| Concrete filled steel tube(CFST)has been widely used in practical projects because of its advantages of high bearing capacity,outstanding seismic performance,light weight,convenient construction and economic cost.A large number of engineering practices show that in actual operation,steel tube concrete has interface defects under the action of load coupling factors such as stress and heat.The appearance of defects will reduce the ultimate bearing capacity of concrete-filled steel tubes and affect the working mechanism and mechanical properties of concrete-filled steel tubes.in view of this,based on this,this paper analyzes and studies the ultimate bearing capacity,working mechanism and mechanical properties of concrete-filled steel tubes after interface defects and the influence of parameters.In order to study the performance of steel tube concrete interface defects,the following work is carried out in this paper:(1)The ultimate bearing capacity of CFST interface defects is deduced by the limit equilibrium method.Based on the limit equilibrium method,the ultimate bearing capacity of CFST interface defects is theoretically deduced.The approximate formulas for calculating the ultimate bearing capacity of axially compressed short columns with three common interface defects of concrete filled steel tubes are established.Combining with the existing research literatures,the results show that the reduction trend of the bearing capacity deduced in this paper is consistent with that of the literature test values,which is quite consistent,and verifies the feasibility and accuracy of theoretical deduction in this chapter(2)In this paper,the mechanical properties of the concrete filled steel tube are studied by ABAQUS with large finite element analysis software.Firstly,the software analysis process is introduced,and the finite element model is established to verify the feasibility of the model.And then analyzes the steel tube concrete pavement and debonding defect effect on the mechanical properties,the relationship between axial load and strain,failure mode,the contact stress between steel tube and concrete and defects of the biggest limit are analyzed.(3)The finite element parameter analysis of steel tube concrete interface defect was carried out by ABAQUS finite element analysis software.The influence of the degumming defect on the ductility and ultimate bearing capacity,the influence on the ultimate bearing capacity and the influence of the degumming thickness on the ultimate bearing capacity are analyzed.The influence of steel strength,concrete strength and steel tube thickness on bearing capacity is analyzed,and the influence of constraint coefficient on bearing capacity is discussed. |
