This paper contains the results of fire resistance calculation of reinforced concrete columns with advanced calculation methods. For columns that are tested unloaded, determine the cross-sectional temperature distribution and values of temperature in reinforcement. The fire resistance of columns that have been tested without load is determined according to temperature measurements, with calculation methods according to the requirements of DBN B.1.1-7 andDBN B.1.2-7. According to the tabulated method, the fire resistance of reinforced concrete columns is determined by geometric parameters such as cross-section width, axis distance of the reinforcement, amount of reinforcement, length or height of the element, load level during the fire exposure, heating conditions during the fire exposure (number of fire exposed sides). Accidental combination of actions during the fire situation consists of characteristic values of permanent and variable long-term actions taking into account the safety factor  for the consequence class of the object (CC2) and the type of design situation (accidental). Thermal analysis of the column was performed under conditions of the standard fire exposure. In such conditions it was assumed that the column is exposed to fire with four sides for 120 minutes that corresponds to the required fire resistance class R120. The thermal state of the column was determined using transient thermal models that take into account radiation-convective heat transfer in the ambient from the heat source to the structural surface, convective heat transfer in the structure, radiation-convective heat exchange from the structure to the ambient environment. The residual load-bearing capacity of the reinforced concrete column after the fire exposure was calculated with the reduced cross-section determined using zone method in accordance with the requirements of DSTU-N B B.2.6-197 and DSTU-N B EN 1992-1-2. The fire resistance period of columns for the load-bearing criterion was determined on the basis of the results of of thermal and static analysis.

This paper presents the numerical modelling of the fire exposure on structural element and its static analysis taking account of the material properties reduction due to elevated temperature. The reinforced concrete wall of basement storey was subjected to one side fire exposure. Advanced calculation methods were used to assess the fire exposure on the structural element as most reliable and approximate to fire test results. Thermal analysis was performed with LIRA-CAD software by the simulating of three main heat-transfer ways: thermal conductivity, convection and radiation. As a result of the thermal analysis, temperature distribution in the concrete and reinforcement parts of the structural element cross-section was obtained. The thermal analysis of the wall structural element was performed for 120 minutes in standard fire exposure. Reduction factors for the strength of concrete and reinforcement steel were determined based on the temperature distribution in the wall structural element cross-section. The cross-section is divided into a number of parallel zones of equal thickness where the mean temperature and the corresponding mean compressive strength is assessed according to the Zone method procedure. The fire damaged zone of thickness az at the fire exposed sides and reduced cross-section were obtained. Static analysis of the wall load-bearing capa-city was performed using the procedure applicable for normal temperature design. The Deformation method for normal temperature design taking to account concrete deformation was used. The Deformation method for normal design taken to account concrete deformation at every step of iteration was used. The reduced load-bearing capacity of the fire damaged wall taking into account residual concrete strength was calculated and relevant load-bearing capacity diagrams were determined.