article · Frontiers in Materials
Experimental and numerical investigations examined methods to improve the shear performance of defective reinforced concrete beams lacking shear stirrups. Ten beams were evaluated under three-point testing, including two control specimens and eight beams strengthened with externally bonded strain-hardening cementitious composite layers in various configurations. Evaluated setups included single-sided, two-sided, and strip applications using mechanical anchors. Strengthening with a single-sided composite layer containing vertically bent bars efficiently addressed shear reinforcement degradation. Applying three composite strips partially across compromised beams yielded a modest effect on initial stiffness while increasing cracking and ultimate loads by 46 percent and 42 percent, respectively. Increasing the treatment to four bolted strips further improved load-deflection behaviour, serving as a feasible alternative to continuous coverage across the defective zone. A developed numerical model successfully predicted crack progression, deflection, and ultimate capacity in close agreement with experimental findings.
Reinforced concrete structures missing critical internal shear stirrups face a severe risk of sudden structural failure. Demonstrating that externally bonded composite strips and mechanical anchors can restore load capacity provides practical retrofit options. These techniques help maintain building safety, avoid catastrophic structural failures, and extend the operational life of compromised infrastructure without requiring full component replacement.
This technique is aimed at structural engineering practitioners, repair contractors, and infrastructure maintenance organisations seeking targeted retrofits for defective concrete elements. Currently at an applied testing stage based on laboratory beam specimens and numerical simulations, the research shows that bolted strip configurations can lower material usage compared to full coverage. Progression toward industry adoption will require moving beyond laboratory testing to standardised application guidelines.
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This study delves into the efficacy of external strengthening methods in improving the shear behavior of defected reinforced concrete (RC) beams that lack shear stirrups, utilizing both experimental and numerical methodologies. Failure risk of such beams is a potential threat which is mitigated carefully to increase building safety and sustainability to avoid risk of construction failure. Ten RC beams underwent three-point experimental testing to assess the influence of the strengthening scheme and the presence of mechanical anchors. Two beams were designated as control specimens, while eight beams were strengthened with the application of additional strain-hardening cementitious composite (SHCC) layer in various configurations. These configurations encompassed single-sided, two-sided, and strip applications, with the inclusion of mechanical anchors. The study found that employing a single-sided SHCC, incorporating vertically bent bars into the RC beam, is recognized for its efficient alleviation of degradation in shear reinforcement. The incorporation of three SHCC strips to partially reinforce the compromised beams demonstrated a modest impact on the initial stiffness. Nevertheless, noteworthy enhancements of 46% and 42% were observed in both cracking and ultimate loads, respectively. Furthermore, increasing the number of the SHCC strips to four resulted in a more significant improvement in the load–deflection responses. Enhancing the compromised beams by applying four SHCC strips to the beams using bolts offers a feasible alternative to the configuration where SHCC was uniformly attached along the entire defected zone. Moreover, a numerical model was created to simulate the tested beams. The model effectively anticipated the progression of cracks, ultimate capacity, and deflection, indicating excellent agreement with the experimental observations.
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DOI: 10.3389/fmats.2024.1373292
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