Interlaminar shear strength of hybrid fiber reinforced polymer bars: Based on proposed and existing test methods

In this study, a new test method, namely, the direct shear method was proposed to obtain the interlaminar shear strength (ILSS) of hybrid fiber reinforced polymer (HFRP) bars, which combined the advantages of standard methods in ASTM-D4475 and ASTM-D3914. The test device matched with this new method was also developed. Meanwhile, to verify the validity of this method, a total of 165 specimens were prepared to test the ILSS of carbon/glass-HFRP bars based on the proposed and other two existing standard methods, respectively. Additionally, the effects of the volume fraction and distribution pattern of carbon fiber, and the volume fraction of resin on the ILSS of carbon/glass-HFRP bars were systematically studied. The results show that the ILSS of carbon/glass-HFRP bars slowly decreases with the increase in the volume fraction of carbon fiber, and the ILSS of carbon/glass-HFRP bars with the dispersed distribution of carbon fiber is averagely 14.7% higher than that of specimens with the centralized arrangement of carbon fiber. The ILSS of carbon/glass-HFRP bars first rises and then reduces with the increase in the volume fraction of resin until it is nearly 40%.