Fatigue Stress Spectra and Reliability Evaluation of Short- to Medium-Span Bridges under Stochastic and Dynamic Traffic Loads

Abstract

This study presents a novel approach to simulating the fatigue stress spectra of short- to medium-span bridges under stochastic and dynamic traffic loads. The stochastic traffic load is simulated based on the weigh-in-motion (WIM) measurements of a heavy-duty highway bridge in China, and the dynamic effects are modeled using a vehicle-bridge coupled vibration system. An interpolation RSM is used to approximate the effective stress ranges of a bridge with respect to road roughness conditions, gross vehicle weights, vehicle configurations, and driving speeds. The RSM provides a platform for an efficient spectrum simulation of bridges under stochastic and dynamic traffic loads. A case study of a simply supported T-girder bridge demonstrates the effectiveness and efficiency of the proposed approach. The proposed computational framework provides an effective approach for simulating the fatigue stress spectra for short- to medium-span bridges with WIM data. However, the efficiency of the approach depends on the number of intervals of driving speed and gross vehicle weight in the interpolation RSM. Additionally, overloading control has a considerable influence on the probability density of the high-amplitude stresses in the fatigue stress spectrum. Even a relatively high overloading limit value will considerably increase the fatigue reliability of a bridge. In addition, the numerical results provide a theoretical basis for bridge deck retrofitting and truck overloading control measures.