Negative stiffness device for seismic response control of multistory buildings

Weakening and damping of structures has proven to be an effective method for mitigating the structure's response. This approach has drawn further attention after the invention of negative stiffness device (NSD), developed by the authors. Preliminary analytical and experimental studies reported on the NSD have revealed that by adding the NSD to a single story structure the base shear demands and peak acceleration of the main structure are reduced significantly and the inter-story deformations are contained by adding a passive damper. In this paper an analytical study is carried on an inelastic multistoried shear building to demonstrate the effectiveness of placing NSDs and dampers at multiple locations along the height of the building. It has been shown that by placing a NSD in a particular story the superstructure above that story can be isolated. It has also been shown through simulation studies that the NSD will limit the amount of energy transmitted to the superstructure from the ground excitation. Essentially, NSD acts as a vibration isolator. Large base deformations is one major limitation in base-isolating the structural systems but using NSDs this can be overcome as the isolation is achieved over the height of the building and not confined to the base. It has been shown through the simulation studies that by placing NSDs in all the lower story's the acceleration of the superstructure and base shear can be reduced significantly without affecting the drifts. Simulation results of a nine-storied 1:3 scale inelastic shear building subjected to periodic ground motion and Kobe fault normal ground motion demonstrate the response of the multi-storied frame can be attenuated by incorporating NSDs.