Time-Dependent Reliability Analysis of RC Bridges Considering Shrinkage, Creep, Resistance Degradation, and Vehicle Load Flows

Abstract

Due to concrete shrinkage, concrete creep, resistance degradation, and vehicle load flows, the long-term performance of reinforced concrete bridges exhibits time-varying characteristics. The vehicle-borne process is a nonstationary random process, which interacts with concrete shrinkage, concrete creep, and resistance degradation to cause constant changes in bridge internal force and deformation, further, bridge dynamic reliability occurs. This study presented a reasonable method for calculating the time-varying reliability of simply supported girder bridges under the effects of traffic loads and shrinkage creep. Stochastic truck-load models were simulated based on site-specific weigh-in-motion measurements, then the internal forces of the bridge were calculated when the mean value of vehicle-mounted effects increases by 1% per year. Considering the resistance degradation and load effect increase, the reliability of the RC bridge in serviceability limit state and capacity-carrying ultimate state were analyzed using first-passage probability method and Monte Carlo method, respectively. The accuracy of the proposed method was verified by comparison. The evaluation results show that the failure probability including shrinkage and creep has increased significantly; creep is affected by the bridge span and the number of main girders, and the reliability assessment results are safer for bridges with smaller spans.