Residual Load Bearing Capacity of Reinforced Concrete Frames after Fire

Abstract

Estimating the residual strength of fire-exposed reinforced concrete (RC) structures is of great importance in determin-ing whether the cooled structure is safely functional or immediate repair is needed. This paper describes the results of experimental and numerical investigations on fire and post-fire structural responses of a 2-story moment-resisting RC frame test specimen. The lower story of the test specimen, which was subjected to service loads, was heated for 60 min-utes in accordance with the ISO-834 standard fire test. The test specimen exhibited a satisfactory structural performance during the fire course and considerably recovered much of its pre-fire deflection state when cooled. To investigate the re-serviceability and residual load bearing capacity of the cooled test specimen, a destructive cyclic vertical loading was conducted. A detailed 2D finite element model was developed as well. By comparing the test and analysis results, it was found that due to the fire damage the test specimen lost 30% of its load bearing capacity. The proposed numerical mod-elling approach in this study predicted considerably well the post-fire residual strength of the test specimen.