Collapse Analysis of Double-column RC Girder Bridge Under Rockfall Impact
Aiming at the serious threat of rockfall impacting girder bridges in mountainous area,refined numerical simulations on the collapse of a typical double-column reinforced concrete(RC)girder bridge under rockfall impact were performed by the software LS-DYNA.Firstly,the finite element(FE)model of a prototype girder bridge under rockfall impact was established with considering the pile-soil interaction and bond-slip relationship between reinforcement and concrete.Then,the reliability of adopted material constitutive model,mesh size,contact algorithm and their parameters was validated by comparing with a horizontal impact test on double-column RC bridge pier.Furthermore,Wenchuan Chediguan Bridge Collapse Accident was numerically reproduced,and the collapse process of the girder bridge under rockfall impact was analyzed.Finally,the influence of rockfall mass,impact velocity and impact height on the dynamic responses and damage of girder bridge was discussed.The results show that:the collapse process of girder bridge under rockfall impact can be divided into impacted pier destruction,adjacent pier destruction and girder falling,in which the impacted pier destruction is he critical factor;neglecting the pile-soil interaction and bond-slip relationship between reinforcement and concrete,results in the smaller predicted cross-section responses of piers,and thus overestimates the rockfall impact resistance of girder bridge;compared with the impact height,rockfall mass and impact velocity have a more significant influence on the dynamic responses of impacted pier and overall damage degree of girder bridge.
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