中文摘要：

根据预应力混凝土桥梁的几何尺寸、材料强度和计算模式不定性系数的统计参数,采用蒙特卡洛方法模拟了预应力混凝土梁桥抗弯承载能力和抗剪承载能力的统计参数;在考虑结构构件抗力、恒载效应、车辆荷载效应、横向分布系数和车辆荷载冲击力的随机性的基础上,建立预应力混凝土简支梁桥的抗弯和抗剪承载能力极限状态方程,采用JC方法计算可靠度指标。对一座既有预应力混凝土桥梁进行承载能力可靠性评估并对影响可靠度指标的随机变量（恒载、车辆荷载、横向分布系数、冲击系数）进行了敏感性分析,结果表明：恒载效应的随机性对可靠度指标影响很小,车辆荷载效应、横向分布系数、冲击系数的随机性对可靠性指标影响较大且依次加大。

英文摘要：

Distribution parameters of moment and shear resistance for prestressed concrete girder bridge are developed by simulations using available statistical parameters of geometrical,material properties and model uncertainty.Reliability limit state equations are derived based on the randomness of resistance,dead load,vehicle live load,girder distribution factor and dynamic amplification factor,and reliability index,β,is calculated by JC methods.Case study illustrate the application of the proposed method to the safety evaluation of prestressed concrete girder bridge.Sensitivity analyses are also performed for finding the effects of random variables including dead load,live load,girder distribution factor and dynamic amplification factor on reliability index.It is shown that the uncertainty of dead load has little influence on reliability of bridge,and the uncertainty of girder distribution factor and dynamic amplification factor has more influence on reliability of bridge than that of vehicle live load.