The Influence Of The Impactor Stiffness On The Dynamic Response Of Circular Concrete-filled Steel Tube

As an important part of the high-speed railway network,the high speed railway station is faced with the risk of the train derailment,and the concrete-filled steel tube is a type of load-bearing component widely used in the high speed railway station.Therefore,it is of great significance to study the dynamic response of the concrete-filled steel tube under the impact of the train.Due to the impact body tends to undergo elasto-plastic deformation during the actual impact,this paper takes the train derailment to impact the concrete-filled steel tube of the station room as the research object,and carries out the drop hammer impact test under the action of the non-rigid impact body.Based on the test results and the finite element analysis,and the bilinear stiffness of the train under the impact of the impact is built on the basis of the test results and the finite element analysis.The influence of impactor stiffness on dynamic response of CFST columns is studied.The main results of this paper are as follows:?1?The experimental study on the lateral impact of circular concrete-filled steel tube was carried out.A group of rigid impact bodies and three groups of non-rigid impact bodies were selected and contrasted,which obtained force time history curve and displacement time history curve of the components.The test results show that the force time curve of the rigid body can be divided into peak,platform and descending section,while the force time curve of non-rigid body is divided into weak stiffness,strong stiffness and descending section.The impact force of the weak stiffness section of the non-rigid body is obviously smaller than that of the rigid body?42.9%⁷4.3%?,and the impact value of the rigid body is almost equal to the impact platform of the rigid body?basically equal?.Also,it indicates that the deflection values of the components are from 24.8%to 37.2%of the rigid body impact because of the energy dissipation of the non-rigid impingement body,indicating that the rigid impact body is conservative.?2?The finite element model of the concrete-filled steel tube under the impact of rigid and non-rigid body is established and compared with the force time history curve and displacement time history curve got from the experiment,which verifies the validity of the parameters of the finite element model.?3?A mass-spring model is established for the bilinear stiffness?K₁ is the initial stiffness and K₂ is near infinity?.The force time history curve is compared with the results,and the validity of the model is verified.?4?Using the model and combining the stiffness of the actual high speed train?K₁?,the finite element analysis of the behavior and rigid impact of the concrete-filled steel tube was carried out.The results show that when the bilinear stiffness is applied,the impact force of the weak stiffness section of the non-rigid body is obviously smaller than that of the rigid body,and the impact value of the rigid body is almost equal to the impact platform of the rigid body.The displacement of concrete-filled steel tube is much less than that of rigid body,which is only 47.5%of the impact of rigid body under the same condition.At the same time,due to the large amount of energy absorbed by the spring deformation,the energy dissipation of the component is only 54.5%of the impact of the rigid body.The results show that the rigid impact body without deformation capacity is too conservative to simulate the train impact process.?5?The dynamic response law of train members under impact is analyzed.The results show that the maximum displacement value increases linearly with the decrease of the K₁value,and the energy consumption increases linearly with the decrease of K₁,and increases linearly with the maximum displacement.The more energy dissipation is,the closer the dynamic response of the component is to the impact of rigid body.For rigid body impact,the response of the component is often analyzed by the comparison of the impact force platform value.However,for the non-rigid body impact,it should be considered according to the energy absorption angle.