1、BS ISO14347:2008ICS 25.160.40NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDFatigue Designprocedure for weldedhollow-section joints RecommendationsThis British Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 31 December2
2、008 BSI 2008ISBN 978 0 580 53490 4Amendments/corrigenda issued since publicationDate CommentsBS ISO 14347:2008National forewordThis British Standard is the UK implementation of ISO 14347:2008.The UK participation in its preparation was entrusted to TechnicalCommittee WEE/37, Acceptance levels for fl
3、aws in welds.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer imm
4、unityfrom legal obligations.BS ISO 14347:2008Reference numberISO 14347:2008(E)ISO 2008INTERNATIONAL STANDARD ISO14347First edition2008-12-01Fatigue Design procedure for welded hollow-section joints Recommendations Fatigue Procdure de dimensionnement la fatigue des assemblages souds de profils creux
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8、tral Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2008 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permissio
9、n in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedB
10、S ISO 14347:2008ISO 14347:2008(E) ISO 2008 All rights reserved iiiContents Page Foreword iv 1 Scope1 1.1 General .1 1.2 Materials .1 1.3 Types of joints .1 2 Normative references1 3 Terms and definitions .2 4 Symbols and abbreviated terms 7 5 Cumulative fatigue damage12 6 Partial safety factor .12 7
11、 Fatigue design procedures.12 7.1 Hot-spot stress method 12 7.2 Design procedures 13 8 Fatigue strength 13 8.1 Member forces .13 8.2 Nominal stress ranges14 8.3 SCF calculations14 8.4 Hot-spot stress ranges .14 8.5 Fatigue strength curves15 9 SCF calculations for CHS joints 17 9.1 Uniplanar CHS T- a
12、nd Y-joints .17 9.2 Uniplanar CHS X-joints .18 9.3 Uniplanar CHS K-joints with gap .18 9.4 Multiplanar CHS XX-joints 19 9.5 Multiplanar CHS KK-joints with gap20 9.6 Minimum SCF values 21 10 SCF calculations for RHS joints 21 10.1 Uniplanar RHS T- and X-joints .21 10.2 Uniplanar RHS K-joints with gap
13、 .22 10.3 Uniplanar RHS K-joints with overlap.23 10.4 Multiplanar RHS KK-joints with gap24 10.5 Minimum SCF values 25 Annex A (normative) Quality requirements for hollow sections26 Annex B (normative) Weld details.27 Annex C (informative) A fatigue assessment procedure 29 Annex D (normative) SCF equ
14、ations and graphs for CHS joints.31 Annex E (normative) SCF equations and graphs for RHS joints .47 Bibliography67 BS ISO 14347:2008ISO 14347:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodie
15、s (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations,
16、 governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO
17、/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the m
18、ember bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 14347 was prepared by the International Institute of Welding, Commis
19、sion XV, Design, analysis and fabrication of welded structures, recognized as an international standardizing body in the field of welding in accordance with Council Resolution 42/1999. Requests for official interpretations of any aspect of this International Standard should be directed to the ISO Ce
20、ntral Secretariat, who will forward them to the IIW Secretariat for an official response. BS ISO 14347:2008INTERNATIONAL STANDARD ISO 14347:2008(E) ISO 2008 All rights reserved 1Fatigue Design procedure for welded hollow-section joints Recommendations 1 Scope 1.1 General This International Standard
21、gives recommendations for the design and analysis of unstiffened, welded, nodal joints in braced structures composed of hollow sections of circular or square shape (with or without rectangular chord) under fatigue loading. This International Standard applies to structures: a) fulfilling quality requ
22、irements for hollow sections (see Annex A); b) complying with recommended weld details (see Annex B); c) employing permitted steel grades (see 1.2); d) having hollow section joints (see 1.3); e) having either 1) square or rectangular hollow sections with a thickness between 4 mm and 16 mm, or 2) cir
