Elasto-plastic instability of steel compression tubular members subjected to cyclically applied Bi-directional horizontal loads

摘要

The unprecedented damage to steel structures during the 1995 Hyogoken-Nanbu Earthquake not only prompted the revision of the Japanese seismic code but also emphasized the need for a comprehensive understanding of buckling damage as well as seismic response, which in reality is complex and multidirectional, as opposed to the conventionally assumed uni-directional approach. Thus, this study investigated the effects of bi-directional load histories on the coupled instability of each plate elements of tubular columns widely used in the construction of elevated highways and building structures. Test results indicate that, in comparison with uniaxial displacement paths, biaxial displacement patterns lead to significant degradation of stiffness, strength and ductility of tubular columns, namely the buckling wave can transmit rapidly in the circumferential direction under the biaxial loading, particularly the non-proportional loading.