peer reviewedThis work studies an unusual way to improve comfort of a footbridge with cables. Cables can be seen as a means
of dissipating energy in a structure. This complementary source of dissipation does not prohibit resonance from
taking place, but it is a way to limit vibrations and to impede vandals’ actions. This study is illustrated with
measurements realized on a specific footbridge. This structure is a metallic arch characterized by a first natural
frequency of 3.2Hz and a corresponding damping ratio of 0.55%. Intolerable accelerations (around 6m/s²) are
easily reached when an ill-intentioned person is bouncing at an appropriate frequency. After installation of a
single cable at a suitable location in the structure, the measured damping ratios are almost doubled and the
maximum accelerations at resonance are reduced by 30%. With three cables on the footbridge, the damping ratio
becomes significantly nonlinear: it reaches up to 3% for low amplitude oscillations, but drops down to 1% for
moderate to high amplitudes. For higher accelerations, it does not seem to depend on the number of cables.
According to these observations, a notable effect of cables is to reduce the maximum acceleration, but the main
effect is to prolong the transient phase and to make the resonance frequency hardly identifiable by vandals