Response analysis and vibration control of suspension footbridges via tuned mass dampers

The dynamic response of suspension footbridges to pedestrian-induced excitations and its passive mitigation are investigated. The non-linear equations of motion are obtained and the finite-element code FEMLAB is used to solve both the eigenvalue and forced elastodynamic problems. Further, Ritz-Galërkin discretization approach is employed to solve the free and forced conditions for the design of the control system. First, the leading characteristics of the bridge dynamic response are outlined. Then, it is shown that resonant vibrations induced by the passage of pedestrians can be successfully reduced using visco-elastic tuned mass dampers (TMD), whose effectiveness has been proved to hold also with seismic excitations. The validity of the theoretically proposed method is confirmed in the case of an existing structure, the Singapore Suspension Footbridge.