Behavior of Eccentrically Loaded Concrete-Filled Steel Tubular Columns

Abstract

Beam columns of concrete-filled steel tubular (CFT) columns are designed using a design formula established by the Architectural Institute of Japan (AIJ). However, the scope of the formula in the current AIJ standard is limited to ordinary material strengths, and a rational mathematical model which makes it possible to reproduce load-deformation behavior in CFT columns has not yet been established. The main objectives of this research were to investigate the effect of higher material strengths on the flexural behavior and to create mathematical models of the steel tube and filled concrete. Adequate study of the effects of the section shape, diameter (width)-to-thickness ratio, and the combination of strengths of the steel tube and filled concrete was included in the scope of this investigation. Based on the experimental results of 65 eccentric compression tests, an analytical model for the restoring force characteristics of the flexural behavior of CFT columns is proposed, and is found to reproduce experimental results such as the synergistic interaction between the steel tube and filled concrete with good accuracy.