Parametric study of the apparent modal parameters of crowd-footbridge systems

Resumo

The modal parameters of footbridges are time-variant as pedestrians walk along them, resulting in a new dynamic system comprising the isolated structure and the walking persons. This phenomenon is known as human-structure interaction (HSI) and is particularly significant for lightweight footbridges, where the effective damping ratio of the combined system is significantly higher than that of the isolated structure. This paper proposes an analytical-numerical approach to address the effects of HSI on the modal parameters of the coupled system. The effective damping ratios and natural frequency are determined by solving the eigenvalue problem of a two-degree-of-freedom mass-spring-damper system, with one degree of freedom representing the isolated structure and the other representing the equivalent model of the walking persons. The obtained results are compared with experimental measurements from the literature, illustrating the effectiveness of the proposed approach while also demonstrating its computational cost-effectiveness in comparison to existing methods.