In this article, the shear behavior of lightweight concrete beams reinforced with glass fiber-reinforced polymer (GFRP) bars is examined. Here, in order to investigate the effect of bar type on the shear strength, the GFRP bar was used as the longitudinal bar. In total, eight concrete beams with a span length of 2 m and section dimensions of 150×250 mm without transverse reinforcement were tested. The parameters under study included the concrete type (lightweight and conventional), shear spans to depth ratio (a/d) (2.5 and 4), bar type (steel and GFRP), and diameter of the longitudinal bars (12 and 16 mm). The results of the tests showed that the failure of the beams under study was of the shear type, as expected. With an increase in the a/d ratio, the shear strength decreased, and more flexural cracks were observed. The shear strength of the lightweight concrete beams was obtained lower than that of the corresponding conventional concrete beams. The beams reinforced with the steel bars demonstrated a higher stiffness relative to the ones reinforced with the GFRP bars. Furthermore, the shear strength results obtained from the tests were compared with those predicted by equations proposed by several codes as well as studies in the literature. The comparison showed good consistency of the experimental results with those predicted by the Canadian code.
