An Analytical Study of Shear Transfer Mechanisms in Macro-synthetic Fibre Reinforced Concrete

Several researches have demonstrated the effectiveness of fibres to provide post-cracking strength to concrete elements. This is due to the potential of fibres to bridge the crack faces and continue transferring stresses along the shear crack by different shear transfer mechanisms. Several models have been stablished in order to explain the mechanical action of fibres in a shear crack, most of them explained as a function of parameters such as the fibre type, dispersion, inclination, aspect ratio or pull-out stress of the fibre. However, these models have been stablished only for steel fibres, which limits their use to different fibre's materials. Within this framework, the present research first investigates the different shear transfer mechanisms acting in a shear crack, and evaluate the possibility of characterize the fibre shear transfer mechanism by means of the residual flexural tensile stresses (RFTS). For this, an analytical model that involves the transfer mechanism acting in a shear crack is developed. Analytical results are compared against experimental results obtained after testing 20 pre-cracked push-off specimens of plain concrete and macro-synthetic fibre reinforced concrete. Results evidence the great differences among aggregate interlock models available in the literature against the existing differences among the fibre ones. Finally, the feasibility of using RFTS to characterize the contribution of fibres to transfer shear stresses is observed.