The “bang-bang” control law for mitigation of a suspension bridge vibrations due to wind actions

The numerical model of an existent suspension bridge is developed, starting from design specifications, in the finite element code ANSYS. This numerical model, whose accuracy is validated using experimental data collected on the real bridge, is used (a) to evaluate the structural bridge response induced by extreme winds; (b) to simulate the control of the bridge by means of the “bang-bang” control law. This law is applied to semi-active dissipative devices that connects the girder to the towers. The effectiveness of the “bang-bang” control law is compared to other vibration mitigation strategies, and its reliability and applicability is assessed with respect to improvements of the performance of the selected structure. The other control solutions choices belong to either to the semi-active or to the passive type. The wind excitation is considered equivalent to an extreme event, and is applied to the bridge model in the form of a field of three-dimensional turbulent wind. This is not homogeneous in space, and accounts for the presence of the atmospheric boundary layer.