Summary
This study investigates the concept of clearance-type nonlinear energy sinks (NESs) for the passive mitigation of a model of a five-story shear frame structure subjected to seismic excitation. This is achieved by introducing two local NESs with linear internal restoring springs and dampers, incorporating single-sided clearance stiffness. By increasing the clearance stiffness to a relatively high value, the limit of single-sided vibro-impact (SSVI) is achieved. The introduction of these non-smooth clearance-type NESs yields significant outcomes. Firstly, there is a substantial reduction in the portion of seismic input energy penetrating the structure compared to an unprotected one, while simultaneously maintaining low acceleration levels. Secondly, it facilitates rapid, robust, and irreversible targeted energy transfer (TET) from the linear primary structure to the local NESs, leading to passive energy localization in the attachments. Thirdly, the clearance nonlinearities induce intermodal targeted energy transfer (IMTET) from low to high-frequency structural modes, thereby enhancing energy dissipation performance right from the initial cycle of the structural response. Lastly, properly designed single-sided clearance-type NESs demonstrate robustness across a broad spectrum of seismic input energy levels and frequency content, even under severe ground excitations. The seismic loads are simulated using records from three historical earthquakes: the 1994 Northridge, 1995 Kobe, and 1940 El Centro.
