Experimental study on passive negative stiffness damper for cable vibration mitigation

Stay cables are vulnerable to excessive vibration because of their inherently low damping properties. Described in this paper is an experimental investigation of the vibration control performance due to passive negative stiffness dampers (NSDs) installed on a scaled stay cable model. The passive NSD used in the experiment was composed of a viscous damper and a magnetic negative stiffness spring with an adjustable stiffness coefficient installed close to one cable end in the transverse direction. In general, the passive NSD performed much more effectively than conventional viscous dampers in mitigating the vibration of the stay cable. As the negative stiffness strength increased, the cable responses under various dynamic loadings became smaller, thus indicating that high damping had been added to the stay cable. A damping ratio higher than 10% was obtained in the cable vibration tests. The flexural rigidity of the stay cable is a parameter often overlooked. However, after the installation of a passive NSD, this was found to be of importance. The actual influence of flexural rigidity depends on the negative stiffness coefficient, the damper location, and the boundary condition of the stay cable. Numerical simulation results taking account of the flexural rigidity and boundary conditions agreed well with the experimental results.