Bsi bs en 00595 1995 (1999)

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[.]

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

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 0 580 24614 0

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

Amendments issued since publication

Amd No Date Comments

© BSI 08-1999 i

Contents

Page

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 3 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are in the process of being withdrawn by revision of BS 52681)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 2 to 5 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 preparation.

EUROPÄISCHE NORM March 1995

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

© BSI 08-1999 2

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

Page

6.3 Preparation of test pieces 3

Figure 1 — Loading procedures 4

© BSI 08-1999 3

1 Scope

This standard specifies the test procedures for

determining the strength and deformation

behaviour of trusses

NOTE The test methods are based on EN 380.

2 Normative references

None

3 Definitions

None

4 Symbols

5 Requirements

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

6.2.1 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 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 ± 3 % of the load applied, or, for loads of less

than 0,1 Fmax, with an accuracy of ± 0,3 % Fmax

The deformations shall be measured

— to the nearest 0,1 mm in the deformation test; and

— to the nearest 1 mm 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 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

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 of 0,25 Q per minute shall be used

unless otherwise stated below

6.4.2 Initial loading

The initial loading procedure consists of applying the following loading regime to the truss

a) Only G1 acting and F = 0 Read deformation

transducers

b) Apply F = G2 Measure deformations

c) Maintain F = G2 for a period of at least 1 800 s Measure deformations

d) Remove F Measure deformations.

e) Allow Tr= 900 s Measure deformations.

6.4.3 Load test

6.4.3.1 General

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

F applied load (in N)

Fmax 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 characteristic value of variable load (in N)

T loading time (in s)

Tr recovery time (in s)

EN 595:1995

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 1 800 s

and 2 400 s Measure deformations

i) Maintain F = G2+ Q for a period of 3 600 s

Measure deformations after

T = 900 s, 1 800 s, 2 700 s and 3 600 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

Figure 1 — Loading procedures

© BSI 08-1999 5

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;

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

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