This study aims to quantify the effect of designing a masonry-infilled RC building using the bare frame (BF) on the seismic performance of an RC building with soft ground story (SGS). Buildings with infilled walls at each story (B1) and with infilled walls except the ground story(B2) were considered. With the software ETABS, the rebar was designed using the BF model, then an equivalent brace simulating the infilled wall was added to each beam-column frame for advanced analysis, including the elastic force analysis and the nonlinear pushover analysis combined with capacity spectrum method. The performance ground acceleration (PEGA) of B1 and B2 buildings were quantified. It shows that the BF model certainly resulted in more conservative design when the infilled walls were uniformly distributed along the building height. For buildings with SGS, designing rebar using the BF model will not lead to soft story damage if the building is well designed with present building codes. However, for existing buildings with SGS and its shear rebar was poorly designed, soft story effect may control the damage of the building.