Lateral crowd-structure interaction model to analyse the change of the modal properties of footbridges

In this paper, a biomechanical crowd-structure interaction model is proposed and calibrated in order to take into account the change of the modal properties of footbridges in lateral direction induced by the pedestrian walking action. The model involves two submodels, namely, (a) the pedestrian-structure interaction and (b) the crowd submodels. In the first submodel, a single degree of freedom system, which simulates the behaviour of each pedestrian, is projected on the vibration modes of the structure. Herein, the parameters of the first submodel are estimated experimentally from the results of several pedestrian tests conducted on a real footbridge. For the second submodel, the crowd behaviour is modelled via a multiagent method. The performance of the overall model has been assessed successfully via the correlation between the change of the first experimental lateral natural frequency of another footbridge during a pedestrian test and the numerical predictions provided by the proposed model. Therefore, this model becomes a valuable tool to analyse numerically the change of the modal parameters of footbridges due to the pedestrian-structure interaction.