Predicting pull-out behaviour of 4D/5D hooked end fibres embedded in normal-high strength concrete

Previous research (Abdallah et al., 2016) conducted by the authors had proposed an analytical model to predict the pull-out behaviour of 4DH/5DH fibres embedded in ultra-high performance concrete. The present paper is an extension to the prior study and focuses on the pull-out load-slip behaviour of these fibres embedded in normal high strength concrete combinations. Based on experimental investigations, an elastic-plastic moment expression has been proposed to represent the partially plastic hinge formed during pull-out of each circular steel fibre. This prediction takes into account the variation of concrete strength, geometrical and tensile properties of the fibres. Partial deformation in straightening of the hook as well as fibre rupture was also included in the analysis. The model developed is validated against experimental pull-out results of various hooked end fibres, for which reasonable to very good predictions are found.