Effects of LRB Isolators and Viscous Dampers on Seismic Isolated Irregular Reinforced Concrete Buildings

Abstract

The aim of this paper is to present the effects of lead rubber bearings (LRB) or viscous dampers (VD) in irregular in plan reinforced concrete buildings. The buildings (a three-story building, an eight-story building, and a twenty-story building) had been studied under earthquake recorded accelerograms, three of them are real and the other four are artificial, by nonlinear dynamic time-history analyses. In this paper the optimal design of LRB bearings and viscous dampers is described, focusing the design on minimizing certain parameters: (i) the maximum displacement (top of the structures), (ii) the torsion of the buildings, (iii) the base shear loads and, (iv) the maximum horizontal interstory drift. The comparative results show the effectiveness of the VD in terms of minimizing the torsion effects for all the buildings, and mostly in the low rise one. However, the use of LRB provides a significant reduction for all the buildings in terms of minimizing the rotation, the maximum acceleration, the max-story drift, the maximum displacement and the base shear loads.