Size Effect in Shear Failure of High Strength Concrete Beams without Stirrup reinforced with Basalt FRP Bars

This study investigates the size effect in shear failure of high strength concrete beams without stirrup reinforced with basalt Fiber Reinforced Polymer (FRP) bars. The experimental works include constructing and testing twelve large-scale simply supported beams. The main considered parameters were beam depth (300, 500 and 700 mm), flexural reinforcement ratio and concrete compressive strength. The test results show that there is a considerable size effect in normalized shear strength with average reductions in shear strength of 32.8 and 43.6% when the beam effective depth was increased from 252 to 452 and 635 mm respectively. With increasing beam depth the ultimate deflection and ductility reduced substantially and the shear failure become more brittle. Comparing the experimental with predicted shear strength by seven codes and nine proposed equations from literature showed that the most accurate design equations, are those of Alam and Hussein (2013), Razaqpur and Spadea (2010), Lee and Lee (2014), and CSA (2010, 2012), however in most of the considered equations the degree of conservatism decreased with increasing beam depth. Moreover, comparing the size effect in this study with others from the literature indicated that the size effect is larger in beams reinforced with basalt FRP rebar than glass and carbon FRP rebar, however more studies are needed to confirm this.