Set of equations to estimate the modal parameters of the human-footbridge coupled system

Resumo

Human–Structure Interaction (HSI) refers to the dynamic interplay between pedestrians and footbridge structures, forming a coupled mechanical system that may be represented by a single degree of freedom model (SDoFM) with modal parameters that differ from those of the empty footbridge. This study aims to present fitted equations to estimate the modal parameters of the coupled system, derived from numerical simulations emulating free vibration tests of occupied footbridges. Structural responses are evaluated using three methodologies, under pedestrian induced walking loads: (i) solving the coupled multi-degree-of-freedom model (MDoFM) of the footbridge–pedestrian system; (ii) solving the SDoFM of the coupled system, using the proposed equations; and (iii) solving the SDoFM of the empty footbridge, disregarding HSI effects. Results show neglecting HSI leads to significantly higher vibration amplitudes than those displayed by the coupled systems analyses, while MDoFM and SDoFM yield similar responses, demonstrating the practical relevance of the proposed HSI-SDoFM approach.