Seismic Retrofitting of Floating Column Building with Fluid Viscous Dampers and Structural Bracings by using Fast Non-linear Time History Analysis

Abstract

In some of the building structures, even in the newly constructed one, floating columns are used to achieve an aesthetic view or to satisfy the space requirement criteria of building areas like reception lobbies, parking spaces, conference rooms in malls etc. With the use of proper design considerations, buildings built with floating columns, which otherwise are not advised by the codes, can withstand vertical loads, i.e., gravity loads and live loads, and to certain extent may withstand the small-scale earthquake loads. However, due to vertical irregularity, that is discontinuity in load transfer from floating columns, it is more vulnerable to the earthquake loads, sometimes even to small-scale earthquakes and can lead to increased structural responses and corresponding forces in the structure. For this purpose, the response of the building can be decreased by using a seismic retrofitting technique to increase the overall performance of the building. G+9 residential floating column building is analyzed in the present study by using dynamic analysis. Arrangements are done in such a manner that use of only dampers, only bracings, a combination of both dampers and bracings as in Type 1, Type 2, Type 3, and Type 4 arrangements respectively, are considered. Location of dampers and bracings are fixed at successive and alternative floors corresponding to the height of the structure to overcome the best result in seismic retrofitting of the structure. Such arrangements are analyzed and studied by using fast non-linear time history analysis with an El Centro earthquake in ETABS v 2018. With the use of the performance controllability index, optimization of location and number of dampers can be found out using root mean square values of inter storied drifts. It can be seen that the Type 4 arrangement is quite effective arrangement to increase the overall performance of the structure with economic considerations.