Seismic behavior of concrete-encased steel cross-shaped columns

Abstract

Experiments were performed to investigate the seismic behavior of concrete-encased steel cross-shaped (CESC) columns. Four specimens subjected to combined constant axial load and cyclic lateral load were tested to study the effects of the axial compression ratio, the steel ratio, and the loading angle on the behavior (strength, stiffness, ductility, and energy dissipation capacity) of CESC columns. Experimental results suggest that the maximum lateral load increases with an increase in the axial compression ratio, while the displacement ductility decreases, and the stiffness degrades seriously. The maximum lateral load and the displacement ductility increase significantly with an increase in the steel ratio, whereas the stiffness degrades slightly. The maximum lateral load at the loading angle 45° is larger than that at the loading angle 0°, but the displacement ductility at the loading angle 45° is lower than that at the loading angle 0°. CESC columns exhibit good ductility, deformation capacity and energy dissipation capacity. Furthermore, a finite element analysis was also carried out to simulate the behavior of the specimens. The results obtained from the finite element analysis agree well with the experimental results. Compared with reinforced concrete cross-shaped columns, CESC columns show higher lateral bearing capacity and better seismic performance.