An efficient approach for considering the effect of human-structure interaction on footbridges

摘要

Mainly because of the infamous incident with excessive vibrations of the London Millennium Bridge, the behavior of lively footbridges has been thoroughly studied lately. The liveliness of such bridges is strongly connected to various interaction effects between the pedestrians and the bridges. One such effect is the variation in the modal properties of the bridge, due to the presence of a crowd. In theoretical models of such systems, this is often accounted for by describing each pedestrian as a spring-mass-damper system, having its own dynamic properties, producing a time-variant system. A major drawback with models of this kind is that the computational time increases rapidly with the size of the system, i.e. for a larger crowd. Therefore, with the objective to reduce the computational time needed, this study focuses on describing vertical human-structure interaction by means of a simplified model. The paper describes a new methodology for taking this effect into consideration when predicting the dynamic response of a footbridge, subjected to human-induced, vertical loads. The method is used to predict the vertical bridge deck accelerations of a simply supported footbridge. The predictions produced by the proposed methodology are compared with existing models and it is shown that for certain bridges, it produces an accurate approximation at a significantly reduced computational cost.