The main purpose of this study is to carry out the 2d nonlinear transient heat analysis of a chosen reinforced concrete cross-section, which is exposed to standard fire, by using simplified, finite difference and finite element method. In the finite element analyses, it is considered that the thermal properties of concrete and reinforcing steel vary as depending on temperatures in time domain. According to results drawn this study, it is put forward some conclusions and recommendations concerning the fire design of reinforced concrete structures.