EXPERIMENTAL STUDY ON FIRE BEHAVIORS OF RC RESTRAINED BEAMS DURING HEATING AND COOLING PHASES

In order to investigate the fire behaviors of reinforced concrete (RC) restrained beams during heating and cooling phases, eight restrained RC beams were tested in fire with a cooling phase. The influences of some parameters (such as axial/rotational restraint stiffness, load ratio, and heating time) on deformations and internal forces of the restrained beams were discussed. Test results show that: 1) the axial force in restrained beam subjected to heating and cooling processes increases first and then drops gradually; the residual axial force is significant after the cooling phase, and the maximum axial force ratios of the specimens are range from 0.05 to 0.1; 2) the influence of heating time on the mean value of maximum bending moments at the left and right beam ends is limited, implying that the mean value of maximum bending moments reaches within 60 min of heating; and 3) the change of rotational restraint stiffness has little effect on the mean value of maximum additional bending moments at the left and right beam ends.