<p>CFRP cords utilized as external concrete reinforcement follow the curvature in flexural deformation due to their flexibility, preventing debonding that occurs with pre-pregnated CFRP bars. This study investigated the CFRP cord utilization for revitalizing cracked, non-collapsed haunch beam-to-column joints through experimental and numerical methods on large-scale specimens, enhancing the direct applicability of the findings to real-world structures. Since tensile reinforcement has yielded, the cords took a substituting role in the energy dissipation and ductility refinement, restoring the integrity of the system. Two members with haunch angle variations were loaded until tensile-steel yielding, straightened, and epoxy injection retrofitted. Three CFRP cords were attached to the tensile area, and the member was reloaded. The rehabilitation effectiveness was performed by comparing the behavior to two uncracked interchangeable members. A numerical model was developed, and a multi-criteria sensitivity analysis was conducted to evaluate the shifting of the most significant failure behavior parameters. It was demonstrated that the concrete ultimate strain and the initial and post-crack stiffness modulus in compression were the most influential factors, while for non-CFRP-reinforced identical members, the residual stress coefficient and ultimate stress in tension were dominant. The reinforced member was restored and improved significantly in terms of load-carrying capacity of 27% and 32% for <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$14^\circ$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mn>14</mn> <mo>∘</mo> </msup> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$26.5^\circ$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>26</mn> <mo>.</mo> <msup> <mn>5</mn> <mo>∘</mo> </msup> </mrow> </math></EquationSource> </InlineEquation> haunch, respectively, with the reduced initial stiffness of 30–67%. The findings provide validated, practical strategies for engineers seeking to extend the service life of existing concrete infrastructure, moving beyond laboratory-scale proof of concept to demonstrate a viable and effective conservation technique.</p>

External CFRP cord beam-to-column joint reinforcement

期刊论文
发表日期：

2025年11月2日

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Bobby Rio Indriyantho,
Blinka Hernawan Prasetya,
Purwanto Purwanto,
Sri Tudjono,
Ay Lie Han,
Viktor Mechtcherine,
Buntara Sthenly Gan

摘要

CFRP cords utilized as external concrete reinforcement follow the curvature in flexural deformation due to their flexibility, preventing debonding that occurs with pre-pregnated CFRP bars. This study investigated the CFRP cord utilization for revitalizing cracked, non-collapsed haunch beam-to-column joints through experimental and numerical methods on large-scale specimens, enhancing the direct applicability of the findings to real-world structures. Since tensile reinforcement has yielded, the cords took a substituting role in the energy dissipation and ductility refinement, restoring the integrity of the system. Two members with haunch angle variations were loaded until tensile-steel yielding, straightened, and epoxy injection retrofitted. Three CFRP cords were attached to the tensile area, and the member was reloaded. The rehabilitation effectiveness was performed by comparing the behavior to two uncracked interchangeable members. A numerical model was developed, and a multi-criteria sensitivity analysis was conducted to evaluate the shifting of the most significant failure behavior parameters. It was demonstrated that the concrete ultimate strain and the initial and post-crack stiffness modulus in compression were the most influential factors, while for non-CFRP-reinforced identical members, the residual stress coefficient and ultimate stress in tension were dominant. The reinforced member was restored and improved significantly in terms of load-carrying capacity of 27% and 32% for $14^\circ$ $14^{\circ}$ and $26.5^\circ$ $26 . 5^{\circ}$ haunch, respectively, with the reduced initial stiffness of 30–67%. The findings provide validated, practical strategies for engineers seeking to extend the service life of existing concrete infrastructure, moving beyond laboratory-scale proof of concept to demonstrate a viable and effective conservation technique.