1、 2003 by American Institute of Steel Construction, Inc. All rights reserved.This publication or any part thereof must not be reproduced in any form without permission of the publisher.Stiffening of Wule-Flange Columns at Moment Connections: Wind and Seismic Applications 13Steel Design Guide SeriesSt
2、iffening of Wide-Flange Columnsat Moment Connections:Wind and Seismic ApplicationsCharles J. Carter, PEAmerican Institute of Steel Construction, Inc.Chicago, ILAMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.Copyright 1999byAmerican Institute of Steel Construction, Inc.All rights reserved. This book o
3、r any part thereofmust not be reproduced in any form without thewritten permission of the publisher.The information presented in this publication has been prepared in accordance with rec-ognized engineering principles and is for general information only. While it is believedto be accurate, this info
4、rmation should not be used or relied upon for any specific appli-cation without competent professional examination and verification of its accuracy,suitablility, and applicability by a licensed professional engineer, designer, or architect.The publication of the material contained herein is not inte
5、nded as a representationor warranty on the part of the American Institute of Steel Construction or of any otherperson named herein, that this information is suitable for any general or particular useor of freedom from infringement of any patent or patents. Anyone making use of thisinformation assume
6、s all liability arising from such use.Caution must be exercised when relying upon other specifications and codes developedby other bodies and incorporated by reference herein since such material may be mod-ified or amended from time to time subsequent to the printing of this edition. TheInstitute be
7、ars no responsibility for such material other than to refer to it and incorporateit by reference at the time of the initial publication of this edition.Printed in the United States of AmericaRevision: October 2003 2003 by American Institute of Steel Construction, Inc. All rights reserved.This public
8、ation or any part thereof must not be reproduced in any form without permission of the publisher.1. Introduction2. Strong-Axis Moment Connectionsto Unreinforced Columns6. Design Examples3. Economical Selection of ColumnsAPPENDIX A4. Strong-Axis Moment Connections APPENDIX Bto Stiffened ColumnsAPPEND
9、IX CAPPENDIX D5. Special ConsiderationsTABLE OF CONTENTSooooooooooooooooo oooo oooooooooooooooooooooo o ooooo o oooooooo oo oooooooo. 1 5.2 C lumn Stiffening f r Weak-Axis M mentC nnecti ns 331.1 Sc pe 15.3 C lumn Stiffening f r C ncurrent Str ng- and1.2 C lumn Stiffening . 2Weak-Axis M ment C nnect
10、i ns . 341.3 References Specificati ns 25.4 Web D ubler Plates as Reinf rcement f r1.4 Definiti ns f Wind, L w-Seismic, andL cal Web Yielding, Web Crippling, and/ rHigh-Seismic Applicati ns. 2C mpressi n Buckling f the Web. 351.5 Ackn wledgements. 25.5 Web D ubler Plates at L cati ns f Weak-AxisC nn
11、ecti ns 355.6 Diag nal Stiffeners 36. 32.1 F rce Transfer in Unreinf rced C lumns 3. 392.2 Determining the Design Strength f anExample 6-1 39Unreinf rced C lumn 5Example 6-2 402.3 C lumn Cr ss-Secti nal StiffnessExample 6-3 41C nsiderati ns 11Example 6-4 452.4 Design Aids. 11Example 6-5 47. 13 Examp
12、le 6-6 473.1 Achieving Balance Between Increases Example 6-7 50in Material C st and Reducti ns in Example 6-8 52Lab rC st. 13 Example 6-9 523.2 Eliminating C lumn Stiffening 14 Example 6-10. 543.3 Minimizing the Ec n mic Impact f C lumn Example 6-11. 55Stiffening Requirements in Wind and L w- Exampl
