A Parametric Study for Analysis of Space Frame with Isolated Footings Supported on Winkler's Spring Base With Reference To Idealized Fixed/Hinged Base

A G+3 storied reinforced concrete Space frame having 3 bays of 5m each in X direction and 3 bays of 4 m each in Y direction located in seismic zones IV and V has been analyzed with the fixed, hinged and flexible foundation. The building with the flexible foundation has been analyzed incorporating soil-structure interaction (SSI) effects. For flexible foundation frame is supported by isolated footing on Winkler’s spring bed. Winkler’s spring base is applied in software by assigning nodal springs having value equal to soil stiffness at the base of discretized plate. Soil-structure interaction (SSI) effects as per FEMA 356 are also done. The space frame is subjected to various combinations of gravity and earthquake loads. The space frame is analyzed keeping its base fixed and hinged and based on the result of analysis, it is designed as per IS: 456 (2000) and IS: 1893 (2002). The parameter varied for the study is the modulus of subgrade reaction of the soil. A comparison of the displacements of the frame and the time period of the whole structure is done.