Fatigue reliability of deteriorating prestressed concrete bridges due to stress corrosion cracking

Abstract

In this paper, an analysis framework is presented to develop a relationship between fatigue reliability in a prestressed concrete bridge and the progress of stress corrosion cracking (SCC) in prestressing steel. The fatigue limit state uses a cumulative damage model for prestressing steel wires, which is a function of both stress range and minimum stress. The SCC model takes into account varying degrees of material susceptibility, stress regimes, and environmental conditions and is structured around three stages: initiation of micro-cracking, propagation, and macro-crack instability using linear elastic fracture mechanics. The framework is an overall time-dependent analysis of the safety against fatigue of a prestressed concrete bridge. It involves a stochastic analysis of the evolution of prestressing wire corrosion as a function of time and a time-dependent probabilistic analysis of the fatigue reliability of the prestressed concrete bridge suffering a certain degree of deterioration. The uncertainties involved in the fatigue model, the SCC model, and traffic actions are considered. The updating of uncertainties is simplified by considering a limited number of classes representative of the severity of SCC exposure. The framework is applied to three deteriorating highway bridges.Key words: fatigue analysis, prestressing strands, stress corrosion cracking, reliability assessment, prestressed concrete bridges, deterioration.