Abstract: The stress state of the bridge pier under the collision of heavy vehicles with different speeds，and the collision mechanism of vehicle and bridge are mainly studied． The simulation analysis of piers and vehicles is carried out on the basis of the general finite element program ABAQUS． The plain concrete three-dimensional entity model is used as the pier model． The nonlinearity of concrete material is fully considered and reinforced steel is calculated with the consideration of liner elasticity． Ordinary steel entity model is used as the vehicle model，without the consideration of the impact on the vehicles in the collision． Simulated analyses which aim at the situation of vertical impact on the pier caused by different vehicles with three different speeds are carried out． Analyses show that the stress of the pier's collision point is firstly increased with the increase of time，and then the stress will decrease when it reaches the maximum value． This characteristic conforms to the plastic destruction law of the concrete． Meanwhile，analyses also show that the higher the vehicle speed is， the larger the stress and displacement of the pier reaches.

Key words: urban bridges, collision, displacement, stress

摘要： 通过研究城市桥梁中当桥墩在重型车辆撞击下的受力状态及车－ 桥的碰撞机理，采用有限元软件ABAQUS 对3 种不同车速车辆垂直撞击桥墩的情况进行了模拟分析。分析表明: 桥墩被撞击位置处的应力先随时间的增加 而增大，达到最大值时，既又随之减小，符合混凝土的弹塑性破坏; 并且车速越大，桥墩局部达到的应力及位移也 越大。

关键词: 城市桥梁, 碰撞, 位移, 应力