test methods are based on EN 380 None Symbols F Fmax applied load (in N) maximum applied load (in N) G characteristic permanent load composed of G1 and G2 (in N) G1 self-weight of truss (in N) G2 applied permanent load (in N) Q T Tr characteristic value of variable load (in N) loading time (in s) recovery time (in s) Requirements None 6.4 Procedure 6.4.1 General The loading procedures are shown diagrammatically in Figure The test loads shall be applied at a constant rate of movement at each loading point, avoiding impact or dynamic effects A loading rate of 0,25 Q per minute shall be used unless otherwise stated below 6.4.2 Initial loading 6.2 Apparatus The initial loading procedure consists of applying the following loading regime to the truss a) Only G1 acting and F = Read deformation transducers b) Apply F = G2 Measure deformations c) Maintain F = G2 for a period of at least 800 s Measure deformations d) Remove F Measure deformations e) Allow Tr = 900 s Measure deformations 6.2.1 General 6.4.3 Load test The apparatus used for the test shall simulate the assumed or actual service conditions of the truss in respect of the truss span, the size, position and rigidity of the truss bearing and the lateral stability of the truss 6.4.3.1 General Test methods 6.1 Principle The purpose of the test methods is to measure the deformation behaviour and strength of trusses subjected to the type of loading which may be expected in service Uniformly distributed test loads may be simulated by applying point loads This test procedure is in two parts: deformation test (see 6.4.3.2), and 24 h test (see 6.4.3.3), where both are performed immediately after the initial loading procedure 6.2.2 Lateral restraint Lateral restraint shall not affect the vertical stiffness of the truss 6.2.3 Load and deformation measurement The apparatus shall be capable of continuously applying and recording the loads F with an accuracy of ± % of the load applied, or, for loads of less than 0,1 Fmax, with an accuracy of ± 0,3 % Fmax © BSI 08-1999 EN 595:1995 Figure — Loading procedures 6.4.3.2 Deformation test The procedure consists of applying the following loading regime to the truss: f) Re-apply F = G2 Measure deformations g) Maintain F = G2 for a period of 900 s Measure deformations h) Apply F = G2 + Q where T is between 800 s and 400 s Measure deformations i) Maintain F = G2 + Q for a period of 600 s Measure deformations after T = 900 s, 800 s, 700 s and 600 s j) Release F = G2 + Q Measure deformations immediately and after Tr of 900 s The remaining part of the test is then initiated and completed over a period of 24 h 6.4.3.3 24 h test The procedure consists of applying the following loading regime to the truss NOTE The test procedure provides information on the rate of change of deformation, over 24 h, of the truss when subject to characteristic permanent and variable load k) Re-apply F = G2 + Q Measure deformations immediately and after T = 900 s l) Maintain F for a period of 24 h Measure deformations at sufficient intervals to allow a time/deflection curve to be plotted and at the end of the 24 h period m) Measure deformations n) Release F = G2 + Q Measure deformations immediately and after Tr of 900 s 6.4.4 Strength test The procedure consists of applying the following loading regime to the truss NOTE The test procedure provides information on the maximum load capacity of the truss o) Re-apply F = G2 + Q Measure deformations p) Maintain F = G2 + Q for a period of 900 s q) Increase F at a rate not greater than — a load of 0,25 Q per minute, or — a deformation of (0,0005 + span) per minute until Fmax is reached Record Fmax © BSI 08-1999 EN 595:1995 r) Determine moisture content at the point of failure The maximum load Fmax on a truss may be assumed to have been reached when — fracture of a truss member occurs, or — joint failure occurs, or — substantial deformation continues without a further increase in load 6.5 Results The test results shall contain the load and deformation readings measured during the test and the maximum load Fmax 6.6 Test report The test report shall include the following information: a) sampling procedure; b) details of the sizes and configuration of the truss members; c) values of G1, G2 and Q; © BSI 08-1999 d) conditioning and test laboratory environment; e) specification and quality of material used in the manufacture, with a note of any defects; f) specification of the mechanical fasteners (including corrosion protection), and their quantity and positioning; g) description of the bearings and lateral truss support in the test rig; h) description of the method of loading the truss and of measuring the truss deformations; i) test loads sustained during the tests together with the corresponding deformations at all measurement positions; j) value of Fmax; k) type and position of failure; l) moisture content at the point of failure Attention shall also be drawn to any observed defect in design or fabrication which may lead in time to abnormal reduction in the strength of the truss BS EN 595:1995 BSI — British Standards Institution BSI is the independent national body responsible for preparing British Standards It presents the UK view on standards in Europe and at the international level It is incorporated by Royal Charter Revisions British Standards are updated by amendment or revision Users of British Standards should make sure that they possess the latest amendments or editions It is the constant aim of BSI to improve the quality of our products and services We would be grateful if anyone finding an inaccuracy or ambiguity while using 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