The idea of open ground building (OGS) has taken its place in the Indian country due to it provides the parking facility in the ground storey of the building. From the past surveys most of the OGS buildings are failed. The collapse mechanism of such type of building is due to the formation of soft-storey behaviour in the ground storey of this type of building. In the columns higher streses of ground storey under seismic loading due to absence of lateral stiffness and mass. In conventional design practice, only consider structural modelling (bare frame analysis). Design based on such analysis, results in under-estimation of the bending moments and shear forces in the columns of ground storey, and hence it may be one of the reasons responsible for the failures observed. After the Bhuj earthquake took place, the IS 1893 code was revised in 2002, and new design recommendations to address OGS framed buildings. According to clause 7.10.3(a) of the same code states that: “The columns and beams of the soft-storey are to be designed for the multiplication factor of 2.5 times the storey shears and moments calculated under seismic loads of bare frame”. The prescribed multiplication factor (MF) of 2.5, is highly vulnerable for designing the building. This MF value however does not account for number of infill walls present storeys, number of bays, numbers of storeys etc. and hence it is independent of all of the above factors. The main objective of present study is the study of comparative performance of OGS buildings designed according to various MFs using nonlinear analysis. As the more realistic performance of the OGS building requires the modelling the stiffness and strength of the infill walls.
Open ground storey buildings, Magnification factor, Infill walls, Bare frame, Response spectrum analysis, Nonlinear analysis