This paper systematically investigates the dynamic behavior of stay cables with passive negative stiffness dampers (NSD) installed close to the cable end. A passive NSD is modeled as a combination of a negative stiffness spring and a viscous damper. Through both analytical and numerical approaches, parametric analysis of negative stiffness and viscous damping are conducted to systematically evaluate the vibration control performance of passive NSD on stay cables. Since negative stiffness is an unstable element, the boundary of passive negative stiffness for stay cables to maintain stability is also derived. Results reveal that the asymptotic approach is only applicable to passive dampers with positive or moderate negative stiffness, and loses its accuracy when a passive NSD possesses significant negative stiffness. It has been found that the performance of passive NSD can be much better than those of conventional viscous dampers. The superior control performance of passive NSD in cable vibration mitigation is validated through numerical simulations of a full-scale stay cable.

No abstract

No abstract

No abstract

Among active, semiactive, and passive vibration isolation methods, active control can provide the best isolation performances. However, high-energy consumption hinders its wide applications in civil engineering field. This paper proposes a novel vibration isolation technique based on a passive negative stiffness spring (NSS) and a semiactive device (SAD), aiming to achieve an active isolation performance by using a low-power semiactive technique. Due to its nature of negative potential energy, an NSS enables the semiactive isolation system to provide negative transient power flow that injects power into the structure and avoids the clipping phenomenon of semiactive control forces. Consequently, the combined NSS and SAD isolation system can perfectly generate the theoretical control forces calculated by an active control algorithm and achieve a considerably improved semiactive isolation performance. The prospects and performance advantages of the proposed NSS and SAD isolation system are validated through a series of numerical simulations of single-degree-of-freedom and multi-degree-of-freedom structures excited by various types of ground motions and a benchmark building model excited by seismic ground motions.