23、cular hollow sections with a thickness between 4 mm and 50 mm; f) having as stress range the range of “hot-spot” stress; g) having identical brace (branch) members. 1.2 Materials This International Standard applies to both hot-finished and cold-formed steel structural hollow sections, complying with
24、 the applicable national manufacturing specification, that fulfil specified quality requirements (see Annex A). 1.3 Types of joints This International Standard applies to joints consisting of circular hollow sections (CHS) or rectangular hollow sections (RHS) as used in uniplanar or multiplanar trus
25、ses or girders, such as T-, Y-, X-, K-, XX-, and KK-joints (see Figure 1 and Figure 2). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition o
26、f the referenced document (including any amendments) applies. ISO 630:1995, Structural steels Plates, wide flats, bars, sections and profiles BS ISO 14347:2008ISO 14347:2008(E) 2 ISO 2008 All rights reserveda) CHS T-joints b) CHS Y-joints c) CHS X-joints d) CHS K-joints with gap e) RHS T-joints f) R
27、HS X-joints g) RHS K-joints with gap h) RHS K-joints with overlap NOTE RHS are assumed to be square, although this International Standard is likely to be applicable to rectangularchord members, welded to square branch members. Figure 1 Types of uniplanar joints covered by this International Standard
28、 a) CHS XX-joints b) CHS KK-joints with gap c) RHS KK-joints with gap NOTE RHS are assumed to be square, although this International Standard is likely to be applicable to rectangularchord members, welded to square branch members. Figure 2 Types of multiplanar joints covered by this International St
29、andard 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 brace branch welded hollow section joints cut and welded member See Figure 3. BS ISO 14347:2008ISO 14347:2008(E) ISO 2008 All rights reserved 3Key 1 load applied in the branch 2 crown poi
30、nt 3 branch 4 saddle point 5 weld 6 chord a) Joint nomenclature Key 1 chord wall 2 stress increase due to weld geometry 3 brace hot-spot stress 4 weld toe 5 extrapolation of geometric stress distribution to weld toe 6 stress in branch 7 nominal stress 8 increase in stress due to overall joint geomet
31、ry 9 branch wall 10 weld b) Stress distribution in branch Figure 3 Hot-spot stress definition in nodal joints BS ISO 14347:2008ISO 14347:2008(E) 4 ISO 2008 All rights reservedKey 1 chord wall 2 stress increase due to weld geometry 3 chord hot-spot stress 4 weld toe 5 extrapolation of geometric stres
32、s distribution to weld toe 6 stress in chord 7 nominal stress 8 increase in stress due to overall joint geometry 9 branch wall c) Stress distribution in chord Figure 3 (continued) 3.2 constant amplitude fatigue limit welded hollow section joints stress range for a specific S-N curve when the number
33、of cycles, N, is 5 million or greater 3.3 cut-off limit stress range for a specific S-N curve when the number of cycles, N, is 100 million or greater, used in the assessment of fatigue under variable amplitude loading 3.4 fatigue deterioration of a component due to the initiation and growth of crack
34、s under fluctuating loads 3.5 fatigue life endurance Nfnumber of applied cycles to achieve a defined failure criterion ISO 1099:2006, 3.14 NOTE In this International Standard, crack growth through the wall thickness is considered as failure. 3.6 gap length g distance measured along the length of the
35、 connecting face of the chord between the toes of the adjacent brace members See Figure 4. BS ISO 14347:2008ISO 14347:2008(E) ISO 2008 All rights reserved 5Key 1 member (overlapping in the lower diagram) 2 optionally overlapped member NOTE For variable definitions, see Clause 4. Figure 4 Definition
36、of gap g and overlap q 3.7 hot-spot stress welded hollow section joints point along the weld vicinity where the extrapolated primary stress has its maximum value (i.e. the maximum geometric stress) NOTE This definition differs from the more general definition of hot-spot stress as the structural str
