Bond of NSM systems in concrete strengthening – Examining design issues of strength, groove detailing and bond-dependent coefficient

• Published in: Construction & building materials Vol. 47; pp. 1512 - 1522
• Main Authors: Lee, Dongkeun, Cheng, Lijuan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2013; Elsevier B.V
• Subjects: Analysis; Bond strength; Bond-dependent coefficient; Concrete; Design; Fiber-reinforced polymer (FRP); Groove detailing; Near-surface mounted (NSM); Properties; Reinforced plastics; United States; Design; Bond strength; Near-surface mounted (NSM); Bond-dependent coefficient; Fiber-reinforced polymer (FRP); Groove detailing
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2013.06.069

•Current guide generally provides a reasonable design value for average bond strength.•Improvement is needed for analytical/semi-empirical average bond strength models.•Optimum groove dimensions are proposed for preliminary design purpose.•Equations for estimating effective strain of CFRP round rods and strips are proposed. Research on the strengthening technique using near-surface mounted (NSM), fiber-reinforced polymer (FRP) composites has substantially advanced the knowledge on the bond-related issues such as bonded length, failure mechanisms, groove and bar dimensions, and local bond-slip behavior. In this study, several important design-related parameters that deserve more attention are carefully examined, including average bond strength, groove detailing, and bond-dependent coefficient. The accuracy of the existing analytical and semi-empirical models for average bond strength is assessed using the experimental data available in the literature. Optimum groove dimensions and a new empirical model for the bond-dependent coefficient are also proposed to complement the existing design guide for the NSM FRP technique used in concrete strengthening.