Tests for flexural behavior of damaged concrete beams without web reinforcement strengthened with HDC under repeated load

Here, 10 severely damaged concrete beams without web reinforcement were strengthened by using high ductility concrete (HDC) with different thicknesses. The normal section bending tests under repeated load were conducted to study effects of HDC with different thicknesses on flexural load-bearing capacity and deformation performance of damaged beams without web reinforcement. In tests, beams' crack distribution state and load-displacement curve were observed. The test results showed that the failure mode of concrete beams strengthened with HDC can change from brittle failure to ductile one, and their load-bearing capacity, ductility and energy dissipation capacity are significantly improved; compared with the beam with HDC reinforcement layer thickness of 0 cm, load-bearing capacities of beams with HDC thickness of 1 cm, 1.5 cm and 2 cm are increased by 19.8%, 32.7% and 46.3%, respectively, while their residual deformations are reduced by 8.96%, 13.3% and 20.47%, respectively. According to loading test results and the method of the curve stress figure of compression zone being equivalent to rectangular stress figure, a simple and practical ultimate load-bearing formula of damaged concrete beams without web reinforcement strengthened with different HDC thicknesses under repeated load was derived, and its calculation values agree better with test ones. © 2021, Editorial Office of Journal of Vibration and Shock. All right reserved.