Experimental study on hysteretic behavior of brick aggregate geopolymer recycled concrete-filled circular steel tubular column
In order to explore the feasibility of reuse of waste clay bricks,a series of experimental studies were conducted on hysteretic behavior of 6 brick aggregate geopolymer recycled concrete-filled circular steel tubular(BAGRC-FST)columns.Key parameters including steel tube thickness(4 mm and 6 mm),replacement ratio of brick aggregate(0%,50%,100%)and axial compression ratio(0.05,0.25 and 0.50)were considered.The failure mode,skeleton curves and hysteretic curves of the specimens under reciprocating load were obtained,and the change law of seismic performance indicators such as stiffness degradation,hysteresis behavior,peak bearing capacity,ductility,bearing capacity degradation and energy-dissipation capacity of the components were analyzed.The results indicated that the failure mode of the specimen is characterized by bulging and cracking at the bottom of specimens and the breakage of the core concrete in the area where plastic hinges appear,which is similar to that of ordinary CFST columns.The increase of brick aggregate replacement ratio of brick aggregate and axial compression ratio reduces the bearing capacity of specimens,and the increase of steel tube thickness will increase the bearing capacity of specimens.The hysteretic curves of specimens were plump without obvious pinching effect,implying that the BAGRC-FST columns had desired energy-dissipation capacity.Moreover,increasing the axial compression ratio reduces the deformation capacity of specimens and accelerates the degradation of stiffness and bearing capacity.However,increasing the thickness of the steel tube can improve the deformation ability of specimens.The substitution rate of brick aggregate has limited influence on stiffness degradation,ductility,bearing capacity and energy dissipation capacity of the BAGRC-FST columns.