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AISC LRFD 1.pdf

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App. B5.] LOCAL BUCKLING 914kc=h/twherew, 035 . £ £ 0 . 763k ch = depth of web, in. (mm)t w = thickness of web, in. (mm)(b) For other sections:k c = 0.763(d) For stems of tees:when 0.75 E/ F < d / t < 1.03 E/ F :yyQ = 1.908 -1.22( d/ t) F / Esy(A-B5-9)whend/ t ³ 1.03 E/ F y:Errata9/4/01Q éF d t 2 ùs= 0.69 / ë y( / ) û(A-B5-10)whered = width of unstiffened compression element as defined in Section B5.1,in. (mm)t = thickness of unstiffened element, in. (mm)3b. Stiffened Compression ElementsWhen the width-thickness ratio of uniformly compressed stiffened elements(except perforated cover plates) exceeds the limit r stipulated in Section B5.1, areduced effective width b e shall be used in computing the design properties of thesection containing the element.(a) For flanges of square and rectangular sections of uniform thickness:b Ewhen ³ 1.40 :t fE é 0.38 Eùbe= 1.91tê1 - ú(A-B5-11)f êë( b / t ) f úûotherwise b e = b.(b) For other uniformly compressed elements:whenb E³ 1.49 :t fE é 0.34 Eùbe= 1.91tê1 - úf êë( b / t ) f úûotherwise b e = b.where<strong>LRFD</strong> Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION(A-B5-12)

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