PRE-COMPRESSED CONCRETE-FILLED STEEL TUBE FOR HIGH EARTHQUAKE RESISTING PERFORMANCE OF STEEL COLUMNS

Abstract

Strength of the circular-shaped concrete-filled steel tubes (CFT) is enhanced significantly due to the confinement provided by the surrounding steel plates. The effectiveness of the confinement depends on several factors such as column slenderness，diameter to thickness ratio，strengths of steel and concrete，the loading method and boundary conditions，and the interface condition between steel and intemal concrete. A new technique is introduced in this study to increase the effectiveness of the confinement in order to improve the strength and the ductility of CFT columns. The CFT column used in this study is different from the conventional CFT column in that the concrete is compressed prior to hardening using two circular steel plates placed at both ends of the column.