Performance of single pedestrian load models in predicting dynamic behaviour of flexible aluminum footbridges

Their high strength-to-weight ratio and slenderness can make aluminium pedestrian bridges lively structures. The large amplitude of vibrations may reduce their serviceability under operational loads and may drive the dynamic design over the static one. In order to properly design aluminium bridges, it is important to define suitable load models to estimate structural response under human induced vibrations. The pedestrian force is commonly modeled in terms of periodic ground reaction forces (GRFs) on rigid surfaces, depending on weight and pacing frequency of the pedestrian, and the GRFs so obtained are approximated through Fourier series with dynamic load factors corresponding to the harmonics. However, most of these models have not been sufficiently verified from experimental and field measurements of bridge response under pedestrian excitations. The scope of this paper is to provide an overview of the periodic load models and their performance in predicting the response of footbridges. Predictions by the existing analytical load models are compared with field measurements conducted on a flexible aluminum bridge, and key observations regarding the applicability of existing models to predict the vibration behaviour of these bridges is reported.