Strengthening effects of DFRCC layers applied to RC flexural members

Ductile Fiber Reinforced Cementitious Composite (DFRCC) features a superior strain capacity of 5-6% under tensile loading. However, the strengthening effect of DFRCC on the flexural performance of RC beams is not clearly understood at present. In this study, we numerically investigate the DFRCC strengthening effect as applied to the tension region of RC beams. More specifically, numerical simulations are carried out for four-point bending RC beams strengthened with a cover thickness of DFRCC and with twice the cover thickness at the bottom tension section of the composite beam. To determine the effects of strain capacity and the strain-hardening slope of DFRCC, numerical simulations are carried out with DFRCC strain capacities ranging from 1% to 5%. From these studies, it is shown that the load carrying capacity and displacement at failure are influenced by the strain capacity and strain-hardening slope of DFRCC, but not to a significant degree. DFRCC strengthening on a tension zone can reduce both stress levels and stress concentrations in the reinforcement and can reduce crack width. It also can delay flexural failure of the structure due to the damage-tolerant behavior of DFRCC.