The purpose of this work was to assess the influence of several parameters on the fire resistance of steel and composite steel-concrete columns in buildings. The contact with brick walls, stiffness of the surrounding structure, load level, and slenderness of the columns, were the target of the study. Experimental tests were performed on steel H columns embedded on walls, bare steel H columns and composite steel-concrete partially encased H columns with restrained thermal elongation. Results of the experimental tests were compared with numerical studies, with the purpose of providing valuable data for the development or improvement of analytical designing methods. A geometrical and material non-linear analysis with imperfections was performed with the finite element code ABAQUS. The major outcomes of this research work were proposals for the assessment of the temperature evolution within the cross-section of unevenly heated steel columns in contact with walls, proposals for the calculation of the critical temperatures and fire resistance of steel bare columns, and plastic axial force – bending moment diagrams for steel beam columns at elevated temperatures.