Numerical analysis of rubberized engineered cementitious composite (RECC) RC beams under impact loads

The environmental hazards of unrecycled rubber products and the current movement of developing more sustainable materials shed the light on utilizing recycled rubber as aggregates in concrete. The use of recycled scrab tire rubbers as aggregates in concrete can not only reduce environmental damages but also enhance the concrete’s dynamic mechanical properties such as an increase in the overall compression strain at failure and the material’s fracture energy. Previous research has investigated using rubber aggregates in concrete for reinforced concrete (RC) structural elements under static loads. However, this study aims to utilize the improved dynamic properties of concrete with rubber to resist impact loads on beams. This article presents a novel numerical investigation of the static and impact loading response of rubberized engineered cementitious composite (RECC) beams. A three-dimensional (3D) non-linear finite element (FE) model was constructed to analyze the behavior of conventional concrete (NC), crumb RECC, and powder RECC beams under impact loads. The study employs an accurate FE model that captures the non-linear behavior of RECC materials, including their properties in compression and tension, and the strain rate effect. Moreover, the strength and toughness of concrete beams can be improved by using a hybrid section of NC and RECC. Therefore, in the current study, the behavior of crumb or powder RECC layers in compression or tension sides of NC beams was studied under impact loads as well as the effect of low-impact energy, high-impact energy and the impactor nose type (hemispherical and flat-nose cylinder) on RECC beams. The outcomes of the FE model demonstrated good agreement with the available experimental results from the literature. The dynamic response of RECC beams was analyzed using FE model outputs, including time histories of impact forces, reaction forces, internal forces (shear force and flexural moment), mid-span displacements, and dissipated energy. Results indicated that RECC enhanced the performance of RC beams under impact loads. The tension performance of RC beams under impact loads was enhanced by using RECC on the tension side or in full depth since RECC limited flexural cracks and improved flexural capacity. In Comparison with NC Beams, the RC beams mid-span displacement was reduced and the energy dissipation capacity of concrete was improved when using RECC under low and high impact energies. CRECC on the compression side or in full depth improved the distribution of impact force on the NC and reduced compression damage.