Comparative study on seismic analysis of a multi-storied building with and without floating column

In highly crowded urban areas, provision for the accommodation of parking locations, reception lobbies, terrace gardens, etc are of great concern. Building with a floating column can be a viable option and can be advantageous, but it is necessary to investigate its cost-effectiveness and structural performance during strong ground motion resulting from earthquake excitation. The overall shape, size, and geometry of a building influence its characteristics and behavior under seismic loading. That is why the performance of floating column buildings with respect to normal buildings in seismic-prone areas needs to be evaluated. In this study, both the static and dynamic analysis methods are engaged to observe the performance of the buildings having floating columns for seismic loading in accordance with the provision stated in BNBC 2020. Four different cases where buildings with varying locations of floating columns are analyzed along with the normal building that has no floating column. From the analytical results, it is observed that story displacement, story drift, and base shear are increasing quite rapidly in those buildings that have floating columns (Case II, III, and IV) compared to a normal building. Floating column buildings undergo relatively more horizontal displacements due to an increase in the fundamental time period which can cause damages to structural and non-structural members if the lateral displacement exceeds the code stipulated maximum limit. Seismic base shear and overturning moment are also increasing for the cases of buildings with floating columns due to discontinuity in load distribution path. Also, torsional irregularity has been developed but modal mass participation ratio has been decreased when floating columns are introduced asymmetrically. It can be said that the provision of floating columns in highrise buildings is beneficial in providing an uninterrupted open floor space but at the same time they are risky and vulnerable in seismic-prone areas.