Title: Punching-Shear Behavior of Glass Fiber-Reinforced Polymer-Reinforced Concrete Edge Column-Slab Connections: Experimental and Analytical Investigations
Author(s): Ahmed E. Salama, Mohamed Hassan, and Brahim Benmokrane
Publication: Structural Journal
Appears on pages(s): 147-160
Keywords: edge column-slab (ECS) connections; fiber-reinforced polymer (FRP); high-strength concrete (HSC); moment-to-shear force ratio (M/V); punching shear; shear strength prediction; two-way slabs
This paper presents test results from an experimental program conducted to study the punching-shear response of reinforced concrete (RC) edge column-slab connections (ECS connections) reinforced with glass fiber-reinforced polymer bars (GFRP). Five full-scale ECS connections were tested under vertical shear force and unbalanced moment until failure. Four of the five connections were reinforced with GFRP bars as flexural reinforcement; one connection was reinforced with steel bars for comparison. All slabs measured 2500 x 1350 x 200 mm (98.4 x 53 x 7.9 in.) with a 300 mm (11.8 in.) square column stub protruding 700 mm above and below the slab surfaces. The test parameters were flexural-reinforcement type, concrete strength, and moment-to-shear force ratio (M/V). The test results revealed that all the connections failed by punching shear with no signs of concrete crushing. The high-strength concrete (HSC) directly enhanced the punching-shear capacity, load-deflection response, and initial stiffness of the connections. These connections also evidenced fewer and narrower cracks compared to their counterparts cast with normal-strength concrete (NSC). Increasing the M/V produced significant shear stresses, thereby reducing the vertical load capacity by 31% and 30% for the NSC and HSC connections, respectively. A simple design approach to predicate the punching-shear capacity of FRP-RC ECS connections is proposed. The proposed approach yielded good, yet conservative, predictions with respect to the available test data.