Post-cracking behaviour of steel fibre reinforced concrete

Recently, RILEM TC 162-TDF has proposed equivalent,f eq , and residual,f 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 eq andf R parameters are evaluated. In series of specimens reinforced with fibres of a distinct length/diameter ratio, similar values off eq andf R parameters were obtained in these series. Although a strong correlation betweenf eq andf R was determined, a larger scatter off R values was observed thereby revealingf 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, ɛ pcr , and the crack opening displacement,w, (ɛ pcr =w/L p ) which is useful for evaluating the crack opening when numerical strategies based on a stress-strain approach are used. The obtainedL 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.