基于时变可靠度理论的桥梁状态评估
Condition Assessment of Bridge Based on Time-Varying Reliability Theory

为对某连续刚构桥进行状态评估，结合时变可靠度研究方法，考虑混凝土强度时变效应和预应力筋强度时变效应等因素，建立其时变可靠度模型，通过有限元软件进行模拟分析，采用不确定分析手段，对桥梁的相关统计参数进行抽样，对其连续刚构段进行计算，计算考虑时变因素下的桥梁失效概率并研究时变效应对评估桥梁失效概率的影响，得到设计使用年限内服役时间与可靠度指标之间的关系，对桥梁状态进行评估。研究表明，基于可靠度方法对现役桥梁状态进行评估时，考虑混凝土强度时变效应和预应力筋强度的时变效应计算得到的失效概率曲线斜率均大于不考虑时变效应时的曲线斜率，对桥梁状态预测的结果更为安全。
For the state assessment of a certain continuous rigid-frame bridge, combined with the time-varying reliability research method, factors such as the time-varying effect of concrete strength and the time-varying effect of prestressed tendon strength are considered to establish its time-varying reliability model. Simulation analysis is conducted through finite-element software. Uncertainty analysis methods are used to sample the relevant statistical parameters of the bridge, and calculations are made for its continuous rigid-frame section to calculate the bridge failure probability considering time-varying factors and to study the impact of time-varying effects on the bridge failure probability. The relationship between the service time within the design service life and the reliability index is obtained to evaluate the bridge state. Research shows that when evaluating the state of existing bridges based on the reliability method, the slopes of the failure probability curves calculated by considering the time-varying effects of concrete strength and prestressed tendon strength are both greater than those of the curves without considering the time-varying effects, and the results of bridge state prediction are more reliable.