中文摘要：

为了对人流、车流密集的城市市政桥梁进行合理的抗爆设计和爆炸风险评估，提出了爆炸荷载作用下城市桥梁动态响应与损伤过程分析的数值方法．首先，通过对城市桥梁爆炸风险源的分析，确定城市桥梁可能遭遇的爆炸源类型及爆炸荷载工况．然后，基于大型通用有限元软件ANSYS／LS-DYNA建立桥梁、炸药和空气三者的有限元模型，分别选择JWL（Jones Wilkins-Lee）状态方程与线性多项式状态方程对炸药和空气模型进行定义，选用ALE（arbitrary Lagrange-Euler）算法模拟爆炸冲击波在空气中的传播；通过改变炸药的安放位置和质量，得到爆炸荷载作用下桥梁关键部位的位移响应、Von-Mises应力分布和整个桥梁的破坏形态，并模拟爆炸后桥梁的损伤过程；以Tuler-Butcher损伤累积准则为依据，求得某些指定单元在不同爆炸距离和不同TNT当量下的损伤累积曲线．最后，以一座大型钢桁架拱桥为例说明本文提出的方法的计算过程，其计算结果可作为桥梁抗爆设计和爆炸风险评估的依据．

英文摘要：

In order to obtain reasonable anti-blast design and risk assessment of urban municipal bridges in a densely populated city, dynamic response and damage process analysis method for urban bridges subjected to blast load is proposed in this paper. By analyzing the explosion risk sources of urban bridges, the explosion source types and blast load conditions likely to be encountered by urban bridges are determined. Then, the finite element models of bridge, dynamite and air are established in ANSYS/LS-DYNA software. The dynamite model and the air model are defined by the JWL （Jones-Wilkins-Lee） state equation and linear polynomial state equation, respectively. The ALE （arbitrary Lagrange-Euler） algorithm is used to simulate the propagation of shock wave actuated by explosion. The effects of position and quantity of dynamite on the response of displacement and the Von-Mises stress distribution in the key parts of the bridge are investigated, and then the damage process and failure modes of the bridge are analyzed. Based on the Tuler-Butcher cumulative damage rule, the damage accumulation curves under different explosion distances and TNT equivalence blast loadings of specified elements are obtained. In the end, taking a large-span steel truss arch bridge as an illustrative example, the calculation process of the proposed method in this paper is described. The results of this paper can be used as the foundation for anti-blast design and risk assessment of bridge.