AISC LRFD 1.pdf

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App. K3.] DESIGN FOR CYCLIC LOADING (FATIGUE) 121Since the shear rigidity of the web system of steel joists and trusses is less than thatof a solid plate, their moment of inertia shall be taken as 85 percent of their chords.K3. DESIGN FOR CYCLIC LOADING (FATIGUE)This appendix applies to members and connections subject to high cycle loadingwithin the elastic range of stresses of frequency and magnitude sufficient to initiatecracking and progressive failure (fatigue).1. GeneralThe provisions of this section apply to stresses calculated on the basis of unfactoredloads. The maximum permitted stress due to unfactored loads is 0.66F y .Stress range is defined as the magnitude of the change in stress due to theapplication or removal of the unfactored live load. In the case of a stress reversal, thestress range shall be computed as the numerical sum of maximum repeated tensileand compressive stresses or the numerical sum of maximum shearing stresses ofopposite direction at the point of probable crack initiation.In the case of complete-joint-penetration butt welds, the maximum design stressrange calculated by Equation A-K3.1 applies only to welds with internal soundnessmeeting the acceptance requirements of Section 6.12.2 or 6.13.2 of AWS D1.1.No evaluation of fatigue resistance is required if the live load stress range is lessthan the threshold stress range, F TH . See Table A-K3.1.No evaluation of fatigue resistance is required if the number of cycles of applicationof live load is less than 2 10 4 .The cyclic load resistance determined by the provisions of this appendix is applicableto structures with suitable corrosion protection or subject only to mildly corrosiveatmospheres, such as normal atmospheric conditions.The cyclic load resistance determined by the provisions of this appendix is applicableonly to structures subject to temperatures not exceeding 300°F (150°C).The Engineer of Record shall provide either complete details including weld sizesor shall specify the planned cycle life and the maximum range of moments, shearsand reactions for the connections.2. Calculation of Maximum Stresses and Stress RangesCalculated stresses shall be based upon elastic analysis. Stresses shall not be amplifiedby stress concentration factors for geometrical discontinuities.For bolts and threaded rods subject to axial tension, the calculated stresses shallinclude the effects of prying action, if any.In the case of axial stress combined with bending, the maximum stresses, of eachkind, shall be those determined for concurrent arrangements of the applied load.For members having symmetric cross sections, the fasteners and welds shall bearranged symmetrically about the axis of the member, or the total stresses includingthose due to eccentricity shall be included in the calculation of the stress range.For axially loaded angle members where the center of gravity of the connectingwelds lies between the line of the center of gravity of the angle cross section and the<strong>LRFD</strong> Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION
122 DESIGN FOR CYCLIC LOADING (FATIGUE) [App. K3.center of the connected leg, the effects of eccentricity shall be ignored. If the centerof gravity of the connecting welds lies outside this zone, the total stresses, includingthose due to joint eccentricity, shall be included in the calculation of stress range.3. Design Stress RangeThe range of stress at service loads shall not exceed the stress range computed asfollows.(a) For stress categories A, B, B,C,D,EandE the design stress range, F SR , shallbe determined by Equation A-K3.1 or A-K3.1M.FSRC f= æ 0.333Fè ç ö÷ ³N øTH(A-K3.1)æçMetric:lFèSRæC= çèf´Nö. ö÷ ³ FTH÷(A-K3.1M)ø ø327 0 333whereF SR = Design stress range, ksi (MPa)C f = Constant from Table A-K3.1 for the categoryN = Number of stress range fluctuations in design life= Number of stress range fluctuations per day 365 years of designlifeF TH = Threshold fatigue stress range, maximum stress range for indefinitedesign life from Table A-K3.1, ksi (MPa)(b) For stress category F, the design stress range, F SR , shall be determined by