考虑结构劣化和荷载历史的既有桥梁承载力更新

The load bearing capacity of existing bridges can be more realistically assessed using a method that assesses the capacity based on load history information using structural time-dependent reliability theory. The capacity degradation is described by a fully-correlated stochastic process and the loading history is described by a statistically independent stochastic process. An explicit formula is presented that takes into account the capacity deterioration and the uncertainties associated with the load history. Illustrative examples demonstrate the accuracy of this method. The method is then used to analyze the effects of loading history, with and without consideration of the resistance degradation, on the capacity assessment of existing bridges. Larger loading histories give a larger updated bridge bearing capacity. However, if the resistance degradation is ignored, the bearing capacity will be greatly overestimated, resulting in unsafe evaluation results.