Abstract The study aimed to obtain the composite beams with high flexural capacity by using the high compressive strength and deformation capacity of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC). For this purpose, the composite RC beams consisting of UHPFRC layer in the compressive side and Normal Strength Concrete (NSC) in the tensile side were produced and the four-point bending tests were carried out on the beams. By making parametric study for the ratio of tensile reinforcements (ranging from 1.8% to 5.0%), highest ratio where sufficient ductility can be acquired in the beams were determined. Two different thicknesses (one-fifth of the beam height/one-third of the beam height) of UHPFRC layer were applied in the compressive side of the composite beams in order to determine the appropriate thickness. The flexural behavior characteristics (ductility, capacity, stiffness) of the composite beams were evaluated by comparing the pure NSC beams (reference beams) with the same properties. With the use of UHPFRC in the compressive side of the beams, significant advantages have been acquired in ductility, flexural capacity and stiffness compared to the NSC beams. However, the main advantage of the composite application was that it allows the use of very high amount of tensile reinforcement in the beam. The study indicated that it was possible to increase tensile reinforcement ratio of the composite beams up to 5% without using compressive reinforcement. Thus, the ductile composite beams with high flexural capacity were produced with the use of economical amount of UHPFRC. The UHPFRC layer thickness of one-third of the beam height was appropriate for the overall flexural performance at this type of composite beam.

中文翻译：

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超高性能纤维混凝土层高筋复合梁的抗弯性能

摘要 研究旨在利用超高性能纤维混凝土（UHPFRC）的高抗压强度和变形能力，获得具有高抗弯能力的组合梁。为此，生产了由受压侧的 UHPFRC 层和受拉侧的法向强度混凝土 (NSC) 组成的复合 RC 梁，并对梁进行了四点弯曲试验。通过对受拉钢筋比例（1.8%~5.0%）进行参数化研究，确定了梁获得足够延性的最高比例。两种不同厚度（梁高的五分之一/梁高的三分之一）的 UHPFRC 层被应用于复合梁的受压侧，以确定合适的厚度。通过比较具有相同特性的纯 NSC 梁（参考梁）来评估组合梁的弯曲行为特性（延展性、承载力、刚度）。通过在梁的受压侧使用 UHPFRC，与 NSC 梁相比，在延展性、抗弯能力和刚度方面获得了显着优势。然而，复合材料应用的主要优点是它允许在梁中使用非常高的抗拉强度。研究表明，在不使用受压钢筋的情况下，可以将组合梁的抗拉配筋率提高至 5%。因此，使用经济量的 UHPFRC 生产出具有高抗弯能力的延性组合梁。