A numerical approach for the evaluation of the structural redistribution coefficient KRd

Structures made of a material with a very high standard deviation, as fibre reinforced concrete, show a too safe prediction of the maximum bearing capacity when derived from characteristic values identified by means of small specimens. This is emphasized when the structures are characterized by a large redundancy. To this regards full-scale slabs on ground having a high grade of redundancy are considered as reference test. Italian Standard and more recently Model Code 2010 have introduced a coefficient (structural redistribution factor) able to take into account the reduced variability of the mechanical strength when associated to a large volume involved in the failure process or when the structure is able to significantly redistribute stresses favouring the average strength rather than the minimum one. A numerical procedure taking into account the real heterogeneity of the mechanical characteristics in the structure, is for the first time introduced for the redistribution factor evaluation.