Modellazione numerica del comportamento post-fessurativo di elementi tesi in c.a. fibrorinforzato

In this work, the behaviour of steel fibre reinforced concrete elements subjected to tension is investigated, focusing the attention on the post-cracking stage. As known, the presence of fibres in the concrete matrix determines a more distributed crack pattern, which is usually characterized by narrower, more closely spaced cracks. This post-cracking behaviour is primarily due to the combination of two main mechanisms, that are tension softening, related to the bridging effect provided by fibres across crack faces, and tension stiffening between steel bars and surrounding concrete, which is in turn modified by the presence of fibres. The influence exerted by fibres on structural response has been here investigated through a NLFE procedure, by adopting 2D-PARC constitutive relation for SFRC elements, which allows to separately model each resistant contribution to strength and stiffness, through the implementation of proper laws. The effectiveness of the proposed procedure has been then verified by modelling some experimental tests carried out on SFRC tension ties at the University of Brescia.