Shear Performance of RC Bridge Girders Reinforced with Carbon FRP Stirrups

Abstract

One of the main components in girder-type bridges is bridge girder. This paper presents experimental data on the behavior and shear strength of concrete bridge girders reinforced with carbon fiber-reinforced polymer (CFRP) stirrups. A total of four large-scale reinforced concrete beams with a total length of 7,000 mm and a T-shaped cross section were constructed and tested up to failure. The test variables were the type and ratio of shear reinforcement (stirrups). The test beams included three beams reinforced with sand-coated CFRP stirrups of 9.5-mm-diameter spaced at d/2, d/3, and d/4 (where d is the beam depth) and a control beam reinforced with conventional steel stirrups of 9.5-mm-diameter spaced at d/2. The geometry of the test prototypes were selected to simulate the New England Bulb Tee (NEBT) beams that are being used by the Ministry of Transportation of Québec, Canada. As designed, three beams failed in shear due to CFRP stirrup rupture or steel stirrup yielding. While, the forth one, reinforced with CFRP stirrups spaced at d/4, failed in flexure due to yielding of longitudinal reinforcement. The test results were compared to predictions provided by different codes and design guidelines. The current ACI 440.1R-06 design method provides conservative predictions; however, the CAN/CSA S6-06 and JSCE 1997 underestimate the contribution of the FRP stirrups due to low strain limits.