基于时变因素的桥梁可靠度指标计算

在预应力桥梁服役过程中，桥梁构件的抗力水平可能降低，同时在运营过程中，桥梁的交通量有可能发生增长，考虑这些时变因素的桥梁可靠度是值得关心的问题。本文总结归纳了三种典型的抗力退化模式，以某地交通量观测结果为依据，拟合了其增长函数；建立抗力衰减和荷载增长的时变模型；接着，本文以某现役预应力混凝土桥梁构件为背景，利用蒙特卡罗法模拟计算了考虑时变因素的可靠度指标，讨论了其安全使用年限。

Calculation of Reliability Index of Bridge Based on Time-variant Factor

In the service process of prestressed bridge, the resistance level of bridge members may be reduced. Also in the operation process, the traffic flow of bridge may be increased. It is worth to concern for considering the bridge reliability of these time-variant factors. Three kinds of typical resistance degeneration model are summarized. Based on the observed result of traffic flow somewhere, its growth function is fitted. The time-variant model of resistance attenuation and load increment is established. Taking the bridge members of a prestressed concrete bridge under service as the background, the Monte Carlo method is used to simulate and calculate the reliability indexes considering the time-variant factors. Its safe service life is discussed.