Analysis and control of vibrations in a stress-ribbon footbridge

Abstract

This article describes the research work involving the analysis and control of a flexible stress-ribbon footbridge located at the campus of Faculty of Engineering of University of Porto (FEUP). This structure has several natural frequencies around 2Hz which makes it vulnerable to the occurrence of resonance phenomena related to the excitation induced by pedestrians. Some tests performed with students showed that the observed levels of vibration may not be considered excessive according to some design codes. However, this footbridge is regularly subjected to unusual vibrations in the context of current footbridges, which has motivated the implementation of a control system for research purposes. The active control system developed consists of an active mass driver commanded by a controller based on the direct velocity feedback control law. The efficiency of this control system is evaluated in terms of the reduction of the structural response when the footbridge is excited by several types of pedestrian loads. Copyright (C) 2010 John Wiley & Sons, Ltd.