Impact of the Lead Rubber Base Isolators on Reinforced Concrete Building

Civil engineering infrastructures are prone to natural disasters like earthquakes, floods, and hurricanes. Dissipation energy plays the main role in design of structures under Earthquake loads and controls the behavior of buildings when it bears the lateral loads and transfers them to the foundation. To resist the vibrations in the structure, it is important to use a high technology like Base isolation which reduces base frequency of building vibration and reaching it to a lower value. In other words, seismic isolation has the main objective to protect structure during earthquake events. Base isolation is a flexible layer between foundation and superstructure thus decoupling the structure from damaging effect of ground motion. This edits the dynamic characteristics of the structural system. A comparative study is conducted of seismic performance on three types of thickness (100mm,200mm, 300mm) in which M1T1, M2T1, M3T1, M1T2, M2T2, M3T2, M1T3, M2T3, M3T3, M1T4, M2T4, and M3T4 has been analyzed of isolators namely Lead Rubber Base Isolators (LRBI). For this evaluation, an 8-story structure has been analyzed by using (ETABS) finite element program where Models have ordinary RC moment- resisting frames with square column cross- sections. Parameters like drift, displacement, story acceleration, frequency, and story velocity have been analyzed and it has been found that due to the presence of Lead Rubber Isolators the story drift, story accelerations, base shear, lateral shear forces, and velocity are greatly reduced and story displacement is increased in both X and Y directions compared for various thickness of lead rubber base isolation systems under near and far-field earthquakes. Most importantly it has been established that the transmission of the high energy seismic waves to the superstructure is greatly reduced by introducing base isolators in between the top of the footing and the bottom of the superstructure. The base isolator with thickness 100mm for the concrete grade M20, M30, M40 performed more efficiently than other thicknesses. In conclusion, the deformation and transmissibility ratio must be minimized to introduce as a solution for absorbing the vibrations where the engineer should consider this effect for adequate design.