Considering Soil - Structure Interaction Of The Railway Bridge Height Limit Of The Protective Frame And Ultra-high Vehicle Collision Dynamic Response Analysis

To protect the safety of the railway bridge, height limit signs and high limit protection frame should be installed on the road which under the railway bridge or culvert according to Regulations on Protection of Railway Transport Safety in recent years. However, it is of common occurrence that collision occurred between over-high vehicle and high limit protection frame because of the unreasonable design of the high limit protection frame or the driving errors. The collisions not only caused huge economic losses, but also a serious threat to the safety of the railway bridge. Therefore, the study of collision mechanism between over-high vehicle and high limit protection frame has the great practical significance and application value for the design and impact resistance ability of the high limit protection rack.In this paper, the collision process of over-high vehicle and high limit protection frame under different cases is simulated considering the soil - structure interaction using nonlinear software of ANSYS/LS-DYNA. The collision mechanism is studied from the collision region, size of impact force, collision time, energy conversion and get the following main conclusions:(1) The initial velocity and quality of the impactor have great influence on the impact force. The maximum impact force increase as the initial velocity increase and approximately direct proportional to the initial velocity; both the local impact force and the average impact force increase as the initial velocity increase but not proportional to the initial velocity. Also, the local impact force and the average impact force increase as the quality increase; however, the maximum impact force decrease as the quality ratioα(vehicle quality / protection frame quality) increase. The influence of initial velocity and quality on impact force should be taken into account when determine the design value of the impact force in the design.(2) After considering the soil - structure interaction, the maximum impact force, local impact force and the average impact force all increase. The increase rate of maximum impact force is largest, reached about 20%, and the increase rate of the local impact and average impact force is smaller, reached about 5%. Meanwhile, with the initial velocity and quality of the impactor increase, the increase rate of the maximum impact force, the local impact force and the average impact force gradually increase.(3) The increase of initial velocity and quality of the impactor will both make the interaction time increases, and the interaction time decrease after considering soil-structure interaction in the conditions of the same initial velocity and quality.(4) Most of the energy of the system is transformed into the plastic deformation energy and the kinetic energy of the protective frame is very few compared with its internal energy.(5) The damage of the high limit protection frame occurs mainly in the upper beams and the support area and its dynamic response showed significant regional, which reflected in the structure: the dynamic response is gradually become weaker from the middle of the beam to the bottom of the column.