Experimental Study On Seismic Behavior Of All Recycled Coarse Aggregate Concrete-filled Circular Steel Tube Columns

On the one hand,the rapid development of urban construction and construction industry can not be separated from concrete,As a component of concrete,Coarse aggregate accounts for 50% to 55% of the total concrete.Cement production reached24.14 million tons in china in 2013,Among them,the amount of sand is more than 80 million tons,so the demand for sand is very large.On the other hand,the waste concrete from discarded building?road and bridge reconstruction?concrete mixing station and earthquake natural disasters sharply increases.So it is of great significance for the sustainable development of building resources to make good use of waste concrete.But because that the mechanical properties of recycled concrete decline compared with ordinary concrete,now it is mostly used in road rather than structure system.Concrete filled steel tube structures not only improve the compressive strength and ductility of concrete,but also help the core concrete to enhance the stability of steel tube wall pressure.So it has been widely used in practical engineering.Recycled concrete filled steel tube not only retain the mechanical of steel tube,but also improve the compressive strength and ductility of recycled concrete,Recycled concrete filled steel tube providing a important way for the application of waste concrete in structural engineering.Research of the recycled concrete filled steel tube is in its infancy stage.Most of the research choose the replacement rate of recycled coarse aggregate as variable parameters to study the mechanical properties of concrete filled steel tube,and recycled coarse aggregate replace all ordinary coarse aggregate applied to concrete filled steel tubular structure in less research.In this paper,the central idea is experimental study on seismic behavior of high strength recycled aggregate concrete-filled circular steel tube columns,specific is as follows:(1)A low frequency cyclic loading test for seven recycled concrete-filled steel tube columns is studied,the damage process,hysteretic curve,skeleton curve,load carrying capacity,ductility,dissipation capacity and stiffness degeneration of columns are analyzed.Through experiments this paper analyzes the axial compression ratio,Steel ratio and Steel fiber on the seismic behavior of recycled concrete filled steel tube columns.(2)Constitutive relation of core iconcrete and steel tubes have been chosen from previous literature.This paper established finite element model of recycled concrete filled steel tube and simulated circular steel tube recycled concrete columns under low frequency cyclic loading.Finally compare the numerical simulation with experimental results.(3)In view of the accuracy and reliability of the simulation results,the influence of different concrete strength grades and slenderness ratio on the seismic performance of the specimens was analyzed by ABAQUS.