Shear performance and capacity calculation of steel fiber reinforced recycled concrete deep beams

To promote the application of recycled concrete in engineering, this paper investigates the shear performance of steel fiber reinforced recycled concrete (SFRRC) deep beams. A total of 13 beams were fabricated, and the main design parameters included steel fiber volume fraction, span-to-depth ratio, horizontal web reinforcement spacing, and recycled concrete strength. All beams were subjected to three-point loading using a 10,000 kN electro-hydraulic servo testing machine. The results showed that steel fibers significantly enhance the shear capacity, stiffness, and ductility of recycled concrete deep beams. The shear capacity of a recycled concrete deep beam reinforced with 0.5 % steel fiber volume fraction was 3.5 % higher than that of a natural aggregate concrete beam without steel fibers. When 2.0 % steel fibers were added, the shear capacity of the recycled concrete deep beams increased by up to 45.9 %. Compared to recycled concrete deep beams without steel fibers, the stiffness of the recycled concrete deep beams with steel fiber volume fractions of 0.5 %, 1 %, 1.5 %, and 2 % increased by 7.4 %, 11.4 %, 13.6 %, and 20.4 %, respectively. Based on the cracking strut-and-tie model, a calculation method for the shear capacity of SFRRC beams, which comprehensively considers the effects of steel fibers and recycled aggregates, was proposed and validated using 36 sets of experimental data. The research findings provide a foundation for the practical application of SFRRC deep beams in engineering. • Shear performance of SFRRC deep beams was investigated. • Steel fibers can significantly improve the shear performance of recycled concrete deep beams. • A shear capacity calculation method based on the cracking strut-and-tie model was proposed. • The model's calculation results show good agreement with the test results.