Behaviour of RCC beams after exposure to elevated temperatures

Abstract

A study was carried out to generate experimental data on residual strength of reinforced cement concrete (RCC) beams subjected to fire for long duration (exceeding fire resistance). Six RCC beams were cast with similar cross-sectional details, length and grade ofconcrete and clear cover provided to reinforcements. Four beams were exposed to fire for 1 h, 1.5 h, 2 b, 2.5 h duration. Thereafter, five beams were load tested and sixth beam, (ie, beam exposed to fire for 2.5 h) failed in serviceability criterion for its residual deflection due to fire. Some spalling of concrete was observed in the beam exposed to fire for 2.5 h at the time of removal from furnace, which increased with time under normal weathering conditions. The reduction found in initial stiffness of fire exposed RCC beams were more than the reduction in near ultimate stiffness. Also, amount of this reduction in stiffness increased with the increase in fire exposed duration.