ABSTRACT
In the field of steel fibres reinforced concrete, there exists a large variety of fibre geometries governing the properties of fibre reinforced concrete.
It is now well accepted that when a wiredrawn non-straight steel fibre is being pulled out from a matrix, it straightens. This permits to develop a micro-mechanical model, based on the friction behaviour at the fibre-matrix interface and on the anchorage behaviour which provides plastic strains in the steel.
It is shown that both these basic phenomena interact. Sensitivity studies made with the theoretical model show that the anchorage component is the most important phenomenon which governs the pullout behaviour of the fibre.
From this analysis, we conclude that the critical size of the non-straight fibre cannot be given only in terms of its critical length any longer.
Finally, we evaluate the crack opening displacement at which the peak pullout load is theoretically obtained. It appears that the mobilization of the fibre is quite instantaneous, but, as a consequence of the crack plane surface effect, the behaviour of the fibre in concrete macrocracks is more complex.
