Dynamic behavior of nonlinear rolling isolation system

Abstract

The linear isolator has fixed vibration frequency. When structures with these linear isolators are located near a fault, it may cause resonance and large displacement response. Hence, nonlinear isolation may avoid this situation. In this study, an eccentric nonlinear rolling isolator with a parameter, which is the eccentricity of the pin connection of the mass block (facility) to the circular isolator, is investigated. If the eccentricity is not equal to zero, the dynamic response is nonlinear rolling behavior. The equation of motion of the isolation system is derived. The frequency of the isolator increases with the eccentricity under the same initial angle. The influence of the eccentricity to the effect of isolation is scrutinized. Finally, the feasibility of the proposed isolation device is verified numerically. If the proposed isolator is designed properly, it is effective for far-field earthquake (El Centro earthquake). Even though the linearized frequency of the proposed isolator falls into the dominant frequency range of near-fault earthquake (Chi-Chi earthquake), resonance can be avoided due to nonlinearity.

Rolling devices for seismic isolation of lightweight structures and equipment. Design and realization of a prototype

“…Studies have been conducted on roller devices by Butterworth; he proposed a rolling isolation system consisting of rollers with nonconcentric spherical upper and lower surfaces, in which the isolation period becomes a nonlinear function of the isolator displacement. Compared with a conventional isolator with a constant period, a nonlinear rolling system is able to reduce the peak acceleration with smaller reduction in peak displacement for high‐intensity earthquakes …”

Parameters Influencing the Response of a Base-Isolated Building

“…In this context, it has been proved that mounting structures on a base isolation is an important design strategy for protecting buildings from an earthquake's strong motions [7].…”

Tri-directional shaking table tests of vibration sensitive equipment with static dynamics interchangeable-ball pendulum system

“…Recently, the isolation technology has been acknowledged as an effective method to promote the earthquake resistibility of the structures on the basis of theoretical and experimental results and earthquake events. Several theoretical studies have been made on the applications of the base isolation technology to critical equipment in seismic mitigation (Alhan and Gavin, 2005;Chung et al, 2008). However, little attention has been given to the experimental study of the effi ciency of base isolation on the protection of vibration sensitive equipment in the events of earthquakes, especially for experimental investigations under tri-directional seismic loadings (Tsai et al, 2005a(Tsai et al, , 2007(Tsai et al, , 2008Fan et al, 2008).…”