Experimental research on seismic behavior of concrete filled CHS and SHS columns and steel beam planar frames

In order to realize the seismic behavior of concrete filled CHS (circular hollow section) and SHS (square hollow section) columns and steel beam planar frames, twelve test specimens were experimentally studied under constant axial load and cyclically lateral load. The column shape (CHS and SHS), steel ratio of the column section (CHS: " = 0.06, 0.103; SHS: " = 0.125, 0.126), axial load level of column(CHS: n = 0.06-0.60; SHS: n = 0.04-0.60), linear stiffness ratio of steel beam's to column's (CHS: i = 0.36-0.58; SHS: i = 0.34-0.62), are all considered as experimental parameters. The test results show that the lateral load (P) versus lateral displacement hysteretic curves of the frames are plump shuttle shape. The curves have no obvious strength and stiffness degradation. The axial load level of columns and steel ratio of the section have an evident effect on the strength and seismic behavior of the frames, and with the increase of axial load level of columns, the lateral ultimate strength of the frames becomes low, and the ductility of displacement and the capacity of energy dissipation also become descending, but the steel ratio has the opposite results. The frames with concrete filled CHS columns have a better seismic behavior than the frames with concrete filled SHS columns. All the test frames which are designed by the specification DBJ 13-51-2003 can meet the requirements of seismic design.