Cyclic Behavior of Structural Steels. I: Experiments

Abstract

This paper presents the nonproportional cyclic elastoplastic behavior of structural steels under biaxial loading, through a combined experimental and analytical study. In particular, the work seeks to illustrate the cyclic behavior within the yield plateau, which is an important feature of mild steel subjected to combined torsion-compression loading with proportional and nonproportional cyclic histories. A newly developed biaxial testing system used in the experiments is presented. Some important cyclic behavior of the steel within the yield plateau, such as the decrease and disappearance of the yield plateau, reduction of the elastic range, cyclic hardening, effect of nonproportional loading, and material memory are described and discussed. In a companion paper, Shen et al. carry out an analytical study by developing a new multiaxial two-surface plasticity model for structural steels. The experimental results are used to substantiate the analytical model.