The most important assignment of any structural designer is to ensure the structural stability and serviceability of the structure throughout its service life. Due to the variation of magnitude with time, permanent, variable and accidental actions are distinguished. The fire belongs to a set of accidental actions. In the event of a fire, great material damage and loss of human life can occur. Therefore, structural designers in the process of designing structures give considerable importance to the calculation of the resistance of the structure to the action of fire. Within this thesis, the concept of reliability of the steel structure of a multi-story building exposed to fire is processed. The work is divided into the theoretical and practical parts. Within the theoretical part, the fire is analyzed as an accidental effect on the structure. Moreover, several possible ways of analyzing the steel structure exposed to the fire are processed, where special emphasis was placed on the calculation of the resistance of the steel structure to the fire according to EN 1993-1-2. Within the practical part, a statical and seismic analysis of the structure was carried out. Seismic analysis resulted in smaller internal forces of structural elements (due to area of low seismicity), therefore, the sizing of structural elements was carriedout according to static analysis of the structure. The analysis of the fire resistance of the structural elements was carried out by a simplified calculation method using nominal fire. The calculation of the structural elements resistance to fire is determined for unprotected and protected structural elements in the reference period. A natural fire model for a localized fire in case of ignition of one car has also been processed. Dimensioning of the connections of structural elements is shown in the last part of the work. Thethesis includes drawings, a disposition of the structure, overview plans, and structural detailing drawings.