Pendulum Impact Test And Numerical Simulation Of Square Steel Tube Reinforced RC Column

In recent years,the total mileage of highways in my country,the number of trucks and the tonnage of trucks have been increasing year by year,which virtually increases the risk of piers of highway flyover bridges being hit.Since the collision between the vehicle and the bridge pier is close to the ground,the bridge pier is prone to shear damage in this case.In response to this phenomenon,in recent years,many scholars have conducted a series of experimental studies on the vehicle impact problem of reinforced concrete(RC)columns,to explore the mechanism of shear failure of RC columns when they are subjected to near-ground horizontal impact loads,and to avoid shear failure.method of destruction.There are also many experts and scholars who have studied the impact resistance of CFST columns,but the research on CFST columns is mainly focused on replacing steel bars in RC columns with steel tubes,and then studying their dynamic responses under impact;There are few studies on the impact performance of steel tube reinforced concrete members,especially the shear damage of steel tube reinforced RC columns when they are impacted near the ground.In view of the above problems,this paper carried out an experimental study on the impact loading of the steel tube reinforced RC column near the ground.In order to simulate the impact of column-like components more realistically,the existing test methods and test devices are investigated in this paper,and it is found that the existing test devices have certain defects.Therefore,in order to simulate the problem of lateral impact near the ground end of column-like components as realistically as possible,a large-scale rigid tie-rod pendulum impact test device was developed in this paper to complete the test;the device combines the current small-tonnage rigid tie-rod pendulum and The advantages of the flexible tie-rod pendulum are the characteristics of large hammer head mass,flexible and variable hammer head height,high impact speed,and good directional stability.Based on this test device,the near-ground horizontal impact loading test of three cantilevered columns was completed.The test columns were ordinary RC columns,built-in steel pipe reinforced RC columns(steel pipes were arranged in steel cages),and external steel pipe reinforced RC columns(steel pipes)Wrap the RC column),carry out the repeated impact test with increasing impact energy on the three columns until the column is greatly damaged,and record the whole process of the test with a high-speed camera;the impact force,displacement and reinforcement of the columns are also recorded in the test.Strain,etc.are measured by line.The experimental results show that the impact force of the steel pipe reinforced RC column is more than twice that of the ordinary RC column,and the lateral stiffness of the steel pipe reinforced RC column is higher than that of the ordinary RC column,and the damage is lower than that of the ordinary RC column at the same impact energy.ANSYS/LS-DYNA display finite element software was used to simulate the test,and the validity of the nonlinear finite element model was verified by comparing the test results;then based on the verified model,parameter analysis was carried out to study the impact energy and the height of the impact point Influence on impact properties of steel pipe reinforced RC columns.The results show that due to the protective effect of the steel pipe,the shear damage of the RC column with the external steel pipe is much smaller than that of the RC column with the built-in steel pipe;for the steel pipe reinforced RC column,the lower the impact point,the greater the shear damage of the column.