Concrete-filled steel tube columns under earthquake loads

Concrete-filled steel tubes (CFTs) have been used throughout the world in structures of varying heights and structural configurations, both in non-seismic and in high seismic zones. This review summarizes the behavior of circular and rectangular concrete-filled steel tube beam-columns and braces, particularly focused on their behavior when subjected to cyclic seismic loading. It begins with a discussion of the monotonic behavior of CFTs subjected to axial, flexural, and torsional loading, and summarizes the effects on CFT behavior of creep, shrinkage, composite action and residual stresses. The synopsis of monotonic behavior provides a basis for the subsequent discussion of research on the cyclic behavior of CFTs. The article concludes with a summary of publications in which current CFT design provisions are outlined for several non-seismic and seismic specifications throughout the world.