中文摘要：

由于设计荷载标准的提高和经济发展的需要，超载现象在服役桥梁中普遍存在，是其承载力下降，耐久性降低的主要原因．超载运营导致桥梁在服役期内经受持续高应力作用，其疲劳损伤分析亟待开展．本文基于桥梁荷载的实测资料，结合模拟超载试验研究资料进行统计分析，得到可以反映服役桥梁交通状况的荷载谱．采用线性累积损伤理论，对一座服役期为37年，超载运营期为1年的钢筋混凝土桥梁进行疲劳损伤分析，并与不同跨度铁路桥梁正常运营100年的损伤度进行对比研究，分析了超载运营对服役桥梁使用性能的影响．

英文摘要：

The bridge design code in China is emended and the legal load level is improved according to the traffic development of economy,which cause the existing bridges suffering a popular problem of overloading. Therefore, traffic overloading causes many structure problems and influence the serviceability and security of existing bridges greatly. This analysis on existing highway bridges. In this paper, the vehicle is gained based on the simulated repetitious overloading gives rise to the load spectrum for experiment and fatigue damage highway bridge on-site traffic investigation. Fatigue damage analysis on existing bridge under overloading is developed Miner＇ s theory adopted. The influence of overloading a reinforced concrete highway bridge, the age of whi is discussed based on the damage index of ch is 37 and the overloading period is 1 year. The fatigue damage of this bridge is compared with that of railway bridge, considering the difference of span length. The result is helpful for the performance evaluation of existing bridge exactly.