Recent advances in our understanding of vertical and lateral footbridge vibrations

An extensive amount of research into pedestrian-induced footbridge vibrations has been undertaken over the past 15 years, mainly as a result of the vibrations that plagued the opening of both the Léopold-Sédar-Senghor and Millennium Bridges in Paris and London respectively. Research has focused on evaluating either the vertical or lateral vibrations caused by pedestrians, as it is generally accepted that these two forms of vibration have distinct driving mechanisms. The results of this research have lead to the establishment of several national and international standards and methodologies for the evaluation of footbridge vibrations. Nevertheless, the calculation of the expected vibrations using the various standards and methodologies often provides widely varying results. Furthermore, several important aspects of the vibration mechanisms have generally been ignored or misunderstood. In this paper, a brief review of the recent advances in our understanding of crowd-induced footbridge vibrations is made, with focus on clarifying important aspects of the vibration mechanisms and bringing to attention the relevance of treating human induced loading in a non-deterministic manner.