Research On Damage Of Unbonded Prestressed Precast Segmental Bridge Pier Under Vehicle Collision

With the advantages of fast construction speed,low labor cost and little influence on the surroundings,precast assembly technology has been widely used in the world,among which,a lot of research has also been done towards precast segmental pier.With the rapid development of urban traffic,more and more traffic accidents emerge,and the vehicle collision accidents on bridge pier also become more frequent.Therefore,it is significant to study the anti-collision performance of piers.In this paper,studies on the dynamic responses and damage analysis of unbonded prestressed precast segmental bridge pier under vehicle collision is carried out.The main contents are as follows:(1)The feasibility by using the software of LSDYNA to simulate vehicle colliding on precast segmental pier is verified by establishing a numerical model of pendulum impact test.The influence of colliding vehicle’s type and speed,and structural prestressing forces on the dynamic responses and damage of precast segmental pier is studied by numerical simulation.It is found that:the time history of collision force induced by trailer is different from that of pickup truck and normal truck,and the damage of the precast segmental pier induced by trailer is more serious;the change of the prestressing force has little effect on the dynamic responses and damage of the precast segmental pier,but with the increase of the prestressing force,the level of the collision force and the maximum displacement after collision slightly decrease;compared with the low collision speed,as the trailer collides the pier with higher speed,both of the collision force and the maximum segmental displacement all increase significantly.(2)A comparison between the anti-collision performance of single and double-column unbonded prestressed precast segmental pier is taken,and further damage analysis of the capping beam and pier is evaluated.By numerical simulation,it is seen that the damage of capping beam under the collision is mainly on the joint of capping beam and pier,and near the reserved hole.The pier damage is mainly concentrated on the collided position,the joint of connecting segments and the base of pier.The damage of single and double-column piers is evaluated by calculating the residual bearing capacity.It is found that the anti-collision performance of double-column precast segmental pier is lower than that of single-column one.(3)In order to improve the anti-collision performance of unbonded prestressed precast segmental pier,the improvement effect of the CFRP material ratio and the hybrid reinforcement on the anti-collision performance are explored.The calculation results indicate that:CFRP material can effectively reduce the collision force on precast segmental pier,and reduce the maximum segmental displacement after collision;by means of hybrid reinforcement,the energy dissipation and self-centering capacity of precast segmental pier can reach a desired balance.According to the study cases in this paper,when the hybrid reinforcement ratio r _H=0.75,the anti-collision performance of the pier with a high level energy dissipation and self-centering capacity,is better than other ones.