Seismic response control of a building by negative stiffness devices

Abstract

Two analytical studies for the seismic response of a multi-degree-of-freedom shear model controlled by pseudo-negative stiffness (PNS) device and true negative stiffness (TNS) device are presented. The first study intends to optimise the parameters of the control devices for maximum response reduction. The optimal number and location of devices required to achieve the optimal reduction of seismic responses are investigated. In the second study, the performance of the negative stiffness devices, TNS and PNS, are compared with each other and also with a conventional viscous fluid damper (VFD) based on their seismic response reduction capability; different control strategies are adopted for the comparison. The building model considered is a shear type, lumped mass one with a lateral degree-of-freedom at each floor. The governing equations of motion are solved using Newmark’s beta method for a linear variation at a small time interval for six earthquake ground motions. The results indicate that the PNS and TNS devices performed better than the conventional VFD. However, the negative stiffness behaviour of the devices tends to increase certain responses as compared to the conventional damper. Furthermore, the addition of a conventional damper was found to improve the negative stiffness device’s performance as the possible increase in deformation due to such devices is controlled.