Seismic pounding effect on two adjacent RCframed multistorey buildings using time history analysis.

Resumo

Seismic pounding is defined as the collision of structures during earthquakes when these structures have different dynamic characteristics. It is an instance of rapid strong pulsation like hammering and repeated heavy blows. This pounding of closely spacedbuildings can be seen largely in some densely populated urban areas. Some modern codes have included seismic separation gap requirement clauses for adjacent structures but since large parts of 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 earthquakes on a single building. Thus, the action of pounding of buildings needs to be mitigated to avoid loss of life and property during earthquakes. The problem of pounding is particularly common in many cities in India, located in seismically active zones, where due to various socio-economic factors and land usage requirements, buildings are often constructed crowded together. This paper is focused on the study of the seismic pounding between two RC buildings with different dynamic characteristics. A systematic study of response of seismic pounding between adjacent buildings and seismic hazard mitigation practices like effect of different separation distances and effect of providing dampers are investigated, using the ETABS software. A 12-storey and a 16-storey building have been considered for the study of pounding. Time history analysis is carried out for seven real earthquake ground motions on the models with varying separation gaps. The results were obtained in the form of pounding force and point displacements. It is revealed that the pounding effect varies inverselywith the separation distance. With increasing separation distance pounding effect is reduced greatly and so the damage to the neighbouring buildings is also minimized. Also, the pounding forces are seen to be decreasing considerably between the adjacent buildings due to the provision of dampers at suitable locations, as compared to the case of adjacent buildings without dampers. The study even confirms that the pounding effect can be mitigated considerably by installing dampers between adjacent structures.Dampers modelled in this study prove to be effective in reducing the displacement and driftin the range of15%-20%