An infill frame is defined as a dual system, which consists of bricks or concrete blocks filling the inter-planar voids between lower and upper beam and space between side columns of reinforced or steel frame. Despite the fact that infill enhances both strength and stiffness of the moment resisting frames; their role is ignored in the design due to insufficient knowledge of the composite behaviour of infill and frames. It is credible, that a major portion of the lateral load is shared by the infill. This paper deals with translating existing experimental data into analytical methods. To understand the behaviour of brick masonry, a G+1 structure was modelled in ANSYS and results were obtained. The present study is also aimed at finding the effect of openings in brick walls and captive column effect. When infill walls are omitted in the bottom storey, a soft storey is formed compared to stiffer stories at top. By response spectrum analysis it has been proved that the structural time period for frame with infill decreases by 2 to 3 times compared to frames without infill. The results showed that the soft storey building frame attracts 40% more shear force than frame excluding soft storey effect. The variation in time period at different mode shapes, with and without infill is presented in the paper. The phenomenon of captive column was replicated and formation of short column is shown in the pilot study.