Axial Behavior Of Square Double Skin Steel Stub Columns Filled With Demolished Concrete Lump

Concrete filled double-skin steel tubular(CFDST) is a new type of concrete-filled steel tube,it has the advantages of ordinary concrete filled steel tubular column (CFT) and new features such as light weight and bending stiffness. From the national strategic background of resource-conserving environment and friendly society, based on preliminary study of waste concrete components on the steel tube recycled block mixed component that carried by south China university of technology and our university, combining with the question of waste concrete component reuse and the new form of CFDST, this paper use the method of combining the experiment and theory, study the axial compression performance of CFDST. The following concrete several aspects were carried out.(1)Review the background of the domestic and foreign researches about steel pipe renewable block mixed component and CFDST. The section demonstrates the rationality of CFDST that filled with recycled concrete block.(2)Twelve stub columns were tested that the main experimental parameters were the diameter-to-thickness ratio, mixing ratio and hollow section ration. All specimens have a good performance of ductility and late bearing capacity. When the width-thickness is72, specimens surface occur continuous damage while the damage is local when width-thickness is120, When the width-thickness is72and have a same mixing ratio, CFDST have the same bearing capacity with CFT. When the mixing ratio is0and width-thickness is120, the bearing capacity of CFDST increase16%than CFT. When the new concrete have similar compressive strength with old and mixing ratio is25%, the bearing capacity of CFDST increase18.8%than CFT.(3) Based on the calculation formula in existing specifications, considering the influence of large width-thickness, the effective width method is adopted that formula are derived to predict the bearing capacity, the proposed formula was found in good agreement with experiment results.(4) Using finite element software ANSYS10.0, based on nonlinear analysis with both geometrical and material nonlinearity, the process of axial compression test on short column were simulated by reasonable way of mesh modeling and load. The ultimate bearing capacity were concluded. Simulation results were in good agreement with those obtained with the test result proves the feasibility of finite element analysis method.