Uncertainty Effects on Lifetime Structural Performance of Cable-Stayed Bridges

This paper investigates the time evolution of the uncertainty effects associated with the different parameters defining the probabilistic structural performance of two existing cable-stayed bridges in Italy. The study is developed by using a general methodology for time-variant reliability analysis of concrete structures subjected to diffusive attacks from external aggressive agents. The time evolution of the probabilistic structural performance is analyzed with reference to proper indicators of the nonlinear behavior. The beneficial effects of prescribed rehabilitation interventions are also taken into account. The effects of each random variable on such indicators for both damaged and rehabilitated structures are quantified and compared by means of suitable time-dependent sensitivity factors. The obtained results show that the relative importance of the uncertainty effects associated with each random variable may vary significantly over time, and that this variation is considerably reduced by the adopted rehabilitation interventions.