Author(s)

LUIS ROMERA, SANTIAGO HERNÁNDEZ, AITOR BALDOMIR, FELIX NIETO

Abstract

Many footbridges have been built in the recent past and there is a trend to design them as very flexible structures. This increased flexibility has had some undesired effects as unexpected vibrations under pedestrian loads, mainly in lateral direction, had occurred in several footbridges in different countries; amongst them those happening on the Millennium Bridge in London attracted a lot of publicity. As a consequence the behavior of people walking along this construction and the dynamic load produced is already known more precisely and it is better understood now. A conclusion extracted is that not only vertical forces but also lateral component of pedestrian load need to be taken into account in the analysis. In this paper a study carried out to an innovative three span stress ribbon footbridge is presented. First, the structure is described narrating summarily the construction steps to make clear the need to consider nonlinear analysis to identify the footbridge geometry at the end of the construction, which is the baseline to obtain the eigenfrequencies. The objective of the work in this paper was to evaluate the lateral vibrations of the structure under pedestrian loads and for doing that several scenarios of people walking along one span or the full length of the footbridge and different definitions of the dynamic loads including vertical and lateral force components were considered.

Keywords

footbridges, stress ribbon structures, nonlinear analysis, pedestrian loads, modal analysis, footbridges vibrations, pedestrian comfort