Abstract
This paper aims to study the flexural behavior of concrete beams reinforced with hybrid combinations of GFRP/steel bars. To this purpose an experimental program was carried out on four concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) and twelve hybrid GFRP/steel Reinforced Concrete (RC) beams. Flexural behavior of the tested beams such as stages of response, failure modes, crack patterns, stiffness, toughness and ductility were analyzed. The experimental results showed that depending on GFRP/steel reinforcement configurations, the behavior of hybrid GFRP/steel RC beams undergoes three or four stages, namely: pre-cracking stage; after concrete cracking and before steel yielding; post-yield stage of the steel bar until peak load and failure stage. Totally six failure modes of hybrid RC beams are reported depending on reinforcement rations and configuration. The effect of reinforcement configuration and ratio of GFRP to steel (ρg) on the crack patterns, stiffness, ductility and toughness of hybrid RC beams are significant. Based on the non-linear deformation model, an analytical model has been developed and validated to determine the steel yielding moment and ultimate moment of hybrid GFRP/steel RC beams. It could be seen that the experimental values were in good agreement with the predicted values.
Highlights
Damage, reduced service life and failure of concrete structures reinforced with steel bars are inevitably the most common consequences of steel reinforcement corrosion
The load-deflection curves of all tested hybrid Glass Fiber Reinforced Polymer (GFRP)/steel Reinforced Concrete (RC) beams (Figure 5) show that the behavior of hybrid GFRP/steel RC beams from start of loading until complete failure could be divided into three stages or four stages depending on reinforcement ratios and configurations: first stage - pre-cracking stage; second stage after concrete cracking and before steel yielding; third stage - post-yield stage of the steel bar until peak load and fourth stage – failure stage
This paper analyzes the influence of reinforcement ratios as well as configurations to the flexural behavior of hybrid GFRP/steel RC beams and GFRP RC beams
Summary
Damage, reduced service life and failure of concrete structures reinforced with steel bars are inevitably the most common consequences of steel reinforcement corrosion. Several studies on establishing the model for predicting moment capacity, deflection, curvature of hybrid FRP/steel RC beams and crack widths were presented [6, 9,10,11] These researches revealed that the GFRP to steel ratio affects importantly the flexural performance and crack development of hybrid reinforced concrete beams. The rest of the article is structured as follows: Section 2 describes the experimental program of the hybrid GFRP/steel and GFRP RC beams; Section 3 presents test results and discussion in terms of global behavior, crack patterns, flexural stiffness, ductility index, toughness and moment carrying capacity in detail; Section 4 illustrates an analytical model to estimate the steel yielding moment and moment carrying capacity of hybrid beams; and the conclusions are given in the final section.
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