Seismic Control of Soft Storey Buildings Using LRB Isolation System

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Sustainable development not only deals with the protection of environment but also with the development that can be sustained for generations. Large part of the world is subjected to earthquake forces, which demands that structural engineers have to design the buildings so that it can withstand the consequence of these earthquakes. In order to mitigate this problem, seismic base isolation technique is used in recent years. In seismic base isolation, laminated rubber bearing (LRB) is the most extensively used technology, because of its fruitfulness and reliability. The principal purpose of seismic isolation is to lessen the seismic demand on structure. Isolation works on the principle of increasing structural time period. Hence decreasing the vulnerability of earthquake demand on the structure. In urban environment, for the purpose to provide parking facility at the ground storey of building, the concept soft storey has taken its place. However, the buildings with soft storey are most vulnerable to earthquake. In Bhuj earthquake (2001), most of the buildings damaged were of soft storey type. This investigation is to find out the efficacy of laminated rubber bearing isolation system in managing the reciprocating action of the soft storey frame model for the installation of isolation system at the top and at the bottom of soft storey column when subjected to El Centro, 1940 ground motion by using state-space method and a comparison is made between structures with and without infill wall. The response behavior in terms of absolute acceleration, inter storey drift, and storey shear have been investigated, for example, building models. With the use of isolation system, storey shear for all storey level is reduced. When LRB is placed at bottom of soft storey column base shear is reduced by 31.91% and absolute top floor acceleration is reduced by 42.23% that of soft storey building with fixed base.KeywordsEarthquake-resistant buildingLaminated rubber bearingSoft storey buildingBase isolation