Struts and stress fields with transverse tension and cracks parallel to the direction of compression lead to a reduction of compressive strength in reinforced concrete structures. Biaxial tests on fine‐grained ultra‐high performance concrete (UHPC) and ultra‐high performance fiber‐reinforced concrete (UHPFRC) panels additionally reinforced with steel bars show that this reduction in compressive strength is already pronounced even with small transverse tensile strain and crack widths, but stabilizes for larger tensile strain. A reduction could also be observed with regard to compressive stiffness of the struts, which behave quasi‐linear under compressive loading. Basically, the UHPFRC panels show less reduction in strength and stiffness than the UHPC panels. Compared with the results obtained from the tests on normal‐strength reinforced concrete panels and fiber‐reinforced concrete panels, the reduction of compressive strength is only little larger for UHP(FR)C. Based on the test results, a proposal for modeling the stress–strain behavior of UHP(FR)C in compression–tension stress state is provided.

中文翻译：

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承受横向拉力和裂缝的超高性能（纤维增强）混凝土压杆的结构性能

横向拉伸的支撑杆和应力场以及与压缩方向平行的裂缝会导致钢筋混凝土结构的抗压强度降低。在细颗粒超高性能混凝土（UHPC）和超高性能纤维增强混凝土（UHPFRC）面板上附加了钢筋的双轴测试表明，即使在横向拉伸应变和裂缝较小的情况下，抗压强度的降低也已经很明显宽度，但对较大的拉伸应变稳定。还可以观察到支柱的压缩刚度降低，其在压缩载荷下表现为准线性。基本上，UHPFRC面板比UHPC面板显示出更少的强度和刚度降低。与正常强度的钢筋混凝土面板和纤维增强的混凝土面板的测试结果相比，UHP（FR）C的抗压强度降低幅度很小。根据测试结果，提出了在压缩-拉伸应力状态下模拟UHP（FR）C的应力-应变行为的建议。