Abstract: Based on the equivalent principle for static response of bridge，car distribution was determined according to the lane load of current specification，in the engineering background of Chongqing Qingcaobei river bridge． Car-bridge coupling analysis was then performed under various running speeds and road roughness． And the impact coefficients of various correlative programs of the bridges were obtained． The adaptability of the impact coefficients of the current specification was evaluated． The results show that impact coefficients of current specification are inclined to be dangerous for certain member forces of long-span suspension bridge．

Key words: long-span bridge, impact coefficient, car-bridge coupling

摘要： 以重庆青草背长江大桥为工程背景，基于桥梁静力效应等效的原则针对规范车道荷载逆向反推得到桥上车辆 的布置，开展不同车辆速度、路面粗糙度情况下的车辆-桥梁耦合振动分析，得到桥梁各关注项目的冲击系数，评价 现行规范冲击系数取值的适应性。研究结果表明:现行规范中的冲击系数取值对于大跨度悬索桥的部分内力效应 偏于不安全。

关键词: 大跨度桥梁, 冲击系数, 车桥耦合