Experimental Research And Finite Element Analysis Of Concrete Filled Steel Tubular Columns Under The Lateral Impact Load

Concrete-filled steel tube(CFST)has the advantages of high carrying capacity,good deformation performance,outstanding seismic performance,remarkable economic effect and convenient construction because of its ability to fully utilize the mechanical properties of steel and concrete.It has been widely used in high-rise structure and large span Structure.And these structures are likely to suffer from extreme loads during their service period,such as strong earthquakes,hurricanes,tsunamis,and the impact of vehicles.These loads are destructive,unpredictable,and rapid.It poses a serious threat to the safety of the structure.The impact of the vehicles is a kind of high-frequency and high-risk extreme action,and the damage caused by the impact is not even worse than that caused by the earthquake.At present,most of the research on the concrete-filled steel tubular structure focuses on the seismic performance of the concrete.The research on the impact resistance of concrete-filled steel tubular members is still in the initial stage,so it is necessary to study the impact resistance of concrete-filled steel tubular structures in depth.In this paper,the research on the impact resistance of CFST columns under horizontal lateral impact is carried out,and the horizontal impact test and finite element model simulation are completed.In this paper,the investigation and analysis of relevant literatures are carried out,including the literature review of engineering research,the research of relevant engineering specifications in domestic and foreign,the research on the strain rate effect of concrete and steel,the investigation of the impact resistance of steel pipe and concrete structural members,summary of the research on the impact of concrete structures.The investigation shows that there are some shortcomings in the research of impact resistance of concrete-filled steel tubular structures,and the problem of engineering collision is still to be solved further.In order to further explore the mechanical properties and failure mechanism of concrete-filled steel tubular columns under horizontal lateral impact and to reveal their failure mechanism,a series of horizontal lateral impact tests of concrete-filled steel tubular columns were carried out.The specimens included seven concrete-filled steel tubes Column and I part filled with concrete filled steel tubular column and 1 empty steel pipe column.The influence of key factors such as impact velocity,impact mass,impact energy,column constraint and concrete filling rate on the lateral impact dynamic response of concrete filled steel tubular column is considered.The results show that the impact resistance of concrete-filled steel tubular columns and partially filled concrete-filled steel tubular columns is significantly improved under the impact of lateral impact load,and the deformation is not significant,so the impact resistance is obviously improved.The fixed simply supported end columns were found to be prone to shear failure,whereas the cantilever columns suffered flexural damage.The impact force and residual displacement of the concrete filled steel tubular column are obviously increased with the increase of the impact velocity and the impact energy.In addition,based on the finite element analysis software ABAQUS,the finite element model of concrete filled steel tubular column under impact load is established.The accuracy of the finite element model is verified by comparison with the experimental data,from the aspects of impact force,deflection and failure mode The results show that the finite element model can simulate the dynamic performance of concrete-filled steel tube under impact.Then,the parameters of the model in the finite element model are analyzed,and the influence of the model parameters on the accuracy of the model is studied.Finally,the dynamic response of concrete-filled steel tubular columns under horizontal lateral impact is analyzed by the combination of test results and finite element model.The overall response of the whole process is described from the aspects of force-displacement curve and energy change.Combined with the numerical results,the failure mechanism of concrete-filled steel tubular columns is revealed.Based on the energy principle,the calculation method suitable for engineering application is put forward,and the relevant parameters are calculated by using the experimental data and the simulation data.