Codifiable probability-based model for footbridges response to random walkers

Abstract

Abstract The response to the transient action of a single pedestrian or a small group of pedestrians is required for the serviceability assessment of human-induced footbridge vibrations. The approach adopted by standards and guidelines is proved to lead to a non-uniform level of reliability. This is in contrast with both the stochastic nature of pedestrian gait parameters and the probabilistic approach adopted by modern structural codes. In this paper, firstly the analysis of peak accelerations is developed according to the Eurocode for a number of simply-supported footbridges, both in vertical and lateral directions. These are shown to correspond to different level of probability of exceedance, that is larger for short-span footbridges and smaller for long-span footbridges. Then, a model for the assessment of the characteristic footbridge acceleration is provided. This is based on the prediction of the basic acceleration, i.e. the response of simply-supported footbridges to single pedestrian crossings, and the application of an acceleration ratio factor for footbridge configurations other than simply-supported.