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UBC Theses and Dissertations

Bond behaviour of fibre reinforced polymer (FRP) rebars in concrete Quayyum, Shahriar


Recently, fibre reinforced polymer (FRP) rebars have been extensively used in construction instead of steel rebars due to their non-corrosive nature and high tensile strength. Bond between FRP rebars and concrete is a critical design parameter that controls the performance of reinforced concrete members at serviceability and ultimate limit states. In order to prevent a bond failure, an adequate anchorage length should be provided. The anchorage length is derived using a bond stress-slip ( ) constitutive law. The objective of this study is to investigate the effect of different parameters such as the type of fibre, the rebar surface and the confinement provided by the transverse reinforcement on the bond behaviour of FRP rebars in concrete. Based on the analysis, a generalized bond stress-slip relationship will be developed and a new design equation for the required anchorage length of FRP rebar in concrete will be derived. A database was created on the bond stress-slip behaviour of FRP rebars in concrete from the available literature up to 2009. The data was statistically analyzed to investigate the effect of the different parameters on the bond performance of FRP rebars. It was observed that an increase in the confinement provided by the transverse reinforcement increased the bond strength of FRP rebars in concrete. This signifies that the presence of transverse reinforcement affects the bond behaviour of FRP rebars in concrete and hence, it should be taken into consideration while developing design equations for FRP rebars. Type of fibre and rebar surface does not affect the bond stress, but the latter affects the slip corresponding to the peak bond stress. Based on the results, a nonlinear regression analysis was performed to develop the bond stress-slip model for splitting mode of failure and a design equation for determining the development length of the FRP rebars in concrete was derived. The proposed development length equation can save about 10%-15% of the development length than that required by different code equations. This can save a considerable amount of FRP materials, which will eventually reduce the overall cost of construction and thereby, encourage the use of FRP reinforcing bars in the construction of concrete structures.

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