Finite Element Analysis Of Mechanical Properties Of L-shaped Multi-cavity Concrete Filled Steel Tubular Special-shaped Columns

The special-shaped column(cross,T,L)is different from the traditional frame column.This kind of structural component can avoid the pillar protruding from the wall,and can obviously increase the living area of the house.Therefore,the special-shaped column structure system is undoubtedly a new residential structure system to meet people’s living needs and adapt to the contemporary architectural pattern,so it has a good market application prospect.L-shaped special-shaped column is the most widely used form of special-shaped column.This paper proposes a new type of special-shaped concrete-filled steel tubular special-shaped column,namely L-shaped multi-cavity concrete-filled steel tubular special-shaped column.In this paper,numerical simulation method is used to study the axial compression and seismic behavior of L-shaped multi-cavity concrete filled steel tubular special-shaped columns.Using ABAQUS finite element analysis software,three axially compressed models of L-shaped multi-cavity concrete filled steel tubular(CFST)special-shaped short columns are established,and the load-displacement curves and stress nephograms obtained by numerical simulation are compared with the experimental data in the literature.The error analysis of ultimate bearing capacity of specimens calculated by simulation is compared with the design bearing capacity of American,European and Chinese codes.The results show that the simulation method in this paper is correct.The effects of three parameters,concrete strength,steel strength and steel tube thickness,on the axial compressive behavior of L-shaped multi-cavity concrete filled steel tubular special-shaped short columns are analyzed.It can be concluded that the initial stiffness and ultimate bearing capacity of the specimens will increase with the increase of the strength of core concrete in L-shaped multi-cavity concrete filled steel tubular special-shaped short columns,but the ductility of the specimens will become worse;with the increase of the thickness of the steel tube,the stiffness and ultimate bearing capacity of the specimens will increase significantly,and the ductility of the specimens will also be improved to some extent;with the increase of the strength of steel,the specimens will The ultimate bearing capacity of the specimens increases obviously,but the initial stiffness of the specimens in the elastic stage hardly changes,and the increase of steel strength does not improve the deformation capacity of the specimens.Based on the modeling method of the axial compression model,the finite element simulation analysis of the seismic behavior of L-shaped multi-cavity concrete filled steel tubular special-shaped columns is carried out,and the mechanism and failure mode of the member under low cyclic repeated load are systematically studied.Fourteen models of L-shaped multi-cavity concrete filled steel tubular special-shaped columns with different parameters were established,including concrete strength,steel strength,steel tube thickness,aspect ratio and axial compression ratio.The results show that the smaller the ratio of height to width,the stronger the load-bearing capacity of special-shaped columns,the higher the energy dissipation performance,but the worse the ductility at the same time;with the increase of the thickness of steel tubes,the load-bearing capacity,stiffness and energy dissipation capacity of special-shaped columns will increase,while the deformation capacity of special-shaped columns will increase slightly with the increase of the thickness of steel tubes,but the influence is not significant.At the same time,the steel content of special-shaped columns will increase and the economic cost will increase.When the concrete strength increases,the bearing capacity of special-shaped columns increases slightly,but the ductility of members decreases,and the seismic performance also decreases;the axial compression ratio has little effect on the ultimate bearing capacity of L-shaped multi-cavity concrete filled steel tubular special-shaped columns,which mainly affects the ductility of special-shaped columns.When the axial compression ratio is too large,the ductility of special-shaped columns obviously decreases,so attention should be paid to rationality in practical application.Controlling the axial compression ratio of special-shaped columns;with the increase of steel strength,the ultimate bearing capacity of special-shaped columns increases obviously,steel strength has little effect on improving ductility of specimens,but steel strength can significantly improve the energy dissipation performance of specimens.