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267Comm. A-EAPPENDIX ECOLUMNS AND OTHER COMPRESSION MEMBERSE3. DESIGN COMPRESSIVE STRENGTH FORFLEXURAL-TORSIONAL BUCKLINGThe equations in Appendix E3 for determining the flexural-torsional elastic bucklingloads of columns are derived in texts on structural stability (Timoshenko andGere, 1961; Bleich, 1952; Galambos, 1968; and Chen and Atsuta, 1977, for example).Since these equations for flexural-torsional buckling apply only to elasticbuckling, they must be modified for inelastic buckling when F cr > 0.5F y . This isaccomplished through the use of the equivalent slenderness factor λ e = F y / F e .<strong>LRFD</strong> Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION
268Comm. A-FAPPENDIX FBEAMS AND OTHER FLEXURAL MEMBERSF1. DESIGN FOR FLEXUREThree limit states must be investigated to determine the moment capacity of flexuralmembers: lateral-torsional buckling (LTB), local buckling of the compressionflange (FLB), and local buckling of the web (WLB). These limit states depend,respectively, on the beam slenderness ratio L b /r y , the width-thickness ratio b/tofthe compression flange and the width-thickness ratio h/t w of the web. For convenience,all three measures of slenderness are denoted by .Variations in M n with L b are shown in Figure C-F1.1. The discussion of plastic,inelastic, and elastic buckling in Commentary Section F1 with reference to lateral-torsionalbuckling applies here except for an important difference in the significanceof p for lateral-torsional buckling and local buckling. Values of p for FLBand WLB produce a compact section with a rotation capacity of about three (afterreaching M p ) before the onset of local buckling, and therefore meet the requirementsfor plastic analysis of load effects (Commentary Section B5). On the otherhand, values of p for LTB do not allow plastic analysis because they do not providerotation capacity beyond that needed to develop M p . Instead L b L pd (Section F1.3)must be satisfied.Analyses to include restraint effects of adjoining elements are discussed inGalambos (1998). Analysis of the lateral stability of members with shapes not coveredin this appendix must be performed according to the available literature(Galambos, 1998).See the Commentary for Section B5 for the discussion of the equation regarding thebending capacity of circular sections.F3. WEB-TAPERED MEMBERS1. General RequirementsThe provision contained in Appendix F3 covers only those aspects of the design oftapered members that are unique to tapered members. For other criteria of designnot specifically covered in Appendix F3, see the appropriate portions of this Specificationand Commentary.The design of wide-flange columns with a single web taper and constant flangesfollows the same procedure as for uniform columns according to Section E2, exceptthe column slenderness parameter c for major axis buckling is determined for aslenderness ratio K L/r ox , and for minor axis buckling for KL/r oy , where K is aneffective length factor for tapered members, K is the effective length factor for pris-<strong>LRFD</strong> Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION
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LOAD AND RESISTANCEFACTOR DESIGNSPE
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iiCopyright © 2000byAmerican Insti
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vTABLE OF CONTENTSSYMBOLS . . . . .
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TABLE OF CONTENTSviiSPECIFICATION (
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TABLE OF CONTENTSixSPECIFICATION (C
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TABLE OF CONTENTSxiCOMMENTARY (Cont
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SYMBOLSxviistrength (for those stee
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SYMBOLSxixS eff Effective section m
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SYMBOLSxxit s Web stiffener thickne
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xxiiiGLOSSARYAlignment chart for co
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GLOSSARYxxvEffective moment of iner
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GLOSSARYxxviiLateral bracing member
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GLOSSARYxxixPost-buckling strength.
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GLOSSARYxxxiStrain-hardening strain
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1CHAPTER AGENERAL PROVISIONSA1. SCO
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Sect. A3.] MATERIAL 3Cold-Formed We
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Sect. A3.] MATERIAL 5ASTM A449 bolt
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Sect. A6.] REFERENCED CODES AND STA
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Sect. A7.] DESIGN DOCUMENTS 9tion A
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Sect. B4.] STABILITY 11(a) When the
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Sect. B10.] PROPORTIONS OF BEAMS AN
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Sect. B10.] PROPORTIONS OF BEAMS AN
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17Chap. CCHAPTER CFRAMES AND OTHER
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Sect. C3.] STABILITY BRACING 19all
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Sect. C3.] STABILITY BRACING 214. B
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Sect. C3.] STABILITY BRACING 231.0;
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Sect. D3.] PIN-CONNECTED MEMBERS AN
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27Chap. ECHAPTER ECOLUMNS AND OTHER
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Sect. E4.] BUILT-UP MEMBERS 29(a) F
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31Chap. FCHAPTER FBEAMS AND OTHER F
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Sect. F1.] DESIGN FOR FLEXURE 33Lp=
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Sect. F2.] DESIGN FOR SHEAR 35Lpd
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37Chap. GCHAPTER GPLATE GIRDERSI-sh
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Sect. H3.] ALTERNATIVE INTERACTION
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Sect. I2.] COMPRESSION MEMBERS 41ti
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Sect. I3.] FLEXURAL MEMBERS 434. Lo
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Sect. I3.] FLEXURAL MEMBERS 45welde
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Sect. I5.] SHEAR CONNECTORS 47A c =
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49Chap. JCHAPTER JCONNECTIONS, JOIN
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Sect. J1.] GENERAL PROVISIONS 518.