37、ess at the weld toe. The extrapolation is carried out from the region outside the influence of the effect on the stress of geometric discontinuities due to the joint configuration, but close enough to fall inside the zone of the stress gradient caused by the global geometrical effects of the connect
38、ion. The extrapolation is carried out on the branch or brace (cut and welded member) side and the chord (continuous member) side of each weld (see Figure 3). The hot-spot stress can be determined by considering the stress perpendicular to the weld toe for the chord and the stress parallel to the bra
39、ce axis for the brace. 3.8 nominal stress welded hollow section joints maximum stress in a cross-section calculated on the actual cross-section by simple elastic theory without taking into account the effect of geometrical discontinuities due to the joint configuration on the stress BS ISO 14347:200
40、8ISO 14347:2008(E) 6 ISO 2008 All rights reserved3.9 overlap Ov ratio of the overlap length, q, to the projected connecting length to chord of overlapping brace, p NOTE The overlap is expressed as a percentage. See Figure 4, where b1= h1= h2, t1= t2, and 1= 2. See Clause 4 for the variable definitio
41、ns. 3.10 S-N curve curve giving the relation between the stress range and the number of cycles to failure NOTE 1 Conventionally, the range of stress is plotted on the vertical axis and the number of cycles on the horizontal axis using logarithmic scales for both axes. NOTE 2 The S-N curves given in
42、this International Standard have been derived from a statistical analysis of relevant experimental data and represent lives that are less than the mean life by two standard deviations of lg N. 3.11 stress concentration factor SCF Ktwelded hollow section joints ratio between the hot-spot stress at th
43、e joint and the nominal stress in the member due to a basic member load that causes this hot-spot stress NOTE In joints with more than one branch, each branch is considered. Generally, stress concentration factors are calculated for the chord and branch. 3.12 stress range S arithmetic difference bet
44、ween the maximum and minimum stress S = Smax SminNOTE 1 Adapted from ISO 1099:2006, 3.10. NOTE 2 The nominal stress range is based on the nominal stresses while the hot-spot stress range is based on hot-spot stresses. See Figure 5. Key S tensile stress S compressive stress Figure 5 Stress range, S,
45、and stress ratio, R BS ISO 14347:2008ISO 14347:2008(E) ISO 2008 All rights reserved 73.13 stress ratio R algebraic ratio of the minimum and maximum stress of a cycle: R = Smin/SmaxISO 11782-1:1998, 3.6 NOTE Tension is taken as positive and compression as negative. See Figure 5. 3.14 structural stres
46、s geometric stress welded hollow section joints linearly distributed stress across the section thickness that arises from applied loads and the corresponding reaction of the particular structural part, taking account of all geometrical discontinuities but excluding the notch effects of local structu
47、ral discontinuities (e.g. weld toe) 4 Symbols and abbreviated terms A cross-sectional area of a member a throat thickness b0RHS chord width biwidth of brace i C chord-end fixity factor D cumulative fatigue damage index d0CHS chord diameter didiameter of brace i (CHS) e joint eccentricity Faxaxial fo
48、rce Fchforce in chord Fcovforce in carry-over brace Fifunction in determining SCF (see D.1.2, D.2.2) Frefforce of reference brace fccorrection factor fmmagnification factor fmcmultiplanar correction factor (see Tables 4 and 5) g gap length BS ISO 14347:2008ISO 14347:2008(E) 8 ISO 2008 All rights res
49、ervedg ratio of the gap length to the chord wall thickness, g/t0h0RHS chord depth hidepth of brace i Ktstress concentration factor Kt,0,b,axreference SCF for brace under basic balanced axial loading Kt,0,b4,covcarry-over SCF for brace at location 4 (see D.4.2.1.2.2) Kt,0,b4,refreference SCF for brace at location 4 (see D.4.2.1.1.2) Kt,0,ch,axreference SCF for chord under basic balanced axial loading Kt,0,ch2,covcarry-over SCF for chord at location 2 (see D.4.2.1.2.1) K
