Steel fiber and bond–slip mechanism degradation in fiber concrete subjected to thermal loading: experiments with heated fibers

Fiber pullout is the main mechanism of local failure in steel fiber concrete (SFC) structures (SFCS). Degradation of the steel hooked-end fiber and concrete bond–slip mechanism in heating was investigated in the article. The fibers were heated to temperatures of 20, 100, 200, 400, 500, 600, 800, and 1000 °C and then mechanically tested. Were obtained heated fibers the yield stress, strength, and geometry change. These data were used in numerical modeling. The second fibers part was used in pull-out experiments. Was shown, the fiber pull-out mechanism changed for fiber heated to temperatures higher than 500–600 °C. In the part of the SFCS volume close to the heated surface, the fibers bridging the cracks lose the ability to fail by pulling out of the concrete and collapse due to fiber rupture. Others, with fibers pulling out of concrete. The fiber debonding, friction, and deformation were investigated both numerically and experimentally.