AISC LRFD 1.pdf

Comm. K1.] FLANGES AND WEBS WITH CONCENTRATED FORCES 253load M u2G on the windward side of the connection, kip-in.(N-mm)d m1 , d m2= distance between flange forces in a moment connection,in. (mm)Conservatively, 0.95 times the beam depth has been used for d m in the past.If F u R v , no reinforcement is necessary, i.e., t req t w , where t w is the column webthickness.Consistent with elastic first order analysis, Equations K1-9 and K1-10 limitpanel-zone behavior to the elastic range. While such connection panels possesslarge reserve capacity beyond initial general shear yielding, the correspondinginelastic joint deformations may adversely affect the strength and stability of theframe or story (Fielding and Huang, 1971, and Fielding and Chen, 1973).Panel-zone shear yielding affects the overall frame stiffness and, therefore, the ultimate-strengthsecond-order effects may be significant. The shear/axial interactionexpression of Equation K1-10, as shown in Figure C-K1.4, is chosen to ensure elasticpanel behavior.If adequate connection ductility is provided and the frame analysis considers theinelastic panel-zone deformations, then the additional inelastic shear strength isrecognized in Equations K1-11 and K1-12 by the factor2æ 3bcft öcfç 1+ddt÷è b c wøThis inelastic shear strength has been most often utilized for design of frames inhigh seismic zones and should be used when the panel zone is to be designed tomatch the strength of the members from which it is formed.The shear/axial interaction expression incorporated in Equation K1-12 (see FigureC-K1.5) is similar to that contained in the previous editions of this SpecificationFig. C-K1.4. Interaction of shear and axial force—elastic.LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION