Tuned mass dampers sensitivity in footbridge vibration control

Being characterized by low frequencies in the range of interest of pedestrian pacing loads, low damping and reduced specific masses, long span and slender footbridge structures are commonly prone to important dynamic responses.

In order to mitigate pedestrian induced vibrations auxiliary devices characterized by a mass-spring-dashpot system, commonly known as Tuned Mass Dampers or simply TMDs, are often installed into these structures. Their goal is achieved by a suitable choice of their main parameters, commonly expressed in terms of mass, stiffness damping and intrinsic sensitivity that allows to transfer some structural vibration energy to the TMDs and then to dissipate it by means of their dampers.

The aim of the present paper is to illustrate the results of recent experimental activities performed at FIP Industriale Testing Laboratory in Italy on full-scale TMD units now installed on a recently opened footbridge over Po River in Turin, as well as at proposing a testing protocol for the tuning operations, which is at the current time unavailable.