EquationA-K3.2 or A-K3.2M.FSRC f= æ 0.167Fè ç ö÷ ³N øTH(A-K3.2)æçMetric:lFèSRæC= çèf´ 11´10 4 0.167ö÷ ³ FN øTHö÷ø(A-K3.2M)(c) For tension-loaded plate elements connected at their end by cruciform, T- orcorner details with complete-joint-penetration groove welds or partial-jointpenetrationgroove welds, fillet welds, or combinations of the preceding, transverseto the direction of stress, the design stress range on the cross section ofthe tension-loaded plate element at the toe of the weld shall be determined asfollows:Based upon crack initiation from the toe of the weld on the tension loaded plateelement the design stress range, F SR , shall be determined by Equation A-K3.1or A-K3.1M, for Category C which is equal toFSR =æ 44 ´ 10çè N8 0.333ö÷ ³ø10<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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Page 106 and 107: Sect. K1.] FLANGES AND WEBS WITH CO
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Page 112 and 113: 79Chap. LCHAPTER LSERVICEABILITY DE
Page 114 and 115: 81Chap. MCHAPTER MFABRICATION, EREC
Page 116 and 117: Sect. M4.] ERECTION 83(2) Bottom su
Page 118 and 119: Sect. M5.] QUALITY CONTROL 85The fa
Page 120 and 121: Sect. N3.] EVALUATION BY STRUCTURAL
Page 122 and 123: 89App. BAPPENDIX BDESIGN REQUIREMEN
Page 124 and 125: App. B5.] LOCAL BUCKLING 914kc=h/tw
Page 126 and 127: App. B5.] LOCAL BUCKLING 93é0.877
Page 128 and 129: App. E3.] DESIGN COMPRESSIVE STRENG
Page 130 and 131: App. F1.] DESIGN FOR FLEXURE 97For
Page 132 and 133: App. F1.] DESIGN FOR FLEXURE 99TABL
Page 134 and 135: App. F1.] DESIGN FOR FLEXURE 101Cri
Page 136 and 137: App. F3.] WEB-TAPERED MEMBERS 103j
Page 138 and 139: App. F3.] WEB-TAPERED MEMBERS 105Fw
Page 140 and 141: 107App. GAPPENDIX GPLATE GIRDERSThi
Page 142 and 143: App. G3.] DESIGN SHEAR STRENGTH 109
Page 144 and 145: App. G5.] FLEXURE-SHEAR INTERACTION
Page 146 and 147: App. H3.] ALTERNATIVE INTERACTION E
Page 148 and 149: 115App. JAPPENDIX JCONNECTIONS, JOI
Page 150 and 151: App. J3.] BOLTS AND THREADED PARTS
Page 152 and 153: App. K2.] PONDING 119æçMetric:lC
Page 156 and 157: App. K3.] DESIGN FOR CYCLIC LOADING
Page 174 and 175: NUMERICAL VALUES 141TABLE 2ItemShap
Page 176 and 177: NUMERICAL VALUES 143Klr123456789101
Page 178 and 179: NUMERICAL VALUES 145TABLE 3-50Desig
Page 180 and 181: NUMERICAL VALUES 147TABLE 4Values o
Page 182 and 183: NUMERICAL VALUES 149TABLE 5 (cont
Page 184 and 185: NUMERICAL VALUES 151TABLE 7Values o
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
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Page 200 and 201: Comm. A3.] MATERIAL 167and Chen, 19
Page 202 and 203: 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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Comm. I3.] FLEXURAL MEMBERS 217may
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Comm. I3.] FLEXURAL MEMBERS 219The
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Comm. I3.] FLEXURAL MEMBERS 221wher
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Comm. I3.] FLEXURAL MEMBERS 223proc
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Comm. I4.] COMBINED COMPRESSION AND
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Comm. I5.] SHEAR CONNECTORS 227tal
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229Comm. JCHAPTER JCONNECTIONS, JOI
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Comm. J1.] GENERAL PROVISIONS 231 P
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Comm. J2.] WELDS 2332b. Limitations
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Comm. J2.] WELDS 235When longitudin
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Comm. J2.] WELDS 237due to cyclic f
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Comm. J2.] WELDS 239(b) Plane 2-2,
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Comm. J3.] BOLTS AND THREADED PARTS
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Comm. J4.] DESIGN RUPTURE STRENGTH
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249Comm. KCHAPTER KCONCENTRATED FOR
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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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