Experimental study of the influence of inclined pre-cracks on shear behavior of RC beams without transverse reinforcement

Abstract

Extended growth of existing cracks in reinforced concrete (RC) structures may negatively impact structural performance and cause great risks to structural safety. However, the influence of inclined pre-cracks on shear behavior of RC structures as well as the mechanism behind it are still unclear. In this paper, an experimental investigation is conducted in order to study the correlation between inclined pre-cracks and the shear behavior of RC beams without transverse reinforcement. Eight beams with identical geometric designs and different pre-cracking conditions were categorized into four series and successfully tested: (i) reference beams without pre-cracks, (ii) beams with pre-cracks in the bending span induced via loading, (iii) beams with pre-cracks in the shear span induced via loading, and (iv) beams with artificial pre-cracks in the shear span. The deformation and strain fields were measured by digital image correlation (DIC) technique with a strong focus on the shear-transfer mechanism and cracking propagation. The obtained results reveal that inclined pre-cracks in the bending span may not develop into the critical shear crack (CSC) and exert minor effects on the shear capacity. In contrast, pre-cracks near supports within the shear span tend to develop into the CSC and influence its path and kinematics. This further affects the activation of arch action and aggregate interlock, ultimately resulting in a 3–24% reduction in the load-bearing capacity of this series compared to the reference beams. To summarize, this study reveals the relationship between inclined pre-cracks and shear behavior of RC structures, providing new insight for assessment.