Study of debonding in CFRP-strengthened beams and contribution of anchorage systems
The rehabilitation of buildings and infrastructure has gained importance in recent decades. Carbon Fiber-Reinforced Polymers (CFRP) are effective for strengthening Reinforced Concrete (RC) structures due to their mechanical strength, corrosion resistance, and lightweight properties. The Externally B...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/692490 |
| Acceso en línea: | http://hdl.handle.net/10803/692490 |
| Access Level: | acceso abierto |
| Palabra clave: | Formigó armat Hormigón armado Reinforced concrete Polímers reforçats amb fibra de carboni Polímeros reforzados con fibra de carbono CFRP strengthening Reforç adherit externament Refuerzo adherido externamente Externally Bonded Reinforcement (EBR) Desvinculació Desvinculación Debonding Reforç adherit externament a les ranures Refuerzo adherido externamente a las ranuras Externally Bonded Reinforcement on Grooves (EBROG) Adhesió híbrida de polímers reforçats amb fibra de carboni Adhesión híbrida de polímeros reforzados con fibra de carbono Hybrid Bonding FRP Ancoratges Anclajes Anchors 620 |
| Sumario: | The rehabilitation of buildings and infrastructure has gained importance in recent decades. Carbon Fiber-Reinforced Polymers (CFRP) are effective for strengthening Reinforced Concrete (RC) structures due to their mechanical strength, corrosion resistance, and lightweight properties. The Externally Bonded (EB) method, known for its ease of installation and effectiveness, improves the performance of RC structures. However, flexural reinforcement often leads to premature debonding of the FRP from the concrete, limiting the use of FRP properties. To address Intermediate Crack Debonding (ICD), several predictive approaches have been developed, though they impose strict strain limits on FRP. To mitigate premature debonding in EB-FRP strengthened flexural members, anchorage of the CFRP laminate has been a focus of investigation. Effective techniques such as Externally Bonded Reinforcement on Grooves (EBROG) and Hybrid Bonding (HB)-FRP have shown promise. However, experimental and analytical/numerical studies in this area remain limited, indicating the need for further research. This thesis investigates ICD in EB-FRP strengthened RC beams from theoretical and experimental perspectives. It analyses formulations from the literature and compares theoretical predictions with four-point bending test results on RC beams with varying concrete strengths and steel reinforcement ratios. The study includes an experimental database of 68 RC beams, showing that models predict ICD failure modes accurately. The effectiveness of Externally Bonded Reinforcement on Grooves (EBROG) and Hybrid Bonding (HB)-FRP methods in preventing ICD is examined through bond and flexural tests. Results indicate that both methods enhance the performance of EB-FRP, although existing prediction models underestimate the bending capacity for EBROG. A numerical model is developed to simulate ICD for various bond-slip laws, applicable to different strengthening techniques. This model determines the maximum tensile force the FRP laminate can effectively transfer between two consecutive cracks, addressing the excessive tensile forces between cracks that lead to ICD failure. This maximum force depends on the bond behaviour of the FRP-concrete interface, which varies with the chosen strengthening technique. Therefore, the proposed model allows for the implementation of diverse shapes of bond-slip laws corresponding to different strengthening methods. It is specifically developed to solve the governing equation of the bonded joint using numerical procedure based on the finite difference method. The proposed model is validated by applying the bond-slip laws calibrated from the single-shear tests to the flexural test results, demonstrating accurate prediction of ICD failure for EB, EBROG and HB-CFRP specimens |
|---|