13、e 6-12. 58Seismic Applicati ns 15 Example 6-13. 593.4 Minimizing the Ec n mic Impact f C lumn Example 6-14. 61Stiffening Requirements in High-SeismicApplicati ns 16 . 6775. 174.1 Determining the C lumn Stiffening . 83Requirements . 184.2 F rce Transfer in Stiffened C lumns 20 . 954.3 Design f Transv
14、erse Stiffeners . 22 Special C nsiderati ns. 954.4 Design f Web D ubler Plates 27 M ment C nnecti ns t C lumn Webs 99. 335.1 C lumn Stiffening f r Beams f DifferingDepth and/ r T p f Steel. 33 2003 by American Institute of Steel Construction, Inc. All rights reserved.This publication or any part the
15、reof must not be reproduced in any form without permission of the publisher.Projection of beam flanges, ortransverse stiffeners, if presentColumn panel-zone1.1 Scope1.2 Column Stiffening1Figure 1-1 Illustration of column panel-zone.Chapter 1INTRODUCTIONoo o o o ooooo o o o ooooooooooo oooooooooooooo
16、oo ooo o o oo ooo ooooooooooooooo o ooo o oooo o o ooo oo o o oooooooo ooo oooooooooooo ooooo o oooooooin Chapter 2. Ec n mical c nsiderati ns f r unreinf rcedc lumns and c lumns with reinf rcement are given inThe design f c lumns f r axial l ad, c ncurrent axial l adChapter 3. F rce transfer and de
17、sign strength f reinf rcedand flexure, and drift c nsiderati ns is well established.c lumns with str ng-axis m ment c nnecti ns, as well asH wever, the c nsiderati n f stiffening requirements f rthe design f transverse stiffeners and web d ubler plates,wide-flange c lumns at m ment c nnecti ns as a
18、r utineis c vered in Chapter 4. Special c nsiderati ns in c lumncriteri n in the selecti n f the c mp nents f the struc-stiffening, such as stiffening f r weak-axis m ment c n-tural frame is n t as well established. Thus, the ec n micnecti ns and framing arrangements with ffsets, are c v-benefit f s
19、electing c lumns with flange and web thick-ered in Chapter 5. Design examples that illustrate thenesses that d n t require stiffening is n t widely pur-applicati n f these pr visi ns are pr vided in Chapter 6,sued, in spite f the eff rts f ther auth rs wh havewith design aids f r wind and l w-seismi
20、c applicati ns inaddressed this t pic previ usly (Th rnt n, 1991; Th rn-Appendices A, B, and C.t n, 1992; Barger, 1992; Dyker, 1992; and Ricker, 1992).This Design Guide is written with the intent f changingthat trend and its c ntents are f cused in tw areas:Transverse stiffeners are used t increase
21、the strength1. The determinati n f design strength and stiffnessand/ r stiffness f the c lumn flange and/ r web at the l -f r unreinf rced wide-flange c lumns at l cati nscati n f a c ncentrated f rce, such as the flange f rce in-f str ng-axis beam-t -c lumn m ment c nnecti ns;duced by the flange r
22、flange-plate f a m ment-c nnectedand,beam. Web d ubler plates are used t increase the shear2. The design f c lumn stiffening elements, such asstrength and stiffness f the c lumn panel-z ne betweentransverse stiffeners (als kn wn as c ntinuity plates)the pair f flange f rces fr m a m ment-c nnected b
23、eam.and web d ubler plates, when the unreinf rced c l-The panel-z ne is the area f the c lumn that is b undedumn strength and/ r stiffness is inadequate.by the c lumn flanges and the pr jecti ns f the beamflanges as illustrated in Figure 1-1.Rec mmendati ns f r ec n my are included in b th cases.If
24、transverse stiffeners and/ r web d ubler plates carryF rce transfer and design strength f unreinf rcedl ads fr m members that frame t the weak-axis f thec lumns with str ng-axis m ment c nnecti ns are c vered 2003 by American Institute of Steel Construction, Inc. All rights reserved.This publication
25、 or any part thereof must not be reproduced in any form without permission of the publisher.11.3 References Specifications1.5 Acknowledgements1.4 Definitions of Wind, Low-Seismic, and High-Seismic Applications12RSpecification for StructuralSteel BuildingsSeismic Provisionsfor Structural Steel Buildi
