International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 11 | Nov 2018 www.irjet.net p-ISSN: 2395-0072 © 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1324 Seismic Analysis of Multi-Storey Building with and without Floating Columns Mohammed Irfan 1 , C S Shashi Kumar 2 , M Keshava Murthy 3 1 Post graduate student, Dept. of civil engineering, UVCE, Bengaluru, India 2 Assistant professor, Vivekananda institute of technology, Bengaluru, India 3 Associate professor, Faculty of civil engineering, UVCE, Bengaluru, India ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - In the present study 3 different floor height buildings have been considered, the building to be analyzed as a whole by Time History Analysis for structure consisting floating columns in different positions in plan, building of G+3, G+10 and G+15 height is consider in earthquake prone zones. Comparison of results of Base Shear, Storey displacement and Acceleration of structure has done. FEM codes are developed for Structure with and without floating column to study the responses of the structure under different earthquake excitation having different frequency content keeping the PGA and time duration factor constant. The time history of floor displacement, Base shear and Acceleration are computed for Structure with and without floating columns. Key Words: Floating column, earthquake behavior, Time History Analysis,, Base shear, Storey displacement, Acceleration, ETABS 1. INTRODUCTION Many urban multistorey buildings in India today have open first storey as an unavoidable feature. This is primarily being adopted to accommodate parking or reception lobbies in the first storey. Whereas the total seismic base shear as experienced by a building during an earthquake is dependent on its natural period, the seismic force distribution is dependent on the distribution of stiffness and mass along the height. The behaviour of a building during earthquakes depends critically on its overall shape, size and geometry, in addition to how the earthquake forces are carried to the ground. The earthquake forces developed at different floor levels in a building need to be brought down along the height to the ground by the shortest path; any deviation or discontinuity in this load transfer path results in poor performance of the building. Buildings with vertical setbacks cause a sudden jump in earthquake forces at the level of discontinuity. Buildings that have fewer columns or walls in a particular storey or with unusually tall storey tend to damage or collapse which is initiated in that storey. Buildings with columns that hang or float on beams at an intermediate storey and do not go all the way to the foundation, have discontinuities in the load transfer path. A column is supposed to be a vertical member starting from foundation level and transferring the load to the ground. The term floating column is also a vertical element which at its lower level (termination Level) rests on a beam which is a horizontal member. The beams in turn transfer the load to other columns below it. Such columns where the load was considered as point load. Theoretically such structures can be analysed and designed. In practice, the true columns below the termination level are not constructed with care and more liable to failure. For Floating columns, the Transfer Girder and columns supporting Transfer Girder needs special attention. If load factor needs to be augmented (for Transfer Girder and its columns) to have additional safety of structure, shall be adopted. In the given system, floating columns need not be treated to carry any Earth Quake forces. Therefore entire Earthquake of the system is shared by the columns/shear walls without considering any contribution from Floating columns. However in design and details of Floating columns, minimum 25% Earth Quake must be catered in addition to full gravity forces. This way the overall system as some breathing safety during Earth Quake. However, Floating columns are competent enough to carry gravity loading but Transfer Girder must be of adequate dimensions (Stiffness) with very minimum deflection. Though floating columns have to be discouraged, there are many projects in which they are adopted, especially above the ground floor, where transfer girders are employed, so that more open space is available in the Ground Floor. The transfer girders have to be designed and detailed properly, especially in Earth Quake zones. If there are no lateral loads, the design and detailing is not difficult. 2. OBJECTIVES OF PRESENT WORK 1. To study the behavior of multistorey buildings with and without floating columns of various floor heights having same dimensions of beams and with columns. 2. To study the behaviour of structure located at earthquake prone zones with floating columns in different positions in plan area.