Relaxation base seismic isolator

Abstract

This paper deals with the use, for seismic applications, of a Maxwell element in parallel with a low damping isolator. The study of the properties of the frequency response function shows that this isolator is capable to reduce the base displacement of isolated structures with no considerable amplification of the non-isolated modes. This is, also, confirmed by the floor response spectra under earthquake excitations. Hence, the previously mentioned isolator does not present the drawbacks met when base displacement is reduced by increasing damping. Moreover, it seems that its performance is comparable with that of more elaborated and expensive techniques combining passive and semi-active devices.We notice that the two equations are coupled through the damping forces and the terms corresponding to the Maxwell element. Making the same assumption as Kelly [12] that the influence of the second mode on the first may be neglected, the equation of the first mode reads Figure 3. Frequency response function of the two-DOF system. a) Amplification coefficients of the response of the relaxation isolator with respect to that of the enhanced damping isolator in the vicinity of the two eigenfrequencies. b) Amplitude of the acceleration FRF at the base.

A new approach to inertial damper design to control base displacement in isolated buildings

“…Next, we review several proposals to solve this first or more important LBD problem, within passive control. To reduce the isolator displacement, there are tuned mass dampers (TMDs) (Palazzo et al, 1997; Taniguchi et al, 2008; Tsai, 1995), hysteretic isolators (Jangid, 2007), and application of absolute transmissibility from mechanical vibrations (Morales, 2003); also imported from mechanical engineering is the Zener isolator (Vu et al, 2016). This work is concerned with the linear TMD isolation technique; thus, a detailed review on this will be presented in a separate and next section.…”