Seismic Pounding Response of Tall Buildings Installed with Fluid Viscous Dampers

Seismic pounding is defined as the collision of structures of different dynamic characteristics during earthquakes. It is an instance of rapid strong pulsation like hammering and repeated heavy blows. Pounding of closely spaced buildings can be largely seen in densely populated urban areas. IS 1893 (2016) (in IS 1893 (Part 1), Criteria for earthquake resistant design of structures—general provisions and buildings, 2016) has included seismic separation gap requirement clauses for adjacent structures. However, since large parts of the metropolitan cities in seismically active regions of India were built before such requirements were introduced, the seismic separation gap requirements have not been fulfilled. Pounding can be catastrophic and even more dangerous than the effect of earthquake on a single building. Thus, the act of seismic pounding of buildings needs to be mitigated to avoid loss of life and property. The problem of pounding is common in many cities in India, where due to various socio-economic factors and land usage requirements, buildings are often constructed very close to each other. This paper is focused on the study of the seismic pounding between two reinforced concrete (RC) buildings with different dynamic characteristics. A systematic study of response of seismic pounding between two adjacent buildings and seismic hazard mitigation practices like effect of different separation distances, and effect of providing dampers, are investigated using ETABS software (in CSI Analysis Reference Manual, Computers & Structures, Inc., California, USA, 2017). A 12-storey and a 16-storey building have been considered for the study. Time history analysis is carried out for seven real earthquake ground motions on the models with varying separation gaps. The parameters considered are pounding force and contact point displacements. It is revealed that with increasing separation distance pounding effect is reduced significantly. Further, the pounding forces between the adjacent buildings are seen to be decreasing considerably due to the provision of dampers at suitable locations; as compared to the case of adjacent buildings without dampers. The study confirms that the pounding effect can be mitigated considerably by installing dampers between adjacent structures. Fluid viscous dampers modeled in this study prove to be effective in reducing the displacement and acceleration response in the range of 20–30%.