Use of seismi̇c isolation for retrofit of exi̇sting reinforced concrete structures

In this study, a performance analysis was performed on a building which is assumed to be existed and was designed by using 1975 earthquake code. Two different retrofitting methods were proposed for the existing structure that has a performance level of collapse. In the first method, it proposed to increase the dimensions of the existing structural elements and to add new structural elements. In the second method, the use of seismic isolator was recommended to isolate the structure from the ground vibrations. In this method it was proposed to enlarge the dimensions of the basement floor columns of the structure first, then suspend these columns and install the seismic isolators to the cut parts. The structures which retrofit methods were applied were subjected to performance analysis again and the performance levels after retrofit were determined. As a result of both retrofit method, life safety performance level was observed in the structure. In all performance analyses, nonlinear time history analysis technique is used. The comparison of the two retrofitting methods was done by comparing the periods, floor shear forces, floor displacements and story drift ratios of the existing building and the two retrofit alternatives. Finally, the costs of the two retrofitting methods were compared.