11.Fire resistance analysis of reinforced concrete simply supported beams

Abstract:

Based on ABAQUS finite element software, the sequential thermal coupling method was been adopted to analyze the temperature, deflection, and stress changes of the mid span section of reinforced concrete simply supported beams under different working conditions under fire. The results show that the cross-sectional temperature of a simply supported beam under fire exhibits a gradient distribution. Simple supported beams with reinforcement ratios of 0.9%, 1.3%, and 1.7% reach their fire resistance limits at 46.7 min, 57.5 min, and 89.3 min, respectively. Simply supported beams with protective layer thicknesses of 20 mm, 30 mm, and 40 mm reach their fire resistance limits at 32.2 minutes, 42 minutes, and 57.5 minutes. The fire resistance limit time of a simply supported beam with a span to height ratio of 8 is increased by 56 minutes compared to a simply supported beam with a span to height ratio of 12. The Mises stress curves on the longitudinal reinforcement show an upward trend followed by a downward trend, and the higher the temperature, the lower the stress on the longitudinal reinforcement when the simply supported beams reach its fire resistance limit.

Keywords: temperature field;simply supported beam;deflection;fire resistance limit;stress