Time-dependent reliability assessment of aging structures considering stochastic resistance degradation process

Reasonable assessment of structural resistance degradation and reliability is the premise of formulating targeted maintenance strategy of aging structures. In this paper, a Gamma-based stochastic resistance degradation model is developed by incorporating the spatial degradation into a non-stationary degradation process. Then, based on the hazard-function-based reliability analysis method, a novel reliability assessment approach of aging structures is proposed considering stochastic degradation process of resistance. In addition, a simple case analysis of concrete bridge is used to illustrate the application of the proposed method. The case analysis results show that the resistance degradation presents great discontinuities in time and large spatial variability in the middle and later service period of structures. After 50 years of service, the resistance degradation coefficient considering the effect of spatial degradation process is 13.8% lower than that without consideration in this case. Parametric analyses show that an increase of the shape and scale parameters of mean resistance degradation model will significantly increase the cumulative failure probability of structures. This conclusion is also applicable to the non-stationary vehicle load effect model of case bridge. Additionally, ignoring the spatial variability of resistance degradation and the non-stationary nature of the vehicle load effect will overestimate the reliability of aging structures.