26、ngsSpecification for StructuralSteel BuildingsAllowable Stress Design and Plastic De-signRRooo ooo o oFr m AISC Seismic Pr visi ns C mmentary Table I-C4-1, -values f8, 6, and 4 are c mm nly used f r Special M ment Frames (SMF), Inter-mediate M ment Frames (IMF), and Ordinary M ment Frames (OMF),resp
27、ectively.ooo oooooo o o oooooo oo ooo oo ooo o o o ooooooooooo o ooooooo oooooo ooooo ooooooooooooo oooooooooooo ooooooooooo oooo o oc lumn, the rec mmendati ns herein must be adjusted as High-seismic applicati ns are th se f r which inelastic be-discussed in Secti ns 5.2, 5.3, and 5.5. As discussed
28、 in havi r is expected in the beams r panel-z nes as a meansSecti n 5.4, if web d ubler plates are required t increase f dissipating the energy induced during str ng gr undthe panel-z ne shear strength, they can als be used t re- m ti ns. Such buildings are designed t meet the require-sist l cal web
29、 yielding, web crippling, and/ r c mpressi n ments in b th the LRFD Specificati n and the AISC Seis-buckling f the web per LRFD Specificati n Secti n K1. mic Pr visi ns and a resp nse m dificati n fact r thatAs discussed in Secti n 5.6, diag nal stiffening can be is appr priate f r the level f detai
30、ling required f r theused in lieu f web d ubler plates if it d es n t interfere m ment-frame system selected is used in the determina-with the weak-axis framing. ti n f seismic f rces. Additi nally, the m ment c n-necti ns used in high-seismic applicati ns have specialseismic detailing that is appr
31、priate f r the m ment-framesystem selected.This Design Guide is generally based up n the require-ments in the AISC LRFD(AISC, 1993), hereinafter referred t asthe LRFD Specificati n, and the AISCThis Design Guide resulted partially fr m w rk that was(AISC, 1997a), hereinafterd ne as part f the Design
32、 Office Pr blems activity freferred t as the AISC Seismic Pr visi ns. Alth ugh di-the ASCE C mmittee n Design f Steel Building Struc-rect reference t the AISCtures. Chapter 3 is based in large part up n this previ usw rk. Additi nally, the AISC C mmittee n Manuals and(AISC, 1989) is n t included, th
33、e principles hereinTextb ks has enhanced this Design Guide thr ugh care-remain generally applicable.ful scrutiny, discussi n, and suggesti ns f r impr vement.The auth r thanks the members f these AISC and ASCEC mmittees f r their invaluable input and guidance. Inparticular, Lawrence A. Kl iber, Jame
34、s O. Malley, andDavid T. Ricker c ntributed significantly t the devel p-F r the purp ses f this Design Guide, wind, l w-seismicment f Chapters 3 and 4 and William C. Minchin andand high-seismic applicati ns are defined as f ll ws.Th mas M. Murray pr vided helpful c mments and sug-Wind and l w-seismi
35、c applicati ns are th se f r whichgesti ns thr ugh ut the text f this Design Guide.the structure is designed t meet the requirements in theLRFD Specificati n with n special seismic detailing.This includes all applicati ns f r which the structural re-sp nse is intended t remain in the n minally elast
36、ic rangeand the resp nse m dificati n fact r used in the determi-nati n f seismic f rces, if any, is n t taken greater than 3. 2003 by American Institute of Steel Construction, Inc. All rights reserved.This publication or any part thereof must not be reproduced in any form without permission of the
37、publisher.22.1 Force Transfer in Unreinforced ColumnsH11505H11505H11505H11505H1150523PMPPdPMdP2.1.1 Required Strength for Local Flange and Web LimitStatesdChapter 2STRONG-AXIS MOMENT CONNECTIONSTO UNREINFORCED COLUMNSmH11006ooooooooThe actual m ment arm can be readily calculated as the distance be-t
