Studying the Influence of the Distribution of Carbon Rods in the Sections of Reinforced Concrete Beams with Hybrid Reinforcement on their Flexural Behavior

The mixed use of steel bars and carbon rods in concrete beams can offer beams with different behaviour from that of steel reinforcement only. This paper studies the case of reinforcing concrete beams with two layers of bars, and the main para­meters investigated are the proportion and the distribution of carbon rods in the cross-section. Four groups containing 12 beams are tested, and each is reinforced with 4 bars located in two layers. The first group includes three control beams reinforced with steel bars, while the second includes three beams reinforced with carbon bars. Each of the third and fourth groups includes three beams reinforced with two steel bars and two carbon bars, whereas in the third group, steel bars are located above carbon ones, but in the fourth group, steel bars are located under carbon ones. Concrete beams reinforced with carbon rods in the second group exhibit a higher load carrying capacity and deflections, compared with other beams. However, the beams in the third and fourth groups have approximately the same load carrying capacity and the same behaviour up to the load level equal to 75% of their load carrying capacity. But after that, the beams in the fourth group become more deformed, compared with those of the third group.