International Journal of Engineering Research

S. D. Darshale ¹, N. L. Shelke ¹

Affiliations
1 Civil Engineering Department, Dr. D. Y. Patil School of Engineering and Technology, Charholi (Bk), Pune, IN

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.

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