Contribution of steel fibers to the flexural and shear behavior of RC beams damaged by alkali-silica reaction

Abstract

The study of damage processes in concrete and their effects on the residual properties represents a key point related to the service life of reinforced concrete (RC) structures. The use of steel fibers in RC beams mainly improves the cracking control and the shear bearing capacity. Considering the shear behavior, the presence of fibers not only leads to partial or total substitution of secondary reinforcement, but they can also result in a modification of the failure behavior from a shear failure (brittle) to a bending (ductile) one. The contribution of fibers on flexural and shear behavior of sound and damaged RC beams was investigated using alkali-silica reaction as a damaging tool. First, the evolution of deformations and cracks were measured on creep tests of RC beams with and without fibers and reactive aggregates. Second, the flexural and shear behavior of damaged and undamaged beams incorporating steel fibers were compared. Results showed that alkali-silica reaction damage can provoke a reduction of RC beam ductility, while the flexural strength is preserved. Regarding shear, it was observed that even in damaged concrete, fibers were able to control the crack propagation and increase the bearing capacity.