The equi-biaxial tensile properties of strain-hardening UHPFRC are determined and investigated based on an original analytical inverse analysis of results from ring-on-ring tests. First, the analytical inverse analysis method is developed based on the elastic slab bending and yield line theories. Using this method, a new objective criterion for the determination of the elastic limit stress of strain-hardening UHPFRC is provided, and a point-by-point inverse analysis is used to obtain the strain value at the end of hardening. This method reduces uncertainties regarding assumptions and avoids any iterative procedures. The inverse analysis results are put into perspective with experimental evidence, particularly based on DIC measurements. Moreover, the uniaxial tensile properties are also derived from the inverse analysis of 4PBT results and compared with the equi-biaxial tensile properties from the proposed inverse analysis. The inverse analysis results show a 18% lower elastic limit stress, and almost equivalent tensile strength of UHPFRC subjected to equi-biaxial stresses, compared with the corresponding values from uniaxial stress. Moreover, a relatively small equi-biaxial strain at the end of hardening is highlighted.

中文翻译：

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通过环对环试验确定应变硬化 UHPFRC 的等双轴拉伸性能的解析逆分析

应变硬化 UHPFRC 的等双轴拉伸性能是根据环对环试验结果的原始分析逆向分析确定和研究的。首先，基于弹性板弯曲和屈服线理论开发了解析逆分析方法。利用该方法，为确定应变硬化UHPFRC的弹性极限应力提供了新的客观判据，并通过逐点逆分析得到硬化结束时的应变值。这种方法减少了关于假设的不确定性并避免了任何迭代程序。逆向分析结果与实验证据相结合，特别是基于 DIC 测量。而且，单轴拉伸性能也来自 4PBT 结果的逆向分析，并与建议的逆向分析中的等双轴拉伸性能进行比较。逆向分析结果表明，与单轴应力的相应值相比，承受等双轴应力的 UHPFRC 的弹性极限应力低 18%，拉伸强度几乎相等。此外，强调了硬化结束时相对较小的等双轴应变。