Suppressing Wind-Induced Oscillations of Prismatic Structures by Dynamic Vibration Absorbers

The suppression of oscillations of an elastically mounted prism under galloping by a dynamic vibration absorber (DVA) with linear damping and stiffness is investigated. A model considering the dynamic coupling of the prism and the DVA is constructed, with the aerodynamic loads acting on the system represented by a quasi-steady approximation. Based on the coupled nonlinear governing equations of motion, a linear analysis is first conducted to explore the coupled frequency and damping, and the onset speed of galloping in the presence of the DVA. Subsequently, the normal form of the Hopf bifurcation for the coupled system near the onset of galloping is derived to characterize the type of instability (supercritical or subcritical), while evaluating the effects of the DVA parameters. The results show that with appropriate parametric values, the DVA has great impact on the onset speed of galloping and can significantly alleviate the oscillation amplitude of the prism.