In this paper, the response of regular concrete space frames subjected to gravity and blast loads for a six-storey building of 18 m high for a charge weight of 100 kg TNT at a 40 m range is studied. The type of blast chosen is a surface blast. Five different types of frames, skeleton frame (SFR), skeleton frame with the stiffness of slab (SFRS), skeleton frame with the stiffness of slab and 230 mm thick infill walls (SFRSWs 1), skeleton frame with the stiffness of slab and 150 mm thick infill walls (SFRSWs 2), and skeleton frame with the stiffness of slab and 115 mm thick infill walls (SFRSWs 3) were modelled and analyzed using STAAD Pro by converting the peak reflected blast pressure into equivalent static pressure by using the dynamic load factor. As the storey level increases the lateral displacements, shear force, and bending moment decrease due to a decrease in the impact of the blast at higher stories. The incorporation of infill walls in SFRSW1, SFRSW2, and SFRSW3 type frames shows a significant reduction in the lateral displacements due to the increase of stiffness when compared with SFR type frames.