Seismic performance evaluation of masonry infill RC frame considering soil-structure interaction

The structural damage due to recent seismic events in Nepal has led to a dire need for studies considering soil-structure interaction (SSI) as the majority of designers still adopt conventional design principles. These damages may be the result of the conventional fixed base method's failure to take into account the underlying soil properties. Post Mw 7.8 Gorkha earthquake, revised Nepal National Building code NNBC 105:2020 has classified soil types based on the rigidity of the soil. A comparative analysis is carried out using linear-static and nonlinear static (Pushover) analysis considering the fixed and flexible base of a masonry infill RC frame. The seismic performance parameter evaluated for a target inelastic drift of 2% are in terms of their fundamental time period, peak floor displacement, inter-storey drift ratio (IDR), ultimate load carrying capacity and yield mechanism. The consideration of SSI drastically influenced the fundamental time period, peak floor displacement and IDR with decreasing rigidity of soil. The fixed base structure exhibited a higher ultimate load-carrying capacity than the flexible base structure for all soil types. The masonry infill dissipated the seismic energy by the failure of the majority of struts. Furthermore, the post-yield behaviour of all models highlighted that the damage level of RC frame and masonry infill elements were higher for fixed base.