Research On Lateral Impact Resistance And Axial Residual Bearing Capacity Of Circular Steel Pipe

The round steel tube is one of the most important components in the field of construction engineering and has been widely used.However,with the frequent occurrence of accidental loads such as terrorist attacks and object impacts on buildings,how to predict and improve the anti-impact performance of round steel tubes has become a current research hotspot.Scholars at home and abroad have done a lot of research on the dynamic response of the round steel tube after lateral impact and put forward the concept of sag model to reflect the section deformation of the round steel tube after impact.However,compared with the actual deformation,the existing sag model of the impact section of the round steel tube has a large error,which needs to be further improved.Under the action of lateral impact,the integral displacement and local deformation of the axially stressed round steel tube will occur to different degrees,and the axis of the tube is seriously deviated from the initial position.There is a large eccentricity between the axis of the round steel tube and the axial load,which makes it change from the axial compression member to the flexural member,leading to a great reduction in the residual axial bearing capacit y and even loss of bearing capacity.Therefore,it is of great academic significance and engineering application value to study the impact section depression model and residual axial bearing capacity of the round steel pipe subjected to lateral impact.In this paper,numerical simulation method is used to study the sag model and residual axial bearing capacity of Q235 B round steel tube at the impact position after it is subjected to lateral impact.The specific research contents are as follows:(1)Based on ANSYS/LS-DYNA,a numerical model of the lateral impact of a round steel tube was established,and a systematic parameter analysis was carried out to investigate the influence of the initial velocity of the hammer,diameter of t he round steel tube,wall thickness,span and impact position on the cross section deformation.The empirical formula of the displacement of the top sag of impact section is established by fitting,and then the reasonable sag model of impact section is put forward.(2)By establishing the calculation method of the residual axial bearing capacity of the round steel tube with fixed ends after impact,the deformation mode after impact is analyzed,and three plastic hinges are formed at both ends of the supporting position and impact position of the round steel tube.The mechanism of residual bearing capacity of round steel tubes is analyzed based on the second order effect.The influence of different parameters on the residual bearing capacity of the round steel pipe subjected to lateral impact was investigated.Finally,by fitting,a formula for predicting the residual bearing capacity of a round steel pipe with two ends of solid support is proposed,and its accuracy is verified.(3)Based on the calculation method of the residual bearing capacity of the round steel tube with hinge ends established in this paper,the deformation mode of the round steel tube after impact is analyzed,and it is found that the round steel tube only forms a plastic hinge at the impact position.The simulation value of the residual bearing capacity of a round steel pipe with hinge ends is compared with the predicted value calculated by the prediction formula of the fixed ends and improved to make it suitable for the prediction of the residual bearing capacity of a round steel pipe with hinge ends after it is impacted.