Cracking and yield behavior of reinforced UHPC beams containing steel slag under flexural test

In this paper, the flexural performance of reinforced ultra-high performance concrete (R-UHPC) beams containing steel slag is investigated and the effect of various variables on cracking and yield load are analyzed. First, the cracking, deformation and strain behavior of steel slag R-UHPC beams were investigated by flexural tests, and the role of steel slag powder was analyzed. Then, a characteristic load identification method was proposed and a database of characteristic bending moments was established. The random forest model was used for feature selection to extract the critical variables affecting the characteristic bending moments. Finally, the prediction method of characteristic bending moments was established by cross-section analysis, and the influence of each factor on characteristic bending moments was analyzed. The results show that the addition of steel slag powder decreases the mechanical properties of UHPC, which in turn decreases the flexural behavior of the beam, but the effect on the ultimate load is limited. At the same time, the addition of steel slag powder significantly reduces energy consumption, so the application of steel slag UHPC in beams is feasible. Compared to other variables, the tensile strength of UHPC has a greater effect on the cracking bending moment and the reinforcement ratio has a greater effect on the yield bending moment of the beam.