On the design response of a FRC statically undetermined structure

Fibre reinforced concrete is a concrete with a diffused reinforcement based on fibre pull-out resistance and its toughness in tension is strongly affected by fibre distribution. The material response of a representative volume is significantly affected by the uncertainties related to fibre location and number: only a homogeneous distribution of fibres can guarantee an isotropic behaviour, but in any case its mechanical behaviour dominated by mode I failure, identified by means of a bent notched beam, shows a large standard deviation. By the way, a structure characterized by a significant capability to redistribute stresses and large fracture volume at the onset of collapse can reduce the sensitivity to the high standard deviation and exhibits a bearing capacity aligned to the average mechanical properties of the composite. In the paper several approaches to compute the coefficient that quantifies this structure ability, KRd, are proposed, taking as a reference cases a slab on ground and an elevated slab.