A new bond model for reinforcing bars in steel fibre reinforced concrete

The addition of fibres to concrete would significantly improve the bond between the concrete and the rebars embedded therein. However, it remains a difficult task to model the rebar bond stress-slip relation of fibre reinforced concrete (FRC). In the present research, the effects of adding steel fibres on the rebar bond properties have been studied by conducting pull out tests of rebars embedded in steel FRC. Then, a new rebar bond model for steel FRC is developed by modifying the existing one for plain concrete in Model Code 2010. Besides incorporating the effects of steel fibres for extended application to steel FRC, a finite initial bond stiffness (the initial bond stiffness in Model Code 2010 is infinite) is adopted in the model for more realistic bond-slip analysis. The coefficients in the model are determined by analysing the experimental results from present study and the available data published in literature. Interestingly, it is found that the concrete strength and steel fibres have synergistic effect on the bond performance of steel FRC.