Abstract：Research purposes:With the fast development of China＇s modernized industry，the phenomenon of vehicle overload becomes popular and it would damage the bridge and weaken the bridge＇s durability，resulting in reduction of the load bearing capacity of the bridge in different degrees，and even endangering the bridge＇s safe operation． Taking the low － tower cable stayed bridge as the engineering background，taking the finite element software MIDAS /CIVIL as the analysis means and taking the fatigue reliability theory as the base，the finite element simulation analysis of the influence of the vehicle overload on the load bearing of low － tower cable stayed bridge was made and the research was done on the influence of vehicle overload on the fatigue reliability of the stay cable．
Research conclusions:(1) From the finite element calculation of the stress range and fatigue of the stay cable under the different loads，it can seen the fatigue reliability of stay cable decreases to about 0． 8 under the live load of 120 t．(2) The influence of the overload vehicles on the bridge structure should be fully realized and it should be considered in design to improve safety and enhance the service life of bridge．
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［2］赵国藩． 高等钢筋混凝土结构学［M］． 北京: 中国电力出版社，1999．
Zhao Guofan． Advanced Reinforced Concrete Structures［M］． Beijing: China Electric Power Press，1999．
2012, Vol. 29 
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