Study On Bearing Capacity Of Recyced Aggregate Concrete Filled Steel Tube Columns

The recycled aggregate concrete is poured into the steel tube to form a recycled aggregate concrete-filled-steel tube-column,which not only makes the structure have the advantages of composite structure,but also makes up for the shortage of the performance of the recycled concrete and saves energy and materials.The ferrule of the core recycled concrete was formed by the steel tube,therefore the recycled concrete has high compressive strength and deformability.Meanwhile,the compressed concrete enhances the stability of the steel tube.The concrete compressed steel tube structure can make the steel and recycled aggregate concrete two different kinds of materials to make best use of the advantages and bypass the disadvantages.Therefore,it will provide a broad prospect for the application of recycled concrete in practical Civil Engineering.The research on aggregate concrete-filled-steel tube-column is also an inevitable trend,in the wake of the developing technology of recycled concrete and concrete-filled-steel tube-column.In this paper,based on the Concrete Damage Model of ABAQUS,methods and parameters about 3D nonlinear simulation of recycled aggregate concrete-filled-circular steel tube-column(circular-CFST)for creating models were discussed,then the columns was simulated by the models.The reliability of models of the columns was verified,through comparing to experimental data of our research group and research in the literature.The variable factors effecting the bearing capacity of recycled aggregate concrete-filled-circular steel tube-column were investigated,including the aggregate replacement ratio,steel ratio,slenderness ratio and eccentricity.The result shows that:(1)The analysis of the model established in this paper is close to that of experiment of our research group and other finite element simulation which proves the reliability of finite element method in this paper,(2)The aggregate replacement ratio has no obvious influence on the failure process and configuration of columns,and does not significantly reduce its compressive bearing capacity,(3)The steel ratio increases obviously the bearing capacity of columns,and when the steel ratio is small,it behaves like brittle material,but the growth ratio of the bearing capacity slows down after reaching a certain extent,(4)When the slenderness increases,the bearing capacity and stiffness of columns decrease,(5)With the increase of eccentricity,the elastic stage becomes shorter,load-deformation curves becomes steeper,and the bearing capacity and stiffness of columns are greatly reduced.Combined with the summary of other calculation methods of bearing capacity and the calculation formula in the design cord about CFST,the new calculation formula of the axial and eccentric bearing capacity for recycled aggregate circular-CFST,under certain conditions,was established finally based on the result of finite element analysis.