A State-of-the-Art Review on Debonding Failures of FRP Laminates Externally Adhered to Concrete

Abstract

There is significant concern in the engineering community regarding the safety and effectiveness of fiber-reinforced polymer (FRP) strengthening of RC structures because of the potential for brittle debonding failures. In this paper, previous research programs conducted by other researchers were reviewed in terms of the debonding failure of FRP laminates externally attached to concrete. This review article also discusses the influences on bond strength and failure modes as well as the existing experimental research and developed equations. Based on the review, several important conclusions were re-emphasized, including the finding that the bond transfer strength is proportional to the concrete compressive strength; that there is a certain bond development length that has to be exceeded; and that thinner adhesive layers in fact lower the chances of a concrete-adhesive interface failure. It is also found that there exist uncertainty and inaccuracy in the available models when compared with the experimental data and inconsistency among the models. This demonstrates the need for continuing research and compilation of data on the topic of FRP's bond strength.

Pull-out Strengths of GFRP-Concrete Bond Exposed to Applied Environmental Conditions

“…(1) recommended by Chen and Teng (2001). Effective bond length can be defined as the active length for transferring of most of the interfacial stress from FRP sheets to concrete and beyond this length failure load does not increase (Ouezdou et al 2009;Kang et al 2012). The bond length much longer than the effective bond length was chosen considering the possibility of increase in effective bond length due to environmental conditions and to keep the provision for the development of the full capacity of bond in that case.…”

Relationships between interfacial shear stresses and moment capacities of RC beams strengthened with various types of FRP sheets

“…Numerous experimental results [1][2][3][4] have revealed that the composite behavior of flexural members externally reinforced with FRP ends with brittle failure due to FRP debonding. For avoiding such brittle failure, Attari et al [5] evaluates different strengthening configurations to improve ductility of RC beams externally strengthened with FRP sheets.…”

Fatigue Assessment Model of Corroded RC Beams Strengthened with Prestressed CFRP Sheets

“…Externally bonded carbon fiber-reinforced polymer (CFRP) sheets have been widely used to restore or increase the capacities of reinforced concrete (RC) beams due to their advantages including their low weight, high strength and stiffness, high durability, and ease of application (Kang et al 2012;Ouezdou et al 2009;Grelle and Sneed 2013;Ren et al 2015). Many studies have been conducted to study the effect of CFRP sheets on the performance of RC beams (Al-Rousan and Issa 2011;Oudah and El-Hacha 2013a, b;EISafty et al 2014;Kang et al 2014).…”