38、ween the centers f the flanges r flange plates as illustrated in Figure2-1a. Alternatively, as stated in LRFD Specificati n C mmentary Sec-ti n K1.7, 0.95 times the beam depth has been c nservatively used f rin the past.ooooo o oooo ooo ooooo oooooo o oooooooooo o oooo ooooooo ooooo o o ooooo oooooo
39、oo o ooooo ooo ooo o ooooo oo ooooooooooooooo o oooo oooooo oooooo ooooooooooooo ooooooooo o oo ooo o oooo ooIn wind and l w-seismic applicati ns, it is ften p ssible c uple in the beam flanges r flange plates. The c rre-t use wide-flange c lumns with ut transverse stiffeners sp nding flange f rce i
40、s calculated as:and web d ubler plates at m ment-c nnected beams. Tuse an unreinf rced c lumn, the f ll wing criteria must(2.1-1)2be met:where1. The required strength (Secti n 2.1) must be less thanr equal t the design strength (Secti n 2.2); and,fact red beam flange f rce, tensile r c mpres-2. The
41、stiffness f the c lumn cr ss-secti n must be ad-sive, kipsequate t resist the bending def rmati ns in the c l-fact red beam end m ment, kip-in.umn flange (Secti n 2.3).m ment arm between the flange f rces, in.fact red beam axial f rce, kipsIf these criteria cann t be met, c lumn stiffening is re-qui
42、red.The f rmulati n f Equati n 2.1-1 is such that the c m-In high-seismic applicati ns, transverse stiffeners arebined effect f the m ment and axial f rce is transmittedn rmally required, as discussed in Secti n 2.3. H wever,thr ugh the flange c nnecti ns, ign ring any strength c n-it remains p ssib
43、le in many cases t use wide-flangetributi n fr m the web c nnecti n, which is usually m rec lumns in high-seismic applicati ns with ut web d ublerflexible.plates at m ment-c nnected beams.When the m ment t be devel ped is less than the fullflexural strength f the beam, as is c mm nly the casewhen a
44、drift criteri n g verns the design, and the axialf rce is relatively small, this calculati n is fairly straight-In an unreinf rced c lumn, c ncentrated f rces fr m thef rward. H wever, when the full flexural strength f thebeam flanges r flange plates are transferred l cally intbeam must be devel ped
45、, r when the axial f rce is large,the c lumn flanges. These c ncentrated f rces spreadsuch a m del seems t guarantee an verstress in the beamthr ugh the c lumn flange and flange-t -web fillet regi nflange, particularly f r a directly welded flange m mentint the web as illustrated in Figure 2-1a. She
46、ar is dis-c nnecti n. N netheless, the ab ve f rce transfer m delpersed between them in the c lumn web (panel-z ne) asremains acceptable because inelastic acti n int the rangeillustrated in Figure 2-1b. Ultimately, axial f rces in thef strain hardening all ws the devel pment f the designc lumn flang
47、es balance this shear as illustrated in Figureflexural strength f the beam in the c nnecti n (Huang et2-1c.al., 1973). Such self-limiting inelastic acti n is permittedin LRFD Specificati n Secti n B9. Alternatively, a webc nnecti n with a stiffness that is c mpatible with that fthe c nnecti ns f the
48、 beam flanges can be used t activateIn wind and l w-seismic applicati ns, beam end m ments,the full beam cr ss-secti n and reduce the p rti n carriedshears, and axial f rces are determined by analysis f rby the flanges.the l ads and l ad c mbinati ns in LRFD Specificati nN te that, if a c mp site m
49、ment c nnecti n is used be-Secti n A4.1. N te that the t tal design m ment is sel-tween the beam and c lumn, the calculati ns in Equati nsd m equal t the flexural strength f the beam(s). A ra-2.1-1and2.1-2mustbeadjustedbasedup ntheappr priateti nal appr ach such as that illustrated in Example 6-4 rsimilar t that pr p sed by Disque (1975) can be used inc njuncti n with these l ads and l ad c mbinati ns. Dif-ferent l ad c mbinati ns may be critical f r differentl cal-strength limit states.F r the general case, the beam end m ment is res lvedat the c lumn face int an effective tensi n-c m
