Dynamic interaction of a vehicle–modulus bridge expansion joint coupled system

Existing approaches for analysing vehicle–modulus bridge expansion joint (MBEJ) systems either neglect bidirectional interaction or incur high computational costs, thus limiting their application in practical engineering. To address these limitations, a novel iterative framework was developed to decouple the system. Based on the geometric characteristics of the MBEJ, a road roughness profile was generated as input for vehicle dynamic analysis. The resulting vehicle responses were then applied to the MBEJ system to determine the centre beam vibrations, which were iteratively superimposed onto the road profile until convergence. The proposed framework was validated, and the results demonstrate that, for the 33 t three-axle heavy-duty truck analysed, rear axles induce significantly larger beam vibrations than front axles, with outer-lane vehicles causing greater vibrations than inner-lane ones. Beam vibrations are strongly influenced by vehicle speed and axle configuration and exhibit an inverse correlation with joint gap width. The dynamic amplification factor for rear axles exceeds that of front axles, decreasing with speed but increasing with gap width. By efficiently capturing bidirectional interactions, this framework offers a practical tool for optimising MBEJ and bridge design.