AISC LRFD 1.pdf

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Comm. C3.] STABILITY BRACING 201Parallel chord trusses with both chords extended to the end of the span and attachedto supports can be treated like beams. In Equations C3-7 through C3-11, M u may betaken as the maximum compressive chord force times the depth of the truss to determinethe brace strength and stiffness requirements. Cross-section distortion effects, sec, need not be considered when full-depth cross frames are used for bracing.When either chord does not extend to the end of the span, consideration should begiven to control twist near the ends of the span by the use of cross frames or ties.LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION
202Comm. DCHAPTER DTENSION MEMBERSD1. DESIGN TENSILE STRENGTHDue to strain hardening, a ductile steel bar loaded in axial tension can resist, withoutfracture, a force greater than the product of its gross area and its coupon yield stress.However, excessive elongation of a tension member due to uncontrolled yielding ofits gross area not only marks the limit of its usefulness, but can precipitate failure ofthe structural system of which it is a part. On the other hand, depending upon thereduction of area and other mechanical properties of the steel, the member can failby fracture of the net area at a load smaller than required to yield the gross area.Hence, general yielding of the gross area and fracture of the net area both constitutefailure limit states. The relative values of t given for yielding and fracture reflectthe same basic difference in factor of safety as between design of members anddesign of connections in the AISC ASD Specification.The length of the member in the net area is negligible relative to the total length ofthe member. As a result, the strain hardening condition is quickly reached andyielding of the net area at fastener holes does not constitute a limit state of practicalsignificance.D2. BUILT-UP MEMBERSThe slenderness ratio L/rof tension members other than rods, HSS, or strapsshould preferably not exceed the limiting value of 300. This slenderness limit recommendedfor tension members is not essential to the structural integrity of suchmembers; it merely assures a degree of stiffness such that undesirable lateral movement(“slapping” or vibration) will be unlikely.See Section B7 and Commentary Section E4.D3. PIN-CONNECTED MEMBERS AND EYEBARSForged eyebars have generally been replaced by pin-connected plates or eyebarsthermally cut from plates. Provisions for the proportioning of eyebars contained inthe LRFD Specification are based upon standards evolved from long experiencewith forged eyebars. Through extensive destructive testing, eyebars have beenfound to provide balanced designs when they are thermally cut instead of forged.The somewhat more conservative rules for pin-connected members of nonuniformcross section and those not having enlarged “circular” heads are likewise based onthe results of experimental research (Johnston, 1939).Somewhat stockier proportions are provided for eyebars and pin-connected membersfabricated from steel having a yield stress greater than 70 ksi (485 MPa), inorder to eliminate any possibility of their “dishing” under the higher design stress.LRFD 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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Page 186 and 187: NUMERICAL VALUES 153f vVAwnTABLE 8-
Page 190 and 191: NUMERICAL VALUES 157hf vVAwnTABLE 9
Page 194 and 195: NUMERICAL VALUES 161ht wf vVAwnTABL
Page 196 and 197: 163COMMENTARYon the Load and Resist
Page 198 and 199: Comm. A2.] TYPES OF CONSTRUCTION 16
Page 200 and 201: Comm. A3.] MATERIAL 167and Chen, 19
Page 202 and 203: Comm. A3.] MATERIAL 169than the ant
Page 204 and 205: Comm. A4.] LOADS AND LOAD COMBINATI
Page 206 and 207: Comm. A5.] DESIGN BASIS 173where =
Page 208 and 209: Comm. A5.] DESIGN BASIS 175( )bsln(
Page 210 and 211: 177Comm. BCHAPTER BDESIGN REQUIREME
Page 212 and 213: Comm. B5.] LOCAL BUCKLING 179(c) Al
Page 214 and 215: Comm. B5.] LOCAL BUCKLING 181load.
Page 216 and 217: Comm. B7.] LIMITING SLENDERNESS RAT
Page 218 and 219: Comm. C1.] SECOND ORDER EFFECTS 185
Page 220 and 221: Comm. C1.] SECOND ORDER EFFECTS 187
Page 222 and 223: Comm. C2.] FRAME STABILITY 189Buckl
Page 224 and 225: Comm. C2.] FRAME STABILITY 191Notes
Page 226 and 227: Comm. C2.] FRAME STABILITY 193Where
Page 228 and 229: Comm. C3.] STABILITY BRACING 195age
Page 230 and 231: Comm. C3.] STABILITY BRACING 197pla
Page 232 and 233: Comm. C3.] STABILITY BRACING 199The
Page 236 and 237: 203Comm. ECHAPTER ECOLUMNS AND OTHE
Page 238 and 239: Comm. E4.] BUILT-UP MEMBERS 205TABL
Page 240 and 241: Comm. F1.] DESIGN FOR FLEXURE 207ha
Page 242 and 243: Comm. F1.] DESIGN FOR FLEXURE 2092b
Page 244 and 245: Comm. F4.] BEAMS AND GIRDERS WITH W
Page 246 and 247: Comm. H2.] UNSYMMETRIC MEMBERS AND
Page 248 and 249: Comm. I2.] COMPRESSION MEMBERS 215d
Page 250 and 251: Comm. I3.] FLEXURAL MEMBERS 217may
Page 252 and 253: Comm. I3.] FLEXURAL MEMBERS 219The
Page 254 and 255: Comm. I3.] FLEXURAL MEMBERS 221wher
Page 256 and 257: Comm. I3.] FLEXURAL MEMBERS 223proc
Page 258 and 259: Comm. I4.] COMBINED COMPRESSION AND
Page 260 and 261: Comm. I5.] SHEAR CONNECTORS 227tal
Page 262 and 263: 229Comm. JCHAPTER JCONNECTIONS, JOI
Page 264 and 265: Comm. J1.] GENERAL PROVISIONS 231 P
Page 266 and 267: Comm. J2.] WELDS 2332b. Limitations
Page 268 and 269: Comm. J2.] WELDS 235When longitudin
Page 270 and 271: Comm. J2.] WELDS 237due to cyclic f
Page 272 and 273: Comm. J2.] WELDS 239(b) Plane 2-2,
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Comm. K1.] FLANGES AND WEBS WITH CO
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Comm. K1.] FLANGES AND WEBS WITH CO
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Comm. K2.] PONDING 255Even on the b
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257Comm. LCHAPTER LSERVICEABILITY D
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Comm. L5.] CORROSION 259orthotropic
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Comm. M4.] ERECTION 261It is sugges
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Comm. N4.] EVALUATION BY LOAD TESTS
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Comm. N5.] EVALUATION REPORT 265N5.
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267Comm. A-EAPPENDIX ECOLUMNS AND O
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Comm. App. F3.] WEB-TAPERED MEMBERS
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271Comm. A-GAPPENDIX GPLATE GIRDERS
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273Comm. A-KAPPENDIX JCONNECTIONS,
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Comm. J2.] WELDS 275found to be con
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Comm. K3.] DESIGN FOR CYCLIC LOADIN
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279ReferencesAckroyd, M. H., and Ge
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REFERENCES 281Bjorhovde, R. (1972),
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REFERENCES 283Fielding, D. J., and
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REFERENCES 285Johnson, D. L. (1985)
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REFERENCES 287Ollgaard, J. G., Slut
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REFERENCES 289Zhou, S. P., and Chen
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SUPPLEMENTARY BIBLIOGRAPHY 291Kotec
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Metric Conversion Factors for Commo
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