A comparative study on the performances of linear, cubic, and quasi-zero-stiffness absorbers in mitigating galloping oscillations

Abstract Galloping-induced vibrations pose a significant threat to the stability and durability of slender bluff-body structures exposed to wind flows. Inspired by the successful application of quasi-zero stiffness (QZS) isolator in base excitation scenarios, this study aims to investigate the effectiveness of this novel passive nonlinear method for suppressing galloping-induced vibrations. First, the mathematical model of the coupled system is established and parametric studies are performed to determine the optimal system parameter. Next, to evaluate its overall performance compared to traditional passive control methods, specifically linear and cubic absorbers, a comprehensive comparative study is conducted on these three methods. The results show that up to the wind speed of 20 m/s, which corresponds to the No. 8 Beaufort wind scale (fresh gale), linear absorber outperforms both nonlinear absorbers, with a cut-in wind speed improvement of 188.9%, compared to 26.8% for both nonlinear absorbers. Besides, QZS absorber outperforms pure cubic absorber in terms of the jump wind speed. This suggests that the effectiveness of QZS absorber in base excitation scenarios is not applied to flow-induced excitation scenarios. Furthermore, the nonlinear dynamic behaviour of the QZS absorber is explored based on the numerical continuation technique via MATCONT, and bifurcations are observed. Finally, the system is nondimensionalised, and an approximate-analytical solution is derived using the harmonic balance method. This analytical approach further illustrates the complex bifurcation characteristics of the system.