Post-cracking behaviour of steel fibre reinforced concrete

Recently, RILEM TC 162-TDF has proposed equivalent,f ^sub eq^, and residual,f ^sub R^, flexural tensile strength parameters to characterize and simulate the post-cracking behaviour of steel fibre reinforced concrete (SFRC) structures. In the current work, more than two hundred flexural tests are carried out according to the RILEM TC 162-TDF recommendations and the corresponding values off ^sub eq^ andf ^sub R^ parameters are evaluated. In series of specimens reinforced with fibres of a distinct length/diameter ratio, similar values off ^sub eq^ andf ^sub R^ parameters were obtained in these series. Although a strong correlation betweenf ^sub eq^ andf ^sub R^ was determined, a larger scatter off ^sub R^ values was observed thereby revealingf ^sub eq^ to be more appropriate for design purposes. A numerical strategy involving a cross sectional layered model and an inverse analysis was developed to evaluate the post-cracking stress-strain and the stress-crack opening diagrams for the tested SFRC. This strategy was also used to determine a relation between the post-cracking strain, ^sup pcr^, and the crack opening displacement,w, (^sup pcr^=w/L ^sub p^) which is useful for evaluating the crack opening when numerical strategies based on a stress-strain approach are used. The obtainedL ^sub p^ values range from half the specimen cross section height to half the distance between the tip of the notch and the top of the cross section.[PUBLICATION ABSTRACT]