The main topic of this thesis is the structural design project of a semi-open steel hall in Zadar and fire design of the structure according to HRN EN 1991-1-2 and HRN EN 1993-1-2. Design of elements in the 'cold state' was also carried out, where the effects of self-weight, wind and snow were considered. In addition to the common actions and the calculation of the fire development in the closed part of the structure, the focus is on the design of the open part of the structure on the real fire. Furthermore, the disposition solution of the structure was made, and the main joints of the frame system were design. The floor plan rectangular hall is 20 m wide and 60 m long, of which the side open part is 25 m long. The roof is gabled at a slope of 10 °, and the height in the eaves is 6 m. The main load-bearing structure consists of a two- hinged portal frame that are spaced 5 m from each other. The structure is designed in S355 steel grade. The fire load in the closed part of the hall is 350 MJ/m2, and the required fire resistance of the structure is R30. Ozone v3.0.4 software package was used to calculate fire development (temperature - time ratio). Considering several different fire scenarios, a complete analysis was made in the SCIA Engineer 19.1 software package. After that, a manual fire resistance check was performed. In addition to modern methods of simulating the development of real fire and the calculation of steel structural elements at elevated temperatures, it has been proven that the considered steel structure without fire protection meets the requirement for fire resistance of R30.