The influence of protective layer debonding on the performance of cfrp-strengthened corroded reinforced concrete beams

Abstract

[Objective] Reasonably and accurately describing the mechanical behavior and failure mechanism of Carbon Fiber Reinforced Polymer(CFRP) when used to reinforce corroded steel-bar concrete bending members is crucial for in-depth research and improvement of CFRP reinforcement technology in enhancing the mechanical performance and durability of corroded steel-bar concrete structures. [Methods] Acoustic emission monitoring technology was employed to conduct bending performance tests on steel-bar concrete beams with different degrees of corrosion which reinforced by CFRP. By comprehensively analyzing key indicators such as deflection, rebar strain, carbon fiber strain, and characteristics of acoustic emission signals, the mechanical characteristics of CFRP-reinforced corroded steel-bar concrete beams were revealed. [Results] The result showed that the effect of CFRP reinforcement was closely related to the degree of corrosion of the steel-bar. Under a determined reinforcement method, as the corrosion rate of the steel-bar increased, the “tension arch” effect was intensified due to the degradation of the bond performance between the steel-bar and concrete, leading to a gradual decrease in the reinforcement effect of CFRP. [Conclusion] The spalling and detachment of the concrete cover made the “tension arch” effect between CFRP and concrete more significant than that of the steel-bar, which had a greater impact on the overall mechanical performance of the test beams. In addition, combining the characteristics of acoustic emission monitoring signals with mechanical test indicators could more comprehensively reflect the mechanical response of the test beams at various loading stages, providing strong technical support for the evaluation and design of CFRP-reinforced corroded steel-bar concrete structures.

Keywords

corroded steel-bar concrete / CFRP / acoustic emission(AE) / “tension arch” effect / deformation / mechanical properties