Dynamic Reliability of Cable-supported Bridges Under Moving Stochastic Traffic Loads

Abstract

The traffic load has grown significantly in recent years, which could pose a threat to the service safety of existing bridges. Thus, evaluating the actual traffic load effects on bridges using actual traffic data is an urgent task. This study presents a framework for extrapolating maximum dynamic traffic load effects on long-span bridges using site-specific traffic monitoring data. The framework involves traffic-bridge interaction analysis and probabilistic modeling of extreme values. The weigh-in-motion measurements of a heavy-duty highway were utilized to simulate stochastic traffic loads. Case studies of two long-span cable-supported bridges based on weigh-in-motion measurements were undertaken to demonstrate the effectiveness of the proposed framework. It was concluded that Rice’s level-crossing approach can capture both the dynamic and probabilistic characteristics of traffic load effects, and thus provides a reasonable extrapolation. The amplification factors for the cable-stayed bridge and the suspension bridge are 5.9% and 3.6%, respectively. For a longer-span bridge, the dynamic effect for extrapolation is weaker, but the effect of traffic volume growth seems more significant.