The construction of soft storey buildings in India has increased for fulfilling the need of parking and other commercial spaces. A soft storey may be present at any floor level in the building. The provision of soft storeys at different floor levels in a building result in reduced stiffness of lateral load resisting elements due to absence of masonry infills.
Based on literature review it was found that limited study has been carried out about new provisions of IS 1893:2016. The focus of this study was to investigate the effect of soft storey and to determine actual magnification factor required for design of a case study. The system was modelled using two editions of IS 1893, one published in 2002 and second in 2016. The presence of infill walls was modelled in ETABS by using an equivalent diagonal strut as per IS 1893:2016 (Criteria for earthquake resistant design of structures. Part 1 General Provisions and Buildings. Bureau of Indian Standards, New Delhi, India, 2016 [
1]), whereas there was no such provision in 2002 (Criteria for earthquake resistant design of structures. Part 1 General Provisions and Buildings. Bureau of Indian Standards, New Delhi, India, 2002 [
2]). In the present study the fifteen-storey structure was analyzed by varying the level at which soft storey was provided. The values of storey stiffness, displacement, drift and time period were calculated using the two editions of IS 1893 (Criteria for earthquake resistant design of structures. Part 1 General Provisions and Buildings. Bureau of Indian Standards, New Delhi, India, 2016 [
1], Criteria for earthquake resistant design of structures. Part 1 General Provisions and Buildings. Bureau of Indian Standards, New Delhi, India, 2002 [
2]) and then compared. The magnification factors required for design of soft storey elements were also evaluated using response spectrum analysis and the significance of diagonal strut method was highlighted.
The present study concluded that modelling the infill walls as equivalent diagonal strut is conservative. The presence of infill walls as per 2016 code resulted in reduced magnification factors required for design of soft storey elements.
