Transverse Shear Testing of GFRP Bars with Reduced Cross Sections

Shear testing of glass fiber–reinforced polymer (GFRP) bars can be considered for material specifications, quality control, quality assurance, and structural design purposes. ASTM and the Canadian Standards Association (CSA) specify the testing apparatus and the procedure to test fiber-reinforced polymer (FRP) matrix composites, in which the principal variables are the size (diameter) and type of the FRP bars. This study develops a device to test GFRP bars in shear based on both ASTM and CSA standards. The paper provides 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 are studied. Two test series are considered. The first examines straight and bent bars from two different companies, and tests two different diameters of the GFRP bars. The straight bars are tested with and without their outer coating (provided by the companies) and the bent bars are tested in their straight portion. The same bars are tested in shear after being in an alkaline solution (pH 13) for 5 months (150 days) at 60°C. The second test series considers GFRP bars of various diameters (original GFRP bars are shaved). The main objective of this work is to propose a shear testing protocol for GFRP bars of various diameters by reducing the number of cutting blades of the shear testing device. Finally, the failure modes and the significance of stiffness are discussed.