International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 11 Issue: 05 | May 2024
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p-ISSN: 2395-0072
SEISMIC PERFORMANCE OF BASE ISOLATED 3D RC STRUCTURES CONSIDERING EXISTING EARTHQUAKE DATA Nishma TH1, Dr.Chethan K2 1 P.G Student, Department of Civil Engineering, U.V.C.E, Bangalore University, Bengaluru
2 Associate Professor, Department of Civil Engineering, U.V.C.E, Bangalore University, Bengaluru
---------------------------------------------------------------------***--------------------------------------------------------------------past 20 years. These are extremely rigid bearings although Abstract - For reinforced concrete (RC) buildings to
they are highly adaptable, they can support the building's vertical weight in the vertical direction horizontally, allowing the structure to shift laterally in the event of extreme ground motion. their creation represented a growth in the application of elastomeric bridge bearings and bearings for the building's isolation from vibration. The concept of base isolation is now widely accepted in earthquake-prone regions of the world for protecting important structures from strong ground motion; there are currently many examples in the United States and Japan. Other systems that are modifications of the sliding approach have been developed in recent years.
maintain their structural integrity and the safety of its occupants during earthquakes, seismic performance assessment is essential. The first step in the research is to create ETABS models that faithfully capture the dynamic behaviour of reinforced concrete buildings. Subsequently, the LRB and HDRB isolators are reviewed, chosen, and designed. Time history loads are applied to determine the models' reaction. Assessing the effectiveness of isolators in reducing earthquake-induced damages by contrasting the exceedance probabilities of fixed and base isolated structures. The study's findings offer crucial data for assessing the structure's anticipated seismic performance and creating focused mitigation plans. Various preceding earthquakes are considered and compared to obtain the better performance. Total seven earthquakes with reference to IS 1893:2016 (part 1) are taken. With infill that is with equivalent diagonal strut and without infill having two types of storey- low rise and medium rise with basic beam-column-slab structures are used in this thesis
1.2 Objectives Aims to perform Finite Element Analysis (FEA) for fixed base and base isolation for 3D RC building for Seismic loads. Design and apply base isolators at the supports 3D RC Buildings are done. Carry out Finite elemental analysis which involves modal analysis and Time history analysis and compare the fixed base results with base isolated models for different storey height.
Key Words: Base isolation, Lead rubber bearing, High damping rubber bearing, equivalent diagonal strut.
2. DEFINITION OF MODELS
1.INTRODUCTION
RC framed structure with and without infill is considered, two types of building in terms of height is being considered, low rise (5 Floors) and medium rise (13 Floors). All the models have 5 bays of 8 m width in both perpendicular directions in the horizontal plane. Time history analysis is carried out in ETABS software. The structural material is assumed to be isotropic and homogeneous.
In earthquake-prone regions, the importance of earthquakeresistant buildings cannot be overstated. They are a critical component of disaster preparedness and risk reduction, helping to protect lives, property, and the overall well-being of communities. Building structures that can withstand seismic forces is a proactive and responsible approach to managing the risks associated with earthquakes. The ground that underpins every building shift during earthquakes. As a result, the building's base moves along with it. However, the building will make an effort to resist this motion because of its inertia. The building gets distorted as a result, and this distortion increases with the building's height.
Various loads are applied to the structural models. Part I of the Indian Standard Code of Practice for the Structural Safety of Buildings, IS 875-1987, specifies the loads that were taken into account for the study. The loads taken into account in this work are i. Dead Load designated as “DL”
1.1 Concept of Base Isolation
ii. Live Load designated as “LL”
Base isolation is a seismic-resistant design strategy that seeks to break the direct mechanical link between a building's superstructure and its foundation. With the arrival of multilayer elastomeric bearings, which are created by vulcanizing rubber sheets to thin steel reinforcing plates, the idea of seismic isolation has become a reality throughout the
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iii. Earthquake Load designated as “EQX”, EQY” & “TH”
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