International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 11 | Nov 2025
p-ISSN: 2395-0072
www.irjet.net
Comparative Analysis of Isolated Lead Rubber Bearing and Fixed Base Structures in Compliance with Indian Standard Mr. Kaushik Waghmare1, Dr. A. P. Patil2 1Post Graduate Student, Dept. of Civil Engineering, Datta Meghe College of Engineering, Airoli, Navi-Mumbai 400708, Maharashtra, India 2 Assistant Professor, Dept. of Civil Engineering, Datta Meghe College of Engineering, Airoli, Navi-Mumbai 400708, Maharashtra, India ---------------------------------------------------------------------***--------------------------------------------------------------------1.1 General Description of Base Isolation Abstract -Base isolation has become an accepted and effective approach to proactively addressing the issues Systems associated with earthquake loads. In particular, base isolation reduces floor accelerations and inter-storey drifts. This increases not only the safety of the structural and nonstructural components within the structure, but also allows the building to remain functional after a major seismic event. The performance of base isolation systems is determined predominantly by the linear and bilinear characteristics of the isolators. This paper compares the seismic performance of a base-isolated structure to a fixed-base building. A G+12 storey building model was developed and analysed using ETABS 19 software, and employed Lead Rubber Bearings (LRB) to create a base-isolated structure. The analysis includes a comparison of various response parameters such as displacement, interstorey drift, storey shear, and storey acceleration. The LRB's isolator properties were modelled as linear, and a response spectrum analysis was conducted in accordance with IS 1893 (Part 6): 2022. The conclusion provides a summary of the findings from the study and provides suggestions for future research related to the enhanced seismic performance of base isolation systems and the continued refinement to seismic isolation design technology.
In the last four decades, a significant amount of research work, both analytical and experimental, has been done to assess the effectiveness of base isolation systems to reduce dynamic seismic response. The deployment of base isolation makes the building more flexible, hence a large natural time period. This, in turn, reduces the spectral acceleration and hence lateral seismic force. However, to enhance flexibility, the lateral deflection is increased, which has to be kept within a permissible limit. Thus, there are certain requirements that base isolation devices should fulfil.
1.2 Basic Principle of Base Isolation:
Key Words: Base Isolation, Lead Rubber Bearings (LRB), Response Spectrum Analysis, IS 1893 (Part 6): 2022
In the case of seismic loading, the most popular way of quantifying the demand is by using the response spectrum. Response spectrum is a plot of spectral parameters (acceleration, velocity or displacement) versus the time period for some given level of damping. As such, the spectral parameters are seen to be some function (which we call the response spectrum) of the time period of the structure and the damping. The spectral parameters are used further to calculate the demand on the various components of the structure. Thus, it is concluded that the seismic demand on a structure is a function of its time period and damping.
1. INTRODUCTION
2. METHODOLOGY
In recent years, the rise of tall and slender high-rise buildings has made them increasingly vulnerable to lateral forces such as wind and earthquakes, requiring modern structural designs to focus on both strength and stability under these loads. Seismic design now emphasises understanding inelastic structural behaviour to ensure life safety and controlled energy dissipation during earthquakes. Among various seismic protection methods, base isolation has proven highly effective in minimising earthquake damage. Originating in the early 20th century and widely adopted since the 1980s in countries like Japan, the USA, and New Zealand, base isolation has also been implemented in India, first after the 1993 Killari earthquake and notably in the Bhuj Civil Hospital following the 2001 Bhuj earthquake.
This research systematically evaluates the seismic performance of base-isolated structures using Lead Rubber Bearings (LRBs) and conventional fixed-base structures. Following a site investigation and literature review on base isolation and seismic design codes, identical structural models are developed for both systems to ensure a fair comparison. Using ETABS 19, the models are designed and analyzed through response spectrum analysis in accordance with relevant seismic codes. Key parameters such as fundamental time period, base shear, storey displacement, storey drift, and diaphragm acceleration are compared to assess differences in seismic response, deformation control, and overall structural performance.
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In conclusion, percentage changes in key parameters are calculated to compare the performance of LRB base-isolated and fixed-base systems. The results highlight improvements
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