Unified Analytical Approaches for Determining Shear Bond Characteristics of FRP-Concrete Interfaces through Pullout Tests

Abstract

The pullout test is a conventional test method for calibrating interfacial shear bond characteristics of Fiber Reinforced Polymer (FRP)-concrete interfaces. However, due to the small bending stiffness of FRP sheets/strips and the highly non-linear interface fracturing mechanism, a well-recognized analytical approach to the accurate interpretation of the pullout test results remains to be achieved despite extensive studies particularly when the aim is to calibrate a local bond stress-slip model, which is necessary for developing bond strength and anchorage length models avoiding the use of empirical formulations. This paper introduces a newly developed non-linear bond stress-slip model for analyzing full-range strain distributions in FRP and shear bond stress distributions in the interface bond layer during pullout tests, along with a new anchorage length model and bond strength model that were developed accordingly. Compared with other existing bond models, the bond model described here has two advantages besides its simplicity: (1) it incorporates the most important interface parameter, the so-called interfacial fracture energy, in all analytical processes and links it successfully with all other important bond parameters; (2) it is a general and unified approach that allows for the first time consideration of the effects of the adhesive bond layer in non-linear analysis of FRP-concrete interfaces. Further, a unified bond stress versus slip expression is formulated to show the differences in local bond stress-slip relationships at the loaded and free ends in pullout tests, so that the effects of the bond length used in a pullout test on the calibration of the interfacial bond stress-slip model can be clarified. The reliability of all proposed models is verified through a comprehensive comparison of the experimental and analytical results.

Mechanical Properties of Newly Developed Heat-Resistant FRP Bars

“…The bond strength of aramid fiber-PH FRP bars at high temperature was lower than that of carbon fiber-PH FRP bars, because the heat resistance of aramid fiber is lower than that of carbon fiber. It has been demonstrated by others that the bond strength of FRP bars strongly depends on the glass transition temperature (GTT) of a matrix resin (Freismanis et al1998, Katz et al 1999, Katz et al 2000, Mutsuyoshi et al 2004, and Dai et al 2006. In addition to the results of previously reported papers, the heat resistance of the fiber itself will be important when the heat resistance of the matrix resin is improved.…”

Bond-Slip Model for FRP Laminates Externally Bonded to Concrete at Elevated Temperature

“…1 is valid for all locations of a sufficiently long bond length (Dai et al 2005(Dai et al , 2006. Therefore, Eq.…”

Flexural behaviour of reinforced concrete beams strengthened with a composite reinforcement layer: BFRP grid and ECC

“…pure flexural debonding of a plate end located in a pure bending region (simply 'flexural debonding') and pure shear debonding of a plate end subjected to a 9 high shear force but little or no moment (simply 'shear debonding') [33][34][35][36][37][38][39][40][41][42][43]. For a simply-supported CRL strengthened RC beam, the shear debonding can be considered as the control debonding failure if the bond length of CRL is enough (e.g.…”