A Novel Base Isolation System for Asymmetric Buildings in Seismic Active Zones: Damping Supplied by Tuned Liquid Column-Gas Dampers

Abstract

The vulnerability of civil engineering structures with fundamental frequency, say roughly above 1 Hz, (or buildings with less than 10 stories), when exposed to the strong motion phase of an earthquake is considerably reduced by means of base isolation. The low pass filter for isolating horizontal vibrations is redesigned where the classical elastomeric bearings are substituted by a number of prestressed helical steel springs with pivoted columns along vertical axes carrying part of the dead weight and guiding the horizontal motion. The base isolated building in its fundamental modes is considered to be rigid. Low cost Tuned Liquid Column Gas Dampers, in optimal arrangement in the plan of the basement of the building, supply the effective damping of the remaining horizontal vibrations. The action of the passive damping device is commonly considered to be sufficient. Since the gas spring effect counter acts changes in fluid mass, the absorber can be used as a water reservoir. However, early peaks in the response may require active control for their proper reduction. Consequently, such a hybrid absorber is discussed with gas injection from a standby high-pressure vessel, making it independent from any public energy transmission line.