Enhancement of cantilevered RC beams exhibiting inadequate lap spliced reinforcement using sustainable reinforced ECC layers

Abstract

Designguidelines require an adequate overlap length for reinforcing bars, especially in extended spans of elements constructed from Reinforced Concrete (RC). Insufficient overlap can have adverse effects on key characteristics like bending strength and deformability of RC beams. The potential danger of failure in such elements is a significant concern as is considered a potential threat, and this study addresses it through experimental identification and numerical analysis to be mitigated carefully in this study to enhance the safety and sustainability of buildings to mitigate the risk of failure. The current investigation is centered on investigating the structural behavior of cantilevered RC beams exhibiting inadequate overlap between reinforcing bars in the hogging moment region. These beams have been strengthened through the application of ferrocement layers of Engineered Cementitious Composite (ECC). The experimental study consisted of eleven beams, which were categorized into four groups and subjected to bending loads until they reached failure. The research assessed various factors, such as the casting method (whether cast-in-situ or precast), the installation technique (involving the use of epoxy, or epoxy with anchors), and the length of the ECC layer. This layer was configured to have a length of 30Ø, 40Ø, and 50Ø, with Ø representing the diameter of the reinforcing bars along the zone subjected to hogging moments. According to findings, strengthening of specimens exhibiting insufficient steel overlap through an ferrocement ECC layer exhibited an improved overall structural behavior compared to the defective control beam. The most significant enhancement in both failure mode and load-deflection behavior was observed in beams strengthened through the incorporation of a cast-in-situ ECC layer with anchor bolts. Additionally, augmenting the strengthening length not only increased the initial stiffness of the reinforced beams but also enhanced their energy absorption capacity. Furthermore, the study involved the construction of a numerical simulation employing the Finite Element Method (FEM) simulating the observed behavior in experimentally tested beams. The model's precision was validated through a comparison of its results with the experimental data, revealing a satisfactory level of accuracy.