Vibration serviceability of footbridges under human-induced excitation : a literature review

http://michael.friswell.com/PDF_Files/J108.pdf

A review of robust optimal design and its application in dynamics

The dynamic response of suspension footbridges to pedestrian-induced excitations and its passive mitigation, via multiple tuned mass dampers (TMDs), are investigated. First, the nonlinear equations of motion are obtained assuming finite planar motions of the suspension bridge. A suitable approximate version of the equations of motion is shown to be in agreement with existing theories and its linearization is then employed in the structural dynamics analyses. A Galerkin discretization is exploited to calculate both the free and forced dynamic response towards the design of the vibration control system. First, the leading characteristics of the bridge dynamic response are outlined. Resonant vibrations induced by the passage of pedestrians are shown to be effectively reduced using viscoelastic TMDs. As the frequencies of the lowest two modes in suspension footbridges can be very close in the proximity of the crossover phenomenon, three different design scenarios are considered: below, near and above the crossover. In particular, the influence of these scenarios on the passive control architecture is investigated.

Mitigation of Pedestrian-induced Vibrations in Suspension Footbridges via Multiple Tuned Mass Dampers

Effects of tuned mass dampers on random response of bridges

This chapter deals with structural vibrations caused by human body motions. Of great importance are vibrations induced by rhythmical body motions such as 


walking


running


jumping


dancing


handclapping with body bouncing while standing


handclapping while being seated


lateral body swaying.

Vibrations induced by people

The work described is part of a research programme into ways of reducing pedestrian-induced vibrations of footbridges, the problem being that these vibrations can cause discomfort to the user. The two case studies presented describe one method by which this has been achieved - the discrete tuned vibration absorber. Results show that an absorber with a low mass value (approximately 0.6% of the bridge superstructure mass) can achieve very worthwhile reductions in vibration levels. This effect is, however, dependent on optimum damping and accurate tuning of the absorber and on minimum dry friction in the absorber movement.(a) (TRRL)

R T Jones

Papers

Two case studies in the use of tuned vibration absorbers on foot bridges