1、BRITISH STANDARD BS EN 595:1995 Timber structures Test methods Test of trusses for the determination of strength and deformation behaviour The European Standard EN595:1995 has the status of a British StandardBSEN595:1995 This British Standard, having been prepared under the directionof the Sector Bo
2、ard for Building and Civil Engineering, was published under the authorityof the Standards Boardand comes into effect on 15 October1995 BSI08-1999 The following BSI references relate to the work on this standard: Committee reference B/518/1 Draft for comment91/18867DC ISBN 0 580 24614 0 Committees re
3、sponsible 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 Agrment) Department of
4、the Environment (Building Research Establishment) Institution of Civil Engineers Institution of Structural Engineers Timber Research and Development Association Wood Panel Products Federation Coopted members Amendments issued since publication Amd. No. Date CommentsBSEN595:1995 BSI 08-1999 i Content
5、s Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN595 3BSEN595:1995 ii BSI 08-1999 National foreword This British Standard has been prepared by Subcommittee B/518/1 and is the English language version of EN595:1995 Timber structures Test methods Test of truss
6、es for the determination of strength and deformation behaviour published by the European Committee for Standardization (CEN). This British Standard supersedes clauses32 to38 and clause40 of BS5268:1985 Structural use of timber Part3. Code of practice for trussed rafter roofs. These are in the proces
7、s of being withdrawn by revision of BS5268 1) . 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 obliga
8、tions. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN title page, pages2 to5 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
9、 front cover. 1) In preparation.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN595 March1995 ICS91.040.00 Descriptors: Timber construction, mechanicaltests, stiffness tests, determination, mechanical strength English version Timber structures Test methods Test of trusses for thedetermination of
10、 strength and deformation behaviour Structures en bois Mthodes dessai Essais des fermes pour la dtermination de la rsistance et de la rigidit Holzbauwerke Prfverfahren Prfung von Fachwerktrgern zur Bestimmung der Tragfhigkeit und des Verformungverhaltens This European Standard was approved by CEN on
11、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 o
12、btained 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 S
13、ecretariat 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 Commi
14、ttee for Standardization Comit Europen de Normalisation Europisches Komitee fr 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. EN595:1995EEN595:1
15、995 BSI 08-1999 2 Foreword This European Standard has been prepared by the Technical Committee CEN/TC124, Timber structures, of which the secretariat is held by DS. NOTEIt is considered desirable to maintain the same clause numbers consistently throughout this series of standards. Consequently, some
16、 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 September199
17、5, and conflicting national standards shall be withdrawn at the latest by September1995. 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, Lux
18、embourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Symbols 3 5 Requirements 3 6 Test methods 3 6.1 Principle 3 6.2 Apparatus 3 6.3 Preparation of test pieces 3 6.4 Procedure 3 6.5 Result
19、s 5 6.6 Test report 5 Figure 1 Loading procedures 4EN595:1995 BSI 08-1999 3 1 Scope This standard specifies the test procedures for determining the strength and deformation behaviour of trusses. NOTEThe test methods are based on EN380. 2 Normative references None. 3 Definitions None. 4 Symbols 5 Req
20、uirements None. 6 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. 6.2 Apparatus 6.2
21、.1 General 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. 6.2.2 Lateral restraint Lateral restraint shall not affect the ve
22、rtical 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 3% of the load applied, or, for loads of less than0,1F max , with an accuracy of 0,3% F max . The deformations shall be measured
23、 to the nearest0,1mm in the deformation test; and to the nearest1mm in the strength test. Deformations shall be measured at all points considered important to the serviceability requirements of the truss. 6.3 Preparation of the test pieces The tests shall normally be carried out on trusses which hav
24、e 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
25、 of the trusses shall be determined. 6.4 Procedure 6.4.1 General The loading procedures are shown diagrammatically in Figure 1. The test loads shall be applied at a constant rate of movement at each loading point, avoiding impact or dynamic effects. A loading rate of0,25 Q per minute shall be used u
26、nless otherwise stated below. 6.4.2 Initial loading The initial loading procedure consists of applying the following loading regime to the truss. a) Only G 1acting and F =0. Read deformation transducers. b) Apply F = G 2 . Measure deformations. c) Maintain F = G 2for a period of at least1800s. Measu
27、re deformations. d) Remove F. Measure deformations. e) Allow T r =900s. Measure deformations. 6.4.3 Load test 6.4.3.1 General This test procedure is in two parts: deformation test (see6.4.3.2), and24h test (see6.4.3.3), where both are performed immediately after the initial loading procedure. F appl
28、ied load (in N) F max maximum applied load (in N) G characteristic permanent load composed of G 1and G 2(in N) G 1 self-weight of truss (in N) G 2 applied permanent load (in N) Q characteristic value of variable load (in N) T loading time (in s) T r recovery time (in s)EN595:1995 4 BSI 08-1999 6.4.3
29、.2 Deformation test The procedure consists of applying the following loading regime to the truss: f) Re-apply F = G 2 . Measure deformations. g) Maintain F = G 2for a period of900s. Measure deformations. h) Apply F = G 2 + Q where T is between1800s and2400s. Measure deformations. i) Maintain F = G 2
30、 + Q for a period of3600s. Measure deformations after T=900s,1800s,2700s and3600s. j) Release F = G 2 + Q. Measure deformations immediately and after T rof900s. The remaining part of the test is then initiated and completed over a period of24h. 6.4.3.3 24h test The procedure consists of applying the
31、 following loading regime to the truss. NOTEThe test procedure provides information on the rate of change of deformation, over24h, of the truss when subject to characteristic permanent and variable load. k) Re-apply F = G 2 + Q. Measure deformations immediately and after T =900s. l) Maintain F for a
32、 period of24h. Measure deformations at sufficient intervals to allow a time/deflection curve to be plotted and at the end of the24h period. m) Measure deformations. n) Release F = G 2 + Q. Measure deformations immediately and after T rof900s. 6.4.4 Strength test The procedure consists of applying th
33、e following loading regime to the truss. NOTEThe test procedure provides information on the maximum load capacity of the truss. o) Re-apply F = G 2 + Q. Measure deformations. p) Maintain F = G 2 + Q for a period of900s. q) Increase F at a rate not greater than a load of0,25 Q per minute, or a deform
34、ation of(0,0005+span) per minute until F maxis reached. Record F max . Figure 1 Loading proceduresEN595:1995 BSI 08-1999 5 r) Determine moisture content at the point of failure. The maximum load F maxon a truss may be assumed to have been reached when fracture of a truss member occurs, or joint fail
35、ure 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 F max . 6.6 Test report The test report shall include the following information: a) sampling
36、 procedure; b) details of the sizes and configuration of the truss members; c) values of G 1 , G 2and Q; 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 (includ
37、ing 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
38、 deformations at all measurement positions; j) value of F max ; 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
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