Seismic Response of Reinforced Frame Structure with Soft Stories At Different Floors

Abstract

In general practice soft stories means, RC frame building structures without infill panels comprises of walls of brick, blocks and many more types of partitions. In this lateral stiffness is about less than 70% of that in story above immediately or less than 80% of average lateral stiffness of these stories above them. The infill masonry partitions walls are rarely considered as structural system components in an analysis of reinforced concrete structure. Although it is considered as a non-behaving components parts of building unit. Even when as partition they also show structure response and although panels of partitions considered and included in analysis.
Recently, it becomes important to carry out seismic behavior of frame structure with and without infill walls. Parametric analysis of large variety of multistory building structure show that hysteric dissipation of energy in the infill are uniform in all the way in all story , dissipation and drift and structural damage are reduced dramatically , without any increase in demand of seismic force. Absence of any infill bottom story as it shows less strong and more flexible large deflection of that building tends to concentrate on that floor with effect of stress at second floor and hence collapse is unavoidable. In modern construction of multistoried building construction in India typical feature to open the first story such type of feature is unavoidable in seismically active areas. This is been verified in very
numerous ways of strong earthquake excitation.