The lateral force-resisting system of many buildings in Bangladesh and worldwide comprises masonry-infilled reinforced-concrete frames. Previous studies have demonstrated that an inadvertent (for poor workmanship) or intended gap between the frame and infill can significantly alter the in-plane strength and stiffness of infilled frame system. Only few studies used reinforced-concrete frames. The criteria for the size and position of the gaps were likewise constrained. The main goal of this study is to numerically investigate the impact of the gap between the reinforced-concrete frame and the masonry-infill at various locations and in various magnitudes (i.e., column gap (s), beam gap, and all sides gap). A finite element model of a masonry-infilled reinforced-concrete frame was created using ABAQUS utilizing the macro technique to simulate the masonry panel in order to examine the impact of gaps on the in-plane behaviour and strength of masonry infills bound by frames. The investigation of the global behaviour was carried out in terms of lateral load and story drift response, initial stiffness reduction ratio, and ultimate strength reduction ratio. Investigation results showed that, lateral stiffness and strength decreased by 28-70% and 5-11% respectively, when aforementioned gaps were considered. The reduction trend was validated with experimental results.