This paper investigates the feasibility and flexural behavior of reinforced concrete beams internally prestressed with straight unbonded aluminum alloy tendons by testing five partially prestressed beams and one reference beam. For each beam specimen, load-deflection curves, failure modes and cracking behavior, the relationship between load and strains in steel and prestressing aluminum alloy tendons were examined and analyzed. In particular, the effects of effective prestress, combined reinforcement index (CRI), and partial prestressing ratio (PPR) on flexure of concrete beams were discussed. The test results indicated that the spacing and width of concrete cracks of prestressed beams containing the same amount of bonded longitudinal steel reinforcement decreased with the increase of effective prestress, and the combined reinforcement index governs flexural behavior of the prestressed beams. The flexural crack width and displacement ductility exhibited a reduction with the increase of CRI. In addition, an analytical model was established to calculate the flexural strength and corresponding deflection at midspan of the concrete beams internally prestressed with unbonded aluminum alloy tendons by suggesting a new simplified curvature distribution, which is more accordant with the original curvature distribution. The proposed model provides a relatively good estimation of the flexural capacity and midspan deflection of the prestressed beams.

本文通过测试5条局部预应力梁和1条参考梁，研究了在内部用直的无粘结铝合金钢筋预应力的钢筋混凝土梁的可行性和抗弯性能。对于每个梁试样，检查并分析了钢-预应力铝合金筋的荷载-挠度曲线，破坏模式和开裂行为，荷载与应变之间的关系。特别是，讨论了有效预应力，组合钢筋指数（CRI）和部分预应力比（PPR）对混凝土梁弯曲的影响。试验结果表明，随着有效预应力的增加，包含相同数量纵向粘结钢筋的预应力梁的混凝土裂缝的间距和宽度减小，组合的钢筋指数决定了预应力梁的抗弯性能。弯曲裂纹宽度和位移延展性随着CRI的增加而减小。此外，建立了一个解析模型，通过建议一种新的简化曲率分布，计算出与原始曲率分布更相符的抗弯强度和内部预应力混凝土梁的中跨处相应的挠度。所提出的模型对预应力梁的抗弯能力和中跨挠度提供了相对较好的估计。建立了一个解析模型，通过建议一种新的简化曲率分布，以更符合原始曲率分布，计算无粘结铝合金腱内部预应力混凝土梁的抗弯强度和相应的挠度。所提出的模型对预应力梁的抗弯能力和中跨挠度提供了相对较好的估计。建立了一个解析模型，通过建议一种新的简化曲率分布，以更符合原始曲率分布，计算无粘结铝合金腱内部预应力混凝土梁的抗弯强度和相应的挠度。所提出的模型对预应力梁的抗弯能力和中跨挠度提供了相对较好的估计。