Seismic responses and energy dissipation of pure-friction and resilient‐friction base-isolated structures: A parametric study

Abstract

A comprehensive parametric study is carried out on pure-friction base-isolated (P-FBI) and resilient‐friction base-isolated (R-FBI) structures in this paper. For this purpose, an 8-story building subjected to a band-limited white noise acceleration modeled based on a stationary process is considered. At first, the time histories of seismic response and superstructure energy for P-FBI and R-FBI structures are compared with those given for a fixed-base (F-B) structure. A vast range of values for the friction coefficient of the sliding surface, mass ratio of the base story, target period, and damping ratio of the restoring device are also considered for the parametric study. Then, the effect of changing these parameters on the maximum response of stories and superstructure energy is investigated. Considering a low friction coefficient, it is concluded that the restoring device of the R-FBI structure is able to significantly reduce displacement of the base story during earthquake excitations. It is also capable to return the base story to its original location at the end of an earthquake. Simulation results also show that the restoring device increases the maximum seismic input energy entered into the superstructure but reduces the maximum seismic damage energy of the superstructure. Results demonstrate that the amount of friction coefficient has the greatest effect on seismic responses of the studied structure. Base displacement is reduced with increasing friction coefficient, but top floor acceleration and superstructure drift are significantly increased, which results in an increment in maximum input and damage energies. Overall results indicate that an increment in damping ratio of the restoring device results in a reduction in maximum base displacement and top floor acceleration, and an increment in maximum top floor displacement and drift, while it has no effect on the residual base displacement. Moreover, base displacement and top floor drift are increased by increasing the period of the restoring device, while other seismic responses are reduced.