Dynamic analysis of a steel footbridge under running pedestrians

The paper presents the studies on the serviceability conditions of a footbridge to be built in Louvain-La-Neuve (Belgium). The preliminary design was performed by the Engineering Company Mc Carré. The 5-span steel footbridge is 54 m long. The central span is supported by two inclined arches. First, the modelling approach for the structure, aimed to determine its modal properties and to spot possible resonant problem under moving pedestrians, is discussed. The finite element model, developed within the ANSYS framework, does not possess any natural frequency in the critical range excited by walking pedestrians but one frequency is in the range excited by running pedestrians. To investigate the bridge response to a running pedestrian, different approaches of analysis are adopted. Harmonic analysis follows indications from HiVoSS 2008. Three models of moving load are adopted in transient analysis, the two load models in Setra 2006 and the model by Racic & Morin 2014. Results highlight the importance of proper consideration to the effect of running pedestrians, and the need for more accurate guidelines.