A predictive model for modulus of rupture of hybrid fiber-reinforced concrete from fiber-matrix bond resistance

The modulus of rupture of strain-hardening hybrid fiber-reinforced concrete (SHFRC) was estimated using bond resistance of fiber pullout testing in this paper. The hybrid fibers included long steel fiber mixed with short steel fiber. The long steel fibers were long smooth fiber (denoted LS), hooked A fiber (denoted HA), and hooked B fiber (denoted HB); their lengths and types were dissimilar but had the same fiber fraction of 1.0 vol.%. The short steel fiber was smooth type (denoted SS) with three volume fractions of 0.5%, 1.0%, and 1.5%. The resistance of single fiber pullout tests from the available publications was employed to estimate the modulus of rupture of SHFRCs based on the proposal of the predictive model and equations. The estimated and tested results were comparatively compared and discussed.