The paper analyzes that hoop coefficients of the concrete-filled steel tube influence on dynamic response of the railway bridge height limit protective frame under impact load by using ANSYS/LS-DYNA. Change hoop coefficient of the concrete-filled steel tube structure by changing steel tube wall thickness. The result shows that with increase of steel tube wall thickness, the average impact force of protective frame will increase and the displacement and deformation will reduce, and protective frame can resist greater impact load. It will provide the reference for design of railway bridge height limit protective frame.

The purpose of high-limit protection rack under railway bridge is to protect railway bridge, and avoid passing vehicles under railway bridge colliding bridge. The paper discusses dynamic response and energy transfer of two different structures by analyzing the internal force, deformation, displacement and energy transfer of the steel tube and concrete-filled steel tube protection racks in collision. The result shows that the displacement of concrete-filled steel tube protection rack is smaller, and it can bear larger impact force and have good effect of energy absorption.

Collisions between over-high trucks and protection frame for height limit happen frequently, which seriously destroyed the railway infrastructure and affected the road traffic safety. Based on nonlinear software ANSYS/LS-DYNA, the collision process of over-high trucks and protection frame is simulated, and the failure mechanism of protection frame is analyzed respectively from deformation, stress, load etc. Load analysis results indicate that the maximum impact force is approximately direct proportional to the initial velocity, which can be used for choosing the collision load in the design. Stress analysis results indicate that the maximum stress usually occurs in the protection frame crossbar and joint area. Adding the diagonal bracing or increasing the crossbar thickness are the effective methods to improve the impact resistance capability of the protection frame.