Influence of Material Effects on Structural Ductility of Compact I-Shaped Beams

Abstract

This paper outlines the results from a research program aimed at studying the impact that certain features of the uniaxial material response representation of steel have on the structural behavior of compact I-shaped beams subjected to a moment gradient loading. The ductility of this structural behavior is quantified by the rotation capacity of the beam. It is shown in this work that uniaxial material response features, such as yield stress value, magnitude of strain hardening slope, and presence or absence of a yield plateau, all play fundamental roles in influencing the structural ductility of steel beam response. Two governing inelastic modal manifestations that occur in compact I-shaped beams at failure are also discussed. Although both modes display a significant degree of coupling between local and global components in the manifestations, one mode displays significantly higher capacity and structural ductility than the other. It is noted that geometric proportions of the beam alone are insufficient to predict which of the two modes govern at failure. It is concluded that, to properly account for flexural ductility in applications involving high performance steel, specifications must include provisions that ensure flexural ductility through the simultaneous consideration of geometric and material effects.