Development of Enhanced Seismic Compactness Requirements for Webs in Wide-Flange Steel Columns

Abstract

Recent full-scale testing of steel wide-flange columns under axial compression and cyclic lateral drifts for special moment frame applications showed that deep, slender columns could experience significant flexural strength degradation due to plastic hinge formation with buckling modes and considerable axial shortening within the hinge. Test results showed that the interaction between web and flange local buckling played a significant role for the observed degradation, even when the cross-sectional elements met the highly ductile limiting width-to-thickness ratios specified in the current seismic design standard for steel frames. These observations were also confirmed by numerical simulations. Enhanced limiting width-to-thickness ratios for the web of a wide-flange column for both special and intermediate steel moment frames are proposed to limit the severity of strength degradation and axial shortening.