Use of fiber orientation factor to determine residual strength of steel fiber reinforced concrete

Abstract

The post cracking behavior of steel fiber reinforced concrete (SFRC) subjected to direct tensile stresses is strongly related to the distribution and orientation of the fibers in the crack plane, which can be precisely determined using images obtained by computerized axial tomography (CAT). However, these images require processing to relate them to the residual resistances of the SFRC.The objective of this paper is estimating the residual strength of SFRC cores using the fiber orientation coefficient determined from CAT images.Using the orientation coefficient as a single and simple parameter, the percentage of fibers with complete and sufficiently anchored hooks has been determined, which allows (1) estimating the number and orientation of the active fibers in any section of the specimens and (2) establishing the probability that the fibers are active depending on the specimen and the fibers' geometry.Then, the residual strengths of SFRC are computed using the Laranjeira superposition model, obtaining differences with the experimental results, mainly due to the dispersion of the number of fibers in the fracture plane, the different contribution of the fibers and the contribution of the cut fibers.