Experimental study on the interference of vortex-induced vibration and transverse galloping for a rectangular cylinder

The interference of vortex-induced vibration and transverse galloping was investigated in the wind tunnel in the case of a rectangular cylinder with a side ratio of 3:2, the short side facing the flow. The tests were carried out in a wide Scruton number range, starting from low values and increasing it in small steps through eddy-current viscous dampers. This study helped understanding the dynamics of the interaction between the two excitation mechanisms, highlighting the transition through different regimes of interference. It was observed that a high value of the mass-damping parameter is required to decouple the ranges of excitation due to vortex-induced vibration and galloping and for the quasi-steady theory to correctly predict the galloping critical wind speed. This conclusion also means that structures or structural elements with ordinary mass-damping properties can exhibit sustained vibrations where they are not predicted by classical theories of vortex-induced vibration and galloping.