Dynamic Response Analysis Of A Long-span Cable-stayed Bridge Under Local Collisions

Now long-span cable-stayed bridges are more and more widely used in practical engineering,but at the same time,risk and probability of the bridge-collisions increase,and the consequences of strong collisions are quite serious in most cases,may cause casualties and the collapse of bridges.Therefore the study of the dynamic response of bridges under local collisions and to improve collision resistance has important practical significance.Based on the case of a long-span cable-stayed bridge in ZhuHai,this paper analyzes and studies the nonlinear dynamic response of the single tower model and whole bridge structure under local collisions,and discusses the protection effect of the anti-collision measure selected in this paper.The research work mainly includes the following aspects:(1)Nonlinear dynamic response of single tower model of cable-stayed bridge under ship collision is analyzed.It is verified that simplified impulse load obtained by equal collision time can simulate collisions.The influence of the simulation for interaction of piles and soil and mesh refinement on time history curves of impact forces,collision impulses,energy change during the collision,typical node’s transversal displacements,internal force responses of the piles and local damage of collision areas is studied.(2)Nonlinear dynamic response of the whole model of cable-stayed bridge under impact load is analyzed.It is verified that impulse loads can simulate time history of original impact forces.Stress responses of the cable,displacements and internal force responses of impacted left bridge tower and bridge deck are obtained.The influence of local impact loads on the whole bridge structure is studied,and the simulation results are compared with the static response under dead loads.The influence of the short-term impact loads on structural displacements and stress responses is further analyzed.(3)Nonlinear dynamic response of the cable-stayed bridge with anti-collision cofferdam under ship collisions is analyzed..Time history curves of impact forces,energy conversion,displacements and internal force responses of the bridge tower,concrete damage of collision areas on the bridge tower and plastic deformation of anti-collision cofferdam,etc are obtained.Besides,displacement and stress response of the bridge structure are obtained when impact forces on bridge tower with anti-collision cofferdam are put on the whole bridge.