Behavior of Glass Fiber Reinforced Polymer (GFRP) Reinforced Concrete T-Beam Under Shear

Abstract

Abstract : Corrosion is one of the significant disadvantages of steel reinforcement, especially when exposed to extreme environments. One alternative solution is Glass Fiber Reinforced Polymer (GFRP), which is known for its high strength-to-weight ratio and good corrosion resistance. However, since its mechanical properties, such as modulus of elasticity, differ from those of normal steel, several studies have been conducted to investigate the shear behavior of rectangular beams reinforced with GFRP. In contrast, the shear behavior of GFRP-RC T-beams has not yet been fully explored. This study investigated the shear behavior of seven GFRP-reinforced T-beams without transverse reinforcement. The investigation was conducted in two parts; the first part was carried out experimentally in the University of Bahrain structural engineering lab, while the second part was a Finite Element Analysis (FEA) simulation. In the experimental part, seven T-beams were constructed and tested to failure. All the beams were reinforced with GFRP and had constant cross-section and length Besides, all the specimens had no shear or top reinforcement. The seven beams were divided into three groups; one parameter varied in each group while all other parameters were kept constant. The test parameters were the shear span-to-depth ratio (a/d), which included 2.0, 2.7, and 3.5; concrete compressive strength (fc'), which included approximately 40, 50, and 60 MPa; and longitudinal reinforcement ratio (p), which were 0.7, 1.1, and 1.5%. The test results of this study are demonstrated in the form of mode of failure, ultimate strength, load-deflection behavior, and crack pattern. Furthermore, the experimental ultimate strengths were compared to the predicted shear capacity by the American Concrete Institute (ACI 440.1R-15), the Japan Society of Civil Engineers (JSCE 1997), the Canadian Guideline (CSA S806-12), and ISIS Canada Research Network (ISIS 2007). Additionally, the proposed models by Alam (2010) and Tureyen et al. (2006) were included in the comparison. The outcomes of the experimental study showed that changing the three parameters had a significant effect on the ultimate load, crack pattern, and load-deflection behavior. At the same time, the mode of failure remained the same. In addition, it was found that the Canadian Guideline (CSA S806-12) and Alam's (2010) equations predict the shear strength of GFRP-RC T-beams with good accuracy and consistency On the other hand, the FEA was performed using Abaqus software. Simulated results are compared with experimental results to evaluate the software's accuracy in predicting the shear strength, load-deflection behavior, crack pattern, and failure mode. The modeled beams were simulated using the same mechanical properties used in the experimental study. A concrete damage plasticity model was used to model all seven beams. Two models were developed for each beam, each with a different tension-stiffening model, while all other properties remained unchanged. It was found that the model's predictions of the first cracking load and mode of failure fairly agreed with the experimental results. However, the models did not show accurate results regarding ultimate load and deflection behavior for all the beams. Finally, using two models for each beam showed that the tension-stiffening model significantly affects the model outcomes.