Behavior of Strain Hardening Cementitious Composites in Flexure/Shear

The new generation of fiber-reinforced cementitious composites made with polyvinyl alcohol fibers and high amounts of fly ash shows advantageous mechanical properties in terms of very high tensile strain capacity and ductility. The challenge that remains is to establish pertinent new design rules and analysis procedures and to adapt existing ones specifically tailored to structures made of these materials. In this direction, four-point bending tests were conducted on scaled beam specimens considering several values of shear span aspect ratio in order to determine the behavior of this novel ductile concrete in shear. Tests were conducted on mixes with and without longitudinal and shear reinforcement. It was found that the fiber content had a significant effect on all aspects of mechanical behavior, in terms of strength and ductility. The strength of fiber-reinforced composite beams with longitudinal reinforcement in shear and flexure was interpreted using mechanistic models that rely on the classical beam theory and the strut-and-tie approach. The independent contributions to shear resistance of the fiber-reinforced web, longitudinal reinforcement anchored beyond the critical shear crack, and transverse reinforcement were calibrated to the experimental results in order to establish procedures for evaluating the structural performance of this innovative cementitious material.