Time-Dependent Reliability Analysis Of Existing RC Highway Bridges

In this article, several durability evaluation methods of RC bridge are introduced. And the method based upon reliability theory is the emphasis. The basic principles of reliability theory and the basic calculation methods of reliability index: JC method and Monte Carlo method are detailedly introducedIn probabilistic limit state design of RC bridge, the resistance of the bridge is disposed as one stochastic variable. In actual environment, by the reasons of concrete carbonation, steel corrosion, load variation, the resistance of RC bridge will be degraded. The resistance of the RC bridges should be considered as one stochastic process.So the reliability evaluation of RC bridge is a time-dependent reliability problem.In this article, three methods to solve this problem are introduced.In the aspect of resistance degradation, based on the studies of concrete durability by the predecessors, one resisting force model is established,and the calculation formula of the resistance parameters are deduced.Based upon the model establishment of the resistance and the load effect, and the comprehending of the reliability theory, one program used to calculate the time-dependent index of the bending member is compiled by MATLAB language.Through one example, the time-dependent reliability index of the bridge is calculated by the program.The calculation results of the time-dependent reliability index based on the three methods are analysed.The changes of the time-dependent reliability index are analysed by changing the segments of the design reference period. Finally, the factors affecting the time-dependent reliability index of RC bridges are also analysed.