Incorporating site-specific weigh-in-motion data into fatigue life assessment of expansion joints under dynamic vehicle load

In long-span bridges, expansion joints are essential in accommodating bridge movement under multiple loads. Generally, expansion joints have a shorter lifespan than the bridge, and they should be maintained regularly for their design function. In this paper, an approach is proposed to estimate the fatigue life of modular expansion joints under stochastic traffic load considering the dynamic impacts of vehicle wheels. The proposed approach consists of three steps, namely, the establishment of the stochastic traffic load model, numerical analysis on the expansion joints under dynamic vehicle load, and fatigue life assessment of expansion joints. Expansion joints in a cable-stayed bridge are used to verify the approach. Site-specific weight in motion (WIM) data are collected to establish the stochastic traffic model, and a vehicle-joint interaction analysis scheme is performed to obtain the stress responses. Effects of vehicle velocities, horizontal impact component, surface irregularities, and damping ratios of the expansion joints are investigated. The rupture in a center beam of expansion joints was successfully explained with the fatigue assessment approach, which was due to the loss of sliding spring. Conclusions are drawn to benefit the design and maintenance of expansion joints.

Automated summary

This paper proposes an approach to estimate the fatigue life of modular expansion joints under stochastic traffic load, and validates it using expansion joints in a cable-stayed bridge. The study finds that vehicle velocities, horizontal impact component, surface irregularities, and damping ratios of the expansion joints have an impact on the fatigue life.