Combined effect of handmade CFRP strip stirrups and forta-ferro fibers on shear behavior of concrete beams

In an attempt to find a non-corrosive stirrup as an alternative to steel stirrup in concrete structures under harsh environments, manual fabrication of fiber-reinforced polymer (FRP) strip stirrups is becoming increasingly popular to address premature failure in pultruded FRP stirrups in concrete beams. This study is the first to address the shear behavior of concrete beams with forta-ferro and handmade FRP strip stirrups. Here, the percentages of forta-ferro fibers added in the concrete mixes were 0.3 and 0.6% by total concrete volume, and the stirrups material was carbon FRP (CFRP). Six series of concrete beams were tested under a four-point bending load to examine the effect of adding fibers and stirrups on the shear behavior of concrete beams. It was found that incorporating forta-ferro fiber causes an increased ultimate load-bearing capacity, ultimate shear load, and deflections at the peak and failure points of concrete beams. An increased fiber content leads to an increase in these properties of concrete beams. The results also showed that, for a given fiber content, concrete beams with CFRP stirrups develop higher ultimate load-bearing capacity (10–33%), ultimate shear load (10–33%), and deflections at the peak (8–22%) and failure points (6–34%) compared to those without stirrups. It is also shown that the proposed model provides an accurate prediction of the shear capacity of fiber-reinforced concrete beams with stirrups. Positive effects of combining forta-ferro fiber and handmade CFRP stirrups in improving the shear resistance as well as the deformability of concrete beams were observed, which is promising.