Behaviour Of Steel Beam To Concrete-Filled Steel Tubular Columns Frames

The paper describes the mechanical behaviours and practical calculation methods on concrete-filled CHS (circular hollow section) and SHS (square hollow section) steel tubular columns to steel beam structural frames. The main achievements can be summarized as follows:(1) Ten specimens of steel beam to concrete filled steel tubular column connections with outside stiffening rings were experimentally studied on the hysteretic behaviour under combined constant axial load and cyclic lateral load. The axial load level of concrete filled SHS column and width of joint stiffening ring were selected as the experimental parameters. The mechanical performance and failure mode of those connections were studied. The test results showed that the lateral load (P) versus lateral displacement(Δ) hysteretic curves for the connections were in plump shuttle shape. The curves had no obvious strength deterioration and stiffness degradation. It can be concluded that the tested connections had good seismic performance.(2) In order to realize the seismic behaviour of concrete filled CHS (Circular Hollow Section) and SHS (Square Hollow Section) columns to steel beam planar frames, twelve test specimens were experimentally studied under constant axial load and cyclically lateral load. Parameters, including the column section type (CHS and SHS), steel ratio of the column section (for CHS:α=0.06, 0.103; for SHS: α=0.125, 0.126), axial load level of column ( for CHS: n=0.06～0.6; for SHS: n=0.04～0.6), stiffness ratio of beam to column ( for CHS: i=0.36～0.58; for SHS: i=0.34～0.62), were varied in the test program. The mechanical performance and failure mode of those CFST frames were studied. The test results showed that the tested frames had good seismic performance and capacity of energy dissipation.(3) The mechanical performance of CFST frames under both monotonic and cyclic loads were analyzed by nonlinear elasto-plastic finite element method with material and geometrical nonlinear. The analytical results agreed well with experimental results. For calculating load versus displacement curves of CFST frames, the general purpose FEM software ABAQUS with concrete damage plastic model was used. The calculated results by ABAQUS agree well with experimental results. The mechanical mechanisms and failure modes of CFST frames were analyzed by ABAQUS.