Life-cycle performance of RC bridges exposed to vehicle overloading and corrosion-fatigue degradation

Overloading from overweight vehicles poses significant threat to bridges. The coupled interaction of overloading-induced fatigue and chloride-induced corrosion causes corrosion-fatigue degradation of bridges and severely affects bridge safety, long-term performance, and service lives. Pertaining to this, the current research explores the combined effect of corrosion and overloading-induced fatigue on the life-cycle performance of a RC T-girder bridge. Developed framework for this purpose incorporates vehicle bridge interaction (VBI) algorithm through a coupled dynamic analysis scheme integrating finite element (FE) model of the bridge developed in OpenSees with a fatigue truck model created in MATLAB. To capture nonlinear behaviour of the bridge girder under overloaded trucks, grillage modelling with linear and nonlinear elements for the deck-girder system is done in the FE model. As par the observed corrosion-fatigue degradation, several degraded FE models of the bridge are developed at various time instances along its life span. Results show a sharp decline in bridge performance beyond 50 to 60 years of age (depending on underlying uncertainties) that causes rapid increase in bridge response under traffic load beyond that point. This degradation makes the bridge to reach either the serviceability limit state or ultimate failure criterion under traffic much before its intended service life.