Experimental research on seismic behavior of T-shaped concrete-filled steel tube columns

Special-shaped column structures can improve residential architectural space,compared with traditional frame structures.However,there are strict limitations for widely used special-shaped reinforced concrete(RC) columns in seismic behaviors,which hampers further application of special-shaped columns.Due to the increase of steel ratio and constraint effect to concrete,special-shaped concrete-filled steel tube(CFST) columns are superior on the seismic behavior to RC columns.However,the advantages are more or less weakened by steel plates' premature local buckling and the separation between steel tube and concrete at inward corners.Innovative inner reinforcement stiffeners are firstly put forward in this paper.Experimental investigation on hysteretic properties of three T-shaped columns was conducted,including one non-stiffened CFST columns,one stiffened CFST column and one RC column.Failure modes and hysteretic properties of the specimens were investigated,and the mechanism of reinforcement stiffeners and confinement provided by T-shaped tube were in-depth researched.The experimental results reveal that:compared with RC columns,the CFST columns has less damage,larger initial stiffness,higher resistance and better energy dissipation capacity;the reinforcement stiffeners can effectively restrain the out-of-plain deformation near the center plates and the inward corners,to enhance the teamwork of steel tube and concrete;the specimen with reinforcement stiffeners presents better initial stiffness,resistance and ductility.