Experimental tests of two-span continuous concrete deep beams reinforced with GFRP bars and strut-and-tie method evaluation

Abstract

Test results of nine continuous concrete deep beams reinforced with GFRP bars and one specimen reinforced with steel rebars are reported. The investigated parameters included shear span-to-overall depth ratio (a/h), size effect and web reinforcement ratio. Two a/h ratios of 1.0 and 1.7 and three section heights of 300 mm, 600 mm and 800 mm as well as two web reinforcement ratios of 0% and 0.4% were used. The experimental results highlighted that the web reinforcement ratio improved the load capacities by about 10% and 18% for specimens having a/h ratio of 1.0 and 1.7, respectively. Additionally, a considerable reduction in shear strength occurred due to the increase of the section depth from 300 mm to 600 mm. The comparisons between the test results and those calculated using the strut-and-tie methods of the American (ACI 318-2014), European (EC2-2004) and Canadian (S806-2012) codes showed that the American code gave unsafe predictions, while the predictions of the Canadian code underestimated the load capacity of the beams tested. The European code provided the closest predictions to the test results; however, all codes presented do not consider the influence of section depth and/or web reinforcement on the shear strength, the impacts of which were confirmed experimentally.