Experimental Research on Fire Performance of Hybrid Fiber Concrete Corbels for Flue Plate

To improve the fire safety of corbels for flue plates, six corbels were designed and fabricated. For the test group, corbels under constant load were heated according to the standard fire temperature-rise curve for 120 minutes, followed by natural cooling. After that, static loading destructive tests were conducted with corbels not subjected to high temperatures as the control group. Failure processes of the corbels were observed. The hybrid effects of steel fibers and polypropylene fibers were explored. The results show that: The steel-polypropylene hybrid fiber concrete corbels for flue plates are superior to plain concrete corbels in terms of delaying the temperature rise, enhancing the anti-spalling performance, and other aspects. Under the effect of two-hour heating, the corbels did not show obvious displacement or overall collapse. After being heated and loaded, the corbels did not show the characteristics of flexural failure or shear failure, but their internal reinforcement bar plantings exhibited a bond-slip failure mode. Residual bearing capacities of the corbels with double-doped fiber, single-doped fiber, and plain concrete after high temperature were 85.71%,79.08% and 64.90%, respectively. After being exposed to high temperature, the bonding performance of the planted bars decreased, and the slopes of the load-displacement curves were all slightly larger than those under normal temperature conditions. The strain of the inclined section satisfied the strain characteristics of the strut-and-tie model.