Seismic Vulnerability Analysis of Multistorey Base Isolated RC Building

Abstract: By lengthening the period of vibration of the structure, seismic isolation allows for a reduction in earthquake forces. Isolated structures are typically retained at a period of 2 seconds. As a result, isolation provides significant benefits in buildings where the basic duration of vibration without base isolation is less than 1.0 sec. This work provides an analytical study of baseisolation for buildings with natural periods of 1.0 to 3.0 seconds. Various options are investigated in order to improve the viability of base isolation for such structures. Strategies proposed in this study are (i) increasing superstructure stiffness, (ii) increasing superstructure damping and (iii) increasing flexibility of isolation system. It is observed that the effectiveness of base isolation for these buildings may be increased by incorporating such provisions. The purpose of this research is to see how performance-based building design and following the above tactics can improve the effectiveness of base isolation in structures with matching time histories and response spectrum seismic analyses. In this analysis, G+7 storey structures are taken into account. Seismic isolation enables the reduction in seismic forces by increasing the time period of the structure. The usual period of isolated structures is generally kept as 2 sec. Therefore; the significant benefits obtained from isolation are in structures for which the fundamental period of vibration without base isolation is short, less or upto 1.0 sec.