Flexural performance of concrete beams reinforced with steel–FRP composite bar (SFCB) was investigated in this paper. Eight concrete beams reinforced with different bar types, namely one specimen reinforced with steel bars, one with fiber-reinforced polymer (FRP) bars and four with SFCBs, while the last two with hybrid FRP/steel bars, were tested to failure. Test results showed that SFCB/hybrid reinforced specimens exhibited improved stiffness, reduced crack width and larger bending capacity compared with FRP-reinforced specimen. According to compatibility of strains, materials’ constitutive relationships and equilibrium of forces, two balanced situations, three different failure modes and balanced reinforcement ratios as well as analytical technique for predicting the whole loading process are developed. Simplified formulas for effective moment of inertia and crack width are also proposed. The predicted results are closely correlated with the test results, confirming the validity of the proposed formulas for practical use.

中文翻译：

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钢-FRP复合筋混凝土梁的抗弯性能

本文研究了钢-FRP复合钢筋（SFCB）加固的混凝土梁的抗弯性能。测试了八种用不同钢筋类型加固的混凝土梁，即一个用钢筋加固的标本，一个用纤维增强聚合物（FRP）加固的标本，和四个用SFCB加固的标本，而最后两个用混合FRP /钢棒加固的标本进行了测试。测试结果表明，与FRP增强的样品相比，SFCB /混合增强的样品显示出更高的刚度，减小的裂缝宽度和更大的弯曲能力。根据应变的相容性，材料的本构关系和力的平衡，开发了两种平衡情况，三种不同的破坏模式和平衡的配筋率以及预测整个加载过程的分析技术。还提出了有效惯性矩和裂纹宽度的简化公式。预测结果与测试结果紧密相关，证实了所提出公式的实用性。