Numerical modelling of shear crack angles in FRP shear-strengthened reinforced concrete beams

The shear crack angle is a key parameter in the calculation of the fibre-reinforced polymer (FRP) contribution to the shear capacity of a shear-strengthened reinforced concrete beam. In this study, a new approach is developed to estimate the shear crack angles for such a beam. The approach is based on the FRP/concrete interface response. A non-linear finite element model was developed to simulate the behaviour of six beams grouped in three sets according to their dimensions. One unstrengthened beam of each set was used as a benchmark and its behaviour was compared to that of a beam strengthened with a U-wrap scheme. It was found that the numerical model is able to successfully simulate the behaviour of the shear-strengthened beams. The numerical predictions compare very well with previously published experimental data in terms of load-deflection relationships and carbon FRP (CFRP) axial strain profiles along the sheet length. The analysis of the slip profiles along the CFRP strip is helpful to understand the bond behaviour between the concrete and CFRP strips. The interfacial slip profiles are used to predict the shear crack angle along the shear span, and these predictions agree very well with the experimental measurements. The numerical results give failure modes that are identical to those obtained experimentally.