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Sect. J2.] WELDS 53Welding ProcessT
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Sect. J2.] WELDS 55For end-loaded f
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Sect. J2.] WELDS 57Types of Weld an
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Sect. J3.] BOLTS AND THREADED PARTS
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Sect. J4.] DESIGN RUPTURE STRENGTH
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Sect. J8.] BEARING STRENGTH 69J6. F
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71Chap. KCHAPTER KCONCENTRATED FORC
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Sect. K1.] FLANGES AND WEBS WITH CO
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For P u 0.4P yR v = 0.60F y d c t
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Sect. K3.] DESIGN FOR CYCLIC LOADIN
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79Chap. LCHAPTER LSERVICEABILITY DE
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81Chap. MCHAPTER MFABRICATION, EREC
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Sect. M4.] ERECTION 83(2) Bottom su
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Sect. M5.] QUALITY CONTROL 85The fa
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Sect. N3.] EVALUATION BY STRUCTURAL
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89App. BAPPENDIX BDESIGN REQUIREMEN
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App. B5.] LOCAL BUCKLING 914kc=h/tw
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App. B5.] LOCAL BUCKLING 93é0.877
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App. E3.] DESIGN COMPRESSIVE STRENG
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App. F1.] DESIGN FOR FLEXURE 97For
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App. F1.] DESIGN FOR FLEXURE 99TABL
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App. F1.] DESIGN FOR FLEXURE 101Cri
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App. F3.] WEB-TAPERED MEMBERS 103j
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App. F3.] WEB-TAPERED MEMBERS 105Fw
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107App. GAPPENDIX GPLATE GIRDERSThi
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App. G3.] DESIGN SHEAR STRENGTH 109
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App. G5.] FLEXURE-SHEAR INTERACTION
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App. H3.] ALTERNATIVE INTERACTION E
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115App. JAPPENDIX JCONNECTIONS, JOI
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App. J3.] BOLTS AND THREADED PARTS
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App. K2.] PONDING 119æçMetric:lC
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App. K3.] DESIGN FOR CYCLIC LOADING
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NUMERICAL VALUES 141TABLE 2ItemShap
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NUMERICAL VALUES 143Klr123456789101
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NUMERICAL VALUES 145TABLE 3-50Desig
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NUMERICAL VALUES 147TABLE 4Values o
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NUMERICAL VALUES 149TABLE 5 (cont
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NUMERICAL VALUES 151TABLE 7Values o
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NUMERICAL VALUES 153f vVAwnTABLE 8-
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NUMERICAL VALUES 157hf vVAwnTABLE 9
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NUMERICAL VALUES 161ht wf vVAwnTABL
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163COMMENTARYon the Load and Resist
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Comm. A2.] TYPES OF CONSTRUCTION 16
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Comm. A3.] MATERIAL 167and Chen, 19
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Comm. A3.] MATERIAL 169than the ant
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Comm. A4.] LOADS AND LOAD COMBINATI
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Comm. A5.] DESIGN BASIS 173where =
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Comm. A5.] DESIGN BASIS 175( )bsln(
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177Comm. BCHAPTER BDESIGN REQUIREME
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Comm. B5.] LOCAL BUCKLING 179(c) Al
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Comm. B5.] LOCAL BUCKLING 181load.
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Comm. B7.] LIMITING SLENDERNESS RAT
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Comm. C1.] SECOND ORDER EFFECTS 185
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Comm. C1.] SECOND ORDER EFFECTS 187
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Comm. C2.] FRAME STABILITY 189Buckl
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Comm. C2.] FRAME STABILITY 191Notes
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Comm. C2.] FRAME STABILITY 193Where
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Comm. C3.] STABILITY BRACING 195age
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Comm. C3.] STABILITY BRACING 197pla
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Comm. C3.] STABILITY BRACING 199The
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Comm. C3.] STABILITY BRACING 201Par
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203Comm. ECHAPTER ECOLUMNS AND OTHE
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Comm. E4.] BUILT-UP MEMBERS 205TABL
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Comm. F1.] DESIGN FOR FLEXURE 207ha
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Comm. F1.] DESIGN FOR FLEXURE 2092b
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Comm. F4.] BEAMS AND GIRDERS WITH W
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Comm. H2.] UNSYMMETRIC MEMBERS AND
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Comm. I2.] COMPRESSION MEMBERS 215d
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Page 292 and 293: Comm. L5.] CORROSION 259orthotropic
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Page 308 and 309: Comm. J2.] WELDS 275found to be con
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Page 312 and 313: 279ReferencesAckroyd, M. H., and Ge
Page 314 and 315: REFERENCES 281Bjorhovde, R. (1972),
Page 316 and 317: REFERENCES 283Fielding, D. J., and
Page 318 and 319: REFERENCES 285Johnson, D. L. (1985)
Page 320 and 321: REFERENCES 287Ollgaard, J. G., Slut
Page 322 and 323: REFERENCES 289Zhou, S. P., and Chen
Page 324 and 325: SUPPLEMENTARY BIBLIOGRAPHY 291Kotec
Page 326 and 327: Metric Conversion Factors for Commo
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