EFFECT OF SUPPLEMENTAL DAMPING ON LRB AND FPS SEISMIC ISOLATORS UNDER NEAR-FAULT GROUND MOTIONS

Abstract

Numerical simulations are performed to assess the effects of near-fault ground motions on baseisolated buildings that consist of either lead-rubber (LRB) or friction-pendulum system (FPS) bearings in addition to supplemented viscous dampers. While LRB and FPS isolation systems have been applied for a number of years, the addition of supplemental damping devices is being currently considered for strong ground motions to reduce the isolator displacements. However, the main problem in this case is that the addition of damping may increase both internal deformation and absolute accelerations of the superstructure and thus may defeat many of the gains for which base isolation is intended. In the present paper, a detailed and systematic investigation on the performance of LRB and FPS isolation systems, provided with supplemental viscous damping under the effect of near-fault ground motions, will be carried out by using commercial finite element software. In the present analysis, a residential building with 20 floors is to be analyzed with columns, columns with LRB and FPS isolation systems. The building comes under zone 2 & zone 5. Moments, Storey Shear, Drift and Torsion will be compared for all the cases. Earthquake load is becoming a great concern in our country as because not a single zone can be designated as earthquake resistant zone. One of the most important aspects is to construct a building structure, which can resist the seismic force efficiently. Study is made on the structural arrangement to find out the most optimized solution to produce an efficient safe earthquake resistant building. A commercial package ETABS has been utilized for analyzing high-rise building of 20 stories in different zones with respect to three types of soils. The result has been compared using tables & graph to find out the most optimized solution. Concluding remark will be made on the basis of this analysis & comparison tables.