Spatial probabilistic analysis on a prestressed concrete slab bridge based on modified chloride diffusion coefficient model subject to chloride-induced corrosion

The performance of Prestressed Reinforced Concrete (PRC) structures degrades with time subject to chloride-induced corrosion. Corrosion could result in reduction of area of prestressing steel, cover cracking and even spalling due to corrosion products. This finally leads to a decrease of structural load-carrying capacity. Many factors influence corrosion induced by chloride ion, such as time, ambient humidity, temperature and loading. This paper proposes a modified chlorides diffusion coefficient model which considers the effect of time, ambient humidity, temperature and compressive stress. A spatial time-dependent reliability model is developed to predict probability of corrosion initiation over 100 years. Probabilistic evaluation of time to corrosion initiation has then been carried out for an aging PRC slab beam bridges exposed to aggressive environment. It is indicated that the probability of corrosion initiation for spatial variabilities considered with a scale of fluctuation of 3.0 is 1.06 times higher than that predicted for non-spatial. It is found that the probability of corrosion initiation for RH=90% is 12% higher than that predicted for RH=80%. It is also observed that a higher temperature will result in an increase in corrosion initiation probability. It is found from calculated results the spatial variability of parameters is important for reliability analysis.