A Model for the Prediction of the Tensile Strength of Fiber-Reinforced Concrete Members, Before and After Cracking

The tensile behavior of concrete or mortar plays an important role for delaying the formation and propagation of cracks, and also for upgrading the bearing capacity of existing concrete and masonry constructions. Although the presence of steel fibers is known to improve, often considerably, the tensile capacity of concrete members, methods for the quantification of this improvement are still limited. For this reason, a model has been developed for the prediction of the tensile strength of steel fiber-reinforced concrete members, as crack opening occurs. Given the geometry and the physical characteristics of reinforced concrete member and fibers, the model predicts: (1) the number of fibers crossing a crack's surface; (2) the distribution of these fibers in terms of (i) the angle a fiber forms with the crack surface (fiber inclination) and (ii) the embedded length of the fiber at both sides of the surface; (3) resistance to crack opening provided by each fiber, in relation to its position and inclination. On the results of the results obtained, the influence of the number of fibers on the reduction of crack widening in concrete or mortar is remarkable and can be estimated with satisfactory precision. In upgrading existing concrete and masonry constructions, this tensile behavior is found to play important role.