EXPERIMENTAL RESEARCH AND NUMERICAL ANALYSIS OF THE FLEXURAL BEHAVIOR OF RC CONTINUOUS T-BEAM WITH HIGH-STRENGTH BAR AFTER FIRE

An experimental study on the flexural behavior of reinforced concrete continuous T-beams with high strength bar at room temperature and after fire was conducted. The static loading test was accomplished for two control specimens. Three continuous beams were tested under fire with 30 min, 60 min and 90 min respectively according to ISO 834, and then the static loading test was accomplished after the beams were cooled to room temperature naturally. The temperature distribution of cross-section was measured during heating and cooling. The damage of beams after fire, and the deformation and failure mode of beams in the static loading test were also observed. The deteriorating laws of the flexural stiffness, ductility index, yield load and ultimate load of specimens after fire were studied and compared with the control specimens. For the temperature field of cross-section, the external temperature was high and the internal temperature was low during heating, but the external temperature was low and the internal temperature was high during cooling. When the exposed time was extended, the yield load and the ultimate load of beams had an parabolic decrease. The decrease of flexural stiffness was greater than that of the yield load and the ultimate load. The ductility index also had an obvious decrease. The numerical analysis results of temperature field and the flexural behavior after fire of RC continuous T-beam with high-strength bar agree well with the test results, which is expected to provide advice to appraisal and evaluation of RC structure after fire.