International Journal of Engineering Research ISSN:2319-6890)(online),2347-5013(print) Volume No.5 Issue: Special 2, pp: 683-689 27-28 Feb. 2016 NCASE@2016 doi : 10.17950/ijer/v5i3/036 Page ͸ͺ͵ Seismic Response Control of Vertically Irregular R.C.C. Structure using Base Isolation S. D. Darshale, N. L. Shelke Civil Engineering Department, Dr. D. Y. Patil School of Engineering and Technology, Charholi(Bk) Pune,India email: sachindarshale@gmail.com Abstract: In recent years considerable attention has been paid to research and development of structural vibration control devices with particular emphasis on mitigation of wind and seismic response of buildings. Many vibration-control measures like passive, active, semi-active and hybrid vibration control methods have been developed. Base isolation is a passive vibration control system. The isolator partially reflects and partially absorbs input seismic energy before it gets transmitted to the superstructure. Lead rubber bearing isolators are placed between the superstructure and foundation, which reduces the horizontal stiffness of the system. It thereby increases the time period of the structure and decreases the spectral acceleration of the structure. The superstructure acts like a rigid body, thus inter storey drift is reduced. This study is concerned with the effects of various vertical irregularities on the seismic response of a structure and controls this response using base isolation. The objective of the study is to carry out response spectrum analysis and time history analysis of fixed base and base isolated vertically irregular RCC structure according to IS 1893:2002 (Part-1). Three types of vertical irregularities namely mass irregularity, stiffness irregularity and vertical geometry irregularity were considered. From the modal analysis of G+14 regular RCC structure, first mode time period of fixed base building is found to be 1.762 sec. whereas the first mode time period of isolated building is found to be 4.343 sec. Base isolation reduces the lateral displacement, shear forces, bending moments, base shear, storey acceleration, interstorey drift as compared to the conventional fixed base structure. Which shows the effectiveness of base isolation and concluded that base isolation is very effective seismic response control device. Keywords: Vertical irregularities, Fixed base, Base isolation, Response spectrum analysis, Time history analysis, ETABS software. 1. Introduction 1.1. Seismic Response Control Conventional seismic design attempts to make buildings that do not collapse under strong earthquake shaking, but may sustain damage to non-structural elements and to some structural members in the building. Non-structural components may consist of furniture, equipment, partitions, curtain wall systems, piping, electrical equipment and many other items. There are mainly three main categories: architectural components, mechanical and electrical equipments, and building contents. This may render the building non-functional after the earthquake, which may be problematic in some structures, like hospitals, which need to remain functional during the earthquake. Non-structural components are sensitive to large floor accelerations, velocities, and displacements. When a building is subjected to an earthquake ground motion, the building induces motion, resulting in floor accelerations higher than the ground acceleration. Hence, it is present need and also a duty of civil engineers to innovate earthquake resisting design approach to reduce such type of structural damages. Special techniques are required to design buildings such that they remain practically undamaged even in a severe earthquake. There are two basic technologies used to protect buildings from damaging earthquake effects. These are base isolation devices and seismic dampers. Many vibration-control measures like passive, active, semi-active and hybrid vibration control methods have been developed. Base isolation is a passive vibration control system. The isolator partially reflects and partially absorbs input seismic energy before it gets transmitted to the superstructure. The idea behind base isolation is to detach (isolate) the building from the ground in such a way that earthquake motions are not transmitted up through the building, or at least greatly reduced. Seismic dampers are special devices introduced in the building to absorb the energy provided by the ground motion to the building. Figure 1 The concept of base isolation