Fire resistance of reinforced concrete columns with L-, T-, and +-shaped cross-sections

Four full-scale reinforced concrete (RC) columns with L-shaped cross-sections, four full-scale RC columns with T-shaped cross-sections, three full-scale RC columns with +-shaped cross-sections, and one full-scale RC column with a square cross-section were experimentally investigated for fire resistance following the ISO834 standard heating process. The effects of axial load ratio and fire exposure condition on failure mode, axial deformation and fire resistance of the columns were analyzed. The experimental results showed that: (a) when the axial load ratio is 0.55, the fire resistances of the columns with L-, T-, and +-shaped cross-sections subjected to fire on all sides were 60–73% that of the column with the square cross-section. (b) In the case of samples subjected to fire on all sides, the fire resistance of columns with differently-shaped cross-sections increased in the following order: L-shaped cross-section <T-shaped cross-section <+-shaped cross-section. A computer program RCSSCF was developed to calculate temperature, deformation, and fire resistance of the loaded columns with L-, T-, and +-shaped cross-sections. The results of the numerical simulation were compared with those of the full-scale fire resistance tests.