Localization and Size Effect of Failure of Concrete Structures Subjected to Compression

受压混凝土结构破坏的局部化和尺寸效应

• 批准号: 12450176
• 负责人: NIWA Junichiro
• 金额: $ 6.66万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450176/
• 关键词: Concrete; Localization of Failure; Size Effect; Compressive Fracture Energy; Length of Failure Zone; Volume of Failure Zone; Deep Beam; Shear Failure; Concrete; Localization of Failure; Size Effect; Compressive Fracture Energy; Length of Failure Zone; Volume of Failure Zone; Deep Beam; Shear Failure

When concrete is failed by compression, the failure does not happen throughout the whole body but it concentrates only in some portion of concrete in the post-peak region. By the localization of the failure in compression, the existence of the size effect in structural concrete subjected to compression can be explained.In this study, the uniaxial compression test of concrete in which the cross-sectional shape, the ratio of height and cross section width are parametrically changed has been carried out in order to quantitatively clarify the localization effect. Based on the measured results of local strain, the local energy absorption has been quantitatively evaluated. According to this measurement, it has been clarified that the localization happens for the compression failure of the concrete when the ratio of the height and the cross section width increases to some extent. And, it is found that the localization length (the length of the failure region) can be evaluated using the side l … More ength of the square having the same cross sectional area as the original cross section. In addition, it is found that the absorbed energy per unit volume of failure region (the compression fracture energy) can be evaluated as the function of the compressive strength of concrete. In other words, the compression fracture energy can be considered as the material property. These concepts have been applied to RC deep beams which fail in shear compression failure mode, and it has been confirmed that the concept of the localization can be applied for RC deep beams.The compressive stress-strain relationship which is modified according to the element length to make the energy absorption constant, has been applied for the analysis of RC deep beams in the post-peak region. Then, it has been confirmed that the load-deformation behavior and the size effect of shear strength of RC deep beams can be predicted accurately. The validity has also been confirmed by the comparison with the experimental result.The above results have been summarized and published in Journal of JSCE, Transactions of JCI and also international conference, such as FRAMCOS-4. Less

当混凝土因压缩而失败时，失败不会在整个身体中发生，但仅集中在峰后区域的一部分混凝土中。通过压缩中的故障的定位，可以解释受压缩的结构混凝土中的大小效应的存在。在这项研究中，对混凝土的单轴压缩测试进行了横截面形状，高度和横截面宽度的比率是参数变化的比率，以定量阐明本地化效果。根据局部应变的测量结果，已经对局部能量受苦进行了定量评估。根据这一测量，已经澄清说，当高度和横截面宽度的比率在一定程度上增加时，该定位是混凝土的压缩故障发生的。而且，发现可以使用侧面L…可以评估定位长度（故障区域的长度）。此外，还发现可以将每单位失效区域的吸收能量（压缩断裂能）评估为混凝土压缩强度的功能。换句话说，压缩断裂能可以视为材料特性。这些概念已应用于剪切压缩故障模式下失败的RC深束，并且已经确认可以将定位概念应用于RC深束。压缩应力应变关系根据元素的长度进行了修改以使能量遭受的持续变化，以使能量遭受的恒定，已应用于后峰后台面区域的RC深束。然后，已经证实，可以准确预测RC深梁的载荷形式行为和剪切强度的尺寸效应。与实验结果的比较也证实了有效性。上述结果已汇总并发表在JSCE杂志，JCI的交易以及国际会议（例如FRAMCOS-4）中。较少的