Shear testing of different type and size of GFRP reinforcing bars

Shear testing of Glass Fiber-Reinforced Polymer (GFRP) reinforcing bars can be considered for material specifications, quality control, quality assurance and structural design purposes. The shear testing procedure requires the cutting blades of the shear device to match exactly the bar's diameter, therefore, for each different bar diameter new blades would have to be manufactured. In this research, a developed device to test GFRP bars in shear is manufactured based on both ASTM D7617 and CSA S806-12 standards. The paper aims to provide information about the significance of shear testing of GFRP bars and the potential outcomes of this type of test. For that purpose, different types of GFRP bars (straight and bent) provided by two different suppliers (sand/ribbed coating), are studied. The conducted tests consider GFRP reinforcing bars with measured diameter 18 mm. Then, the bars are “shaved” using a lathe machine to exclude the external coating and their diameter is reduced to 15.5, 13.5 and 10 mm. The idea of testing GFRP bars with reduced diameter that excludes the effect of the outer treated surface can possibly provide more unbiased information for quality control. Finally, discussion on the failure modes and stiffness is presented for both straight and bent bars.