Structural behavior and characteristics of concrete-filled tubular frames

In order to clarify the elasto-plastic behavior of the frame consisting of concrete-filled steel tubular (CFT) columns and H-shaped steel beams under seismic loading, portal frame specimens were tested under constant vertical loads on columns and alternately repeated horizontal load. Experimental parameters were: axial load ratio, and width-to-thickness ratio, and yield mode. D sub s factors were calculated from the load-deflection curves of all specimens. It was observed that all specimens showed fairly stable hysteresis loops, and the earthquake resistant capacity of the CFT frame was better than the similar steel frame.