AISC LRFD 1.pdf

102 DESIGN FOR FLEXURE [App. F1.hr yct ft w= clear distance between flanges less the fillet or corner radius at each flange,in. (mm)= radius of gyration of compression flange about y axis or if reverse curvaturebending, smaller flange, in. (mm)= flange thickness, in. (mm)= web thickness, in. (mm)F2. DESIGN FOR SHEAR2. Design Shear StrengthThe design shear strength of stiffened or unstiffened webs is V n ,where v = 0.90V n = nominal shear strength defined as follows:(a) For h/ t £ 1.10 k E/ F :w v ywV= 0.6F An yw w(A-F2-1)(b) For 1.10 kE/ F < h/ t £ 1.37 kE/ F :v yw w v ywVn = 0.6 FywAw(1.10 kvE/ Fyw) /( h/ tw)(A-F2-2)(c) Forh/ t > 1.37 k E/ F :w v ywV = A (0.91 Ek ) /( h/ t )n w v w2(A-F2-3)where2k v = 5+ 5/( a/ h)= 5 when a / h > 3 or a / h > [260/ (h / t)] 2a = distance between transverse stiffeners, in. (mm)h = for rolled shapes, the clear distance between flanges less the fillet or cornerradius, in. (mm)= for built-up welded sections, the clear distance between flanges, in. (mm)= for built-up bolted or riveted sections, the distance between fastener lines, in.(mm)3. Transverse StiffenersTransverse stiffeners are not required in plate girders where h / t w £ 245 . E/F ywor where the required shear, V u , as determined by structural analysis for the factoredloads, is less than or equal to 0.6 v A w F yw C v , where v = 0.90 and the shear coefficientC v defined in Appendix G3 is determined for k v = 5.Transverse stiffeners used to develop the web design shear strength as provided inAppendix F2.2 shall have a moment of inertia about an axis in the web center forstiffener pairs, or about the face in contact with the web plate for single stiffeners,which shall not be less than at 3 w j, whereLRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION