In the Master thesis the design of the structure of an 8-storey residential building, which is located in the city of Bitola in the Republic of Macedonia, is presented. The structural system of the building is designed as a reinforced concrete (RC) dual system, composed of frames and walls. Due to insufficient conceptual design, the structural system should be considered as torisionally flexible. However, the initial geometry of the building was adopted in accordance to an existing conceptual design, which was performed according to JUS code. In the thesis, the building was designed in accordance to the Eurocode standard. The analyses of the structure were performed using the computer programs Etabs and SAP2000. Particular attention was devoted to seismic analysis of the building, and to the design of a typical frame, main walls and the most loaded slab. For the structural elements under consideration, reinforcement drawings were also created. The results of the analyses indicated relatively large reinforcement ratios in the walls. This can be attributed to large design base shear, which is prescribed for a torsionally flexible system, and the low percentage of walls compared to the area of a plan of the building. A more economical design could be achieved only by changing the conceptual design in order to transform the building to a torsional stiff building. As a consequence, the larger value of the behaviour factor could be taken into account. Considering only minimal changes in the sizes of structural elements, the seismic performance of the building could not be significantly improved, which highlights the importance of adequate consideration of the basic principles of conceptual design in early stages of the design.