车辆撞击下圆柱桥墩动态响应影响因素分析

Parametric Study on Dynamic Response of Cylindrical Bridge Piers under Vehicle Collision

随着交通量的高速增长,车辆撞击桥墩事件发生概率大幅提高,造成的危害也日趋严重。目前,我国车辆-桥墩设计撞击力为1000KN,远低于美国现行标准2670KN。采用有限元模拟的方法,研究了软冲击下圆柱桥墩的变形失效模式和侧向撞击力影响因素。结果表明,动态冲击下桥墩将发生双剪切失效模式。墩顶边界条件、墩顶压力和车辆质量三个因素对侧向撞击力影响较小,但随着车辆撞击速度的增大,侧向撞击力将大幅提高。从桥墩防撞安全角度来说,设计合理的桥墩结构以提高吸能性能是关键。另外,动态撞击下产生的实际撞击力峰值达到13000KN,远超美国现行标准。因此,设计撞击力有必要大幅提高。

With traffic rapidly increasing, the probability of vehicle collision with bridge piers rises greatly which induces more serious hazard. Nowadays, Chinese design standard of vehicle-pier collision force is 1000KN, much smaller than the USA 2670KN. Using finite element simulation, deformation and failure modes of cylindrical bridge piers and influential factors of lateral impact force of those under soft impact were investigated. It was revealed that double-shear failure mode would occur in the piers under lateral impact load. In addition, such parameters as the top boundary conditions, the axial load level and the vehicle’s mass have little influence on transverse impact force. Otherwise, transverse impact force would increase rapidly with vehicle’s velocity increasing. As far as anti-collision protection of bridge piers was concerned, it is the key to design optimal pier structures to improve its capacity of energy absorption. In addition, the peak dynamic impact force would achieve 13000KN, much larger than the USA standard. So, it is very necessary to suggest a sharp rise for collision force standard.