Lap shear-prestressed bond test to evaluate prestressed FRP concrete joint

Document Type : Research Note

Authors

1 Department of Civil Engineering, Isfahan University of Technology (IUT). Isfahan, Iran.

2 Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran

3 Department of Civil Engineering, Isfahan University of Technology, (IUT), Isfahan, Iran

10.24200/j30.2024.63429.3273

Abstract

Abstract:

The use of FRP composites as an effective method for strengthening reinforced concrete structures has been a subject of research due to its numerous benefits. A common failure mode in the application of these composites is the debonding of the FRP sheet from the concrete surface, which can sometimes reduce the capacity of these composites to as low as 10% of their total capacity. As a result, researchers have begun to prestress the FRP sheets and strengthen them with prestressed FRP to optimize the efficiency of these materials. A crucial aspect in the strengthening of a reinforced concrete member with an FRP sheet is the examination of the connection behavior between the FRP sheet and concrete. The significance of this issue has led to dedicated research and experimentation in this field. In this study, a prestress-lab shear test was employed for the first time to investigate the bond behavior of prestressed FRP composites-to-concrete joints. Additionally, the particle image velocimetry (PIV) method was used for result analysis. To verify the effectiveness of this method, eight tests were conducted on prism specimens measuring 150×150×350 mm. The strengthening methods of the specimens involved the use of the external bonded reinforcement (EBR) and external bonded reinforcement on grooves (EBROG) methods. Furthermore, the specimens were prestressed at different levels, including 0%, 20%, and 30% of the ultimate strain of FRP composites. This study examined the specimens in terms of bond strength capacity, failure mode, and stress and strain distribution on the joint surface. The results showed that prestressing increased the bond strength by 70% in the EBR method. Moreover, the bond strength of EBROG specimen with 20% prestressing increased by 123% compared to the control specimen. These findings indicate that prestressing using the EBROG method is a viable technique for enhancing the performance of FRP-to-concrete joints.

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Sharif Journal of Civil Engineering

Articles in Press, Accepted Manuscript
Available Online from 19 March 2025

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