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Development of Method Evaluating Damaged places and Levels in Concrete Structures Through AE Monitoring

通过声发射监测评估混凝土结构受损部位和程度的方法的开发

基本信息

批准号：
61850084
负责人：
SATAKE Masao
金额：
$ 3.33万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-61850084/
关键词：
acoustic emission concrete fracturing level deterioration sea water alkali-aggregate reaction Kaiser effect source location wave form analysis 凍結融解

项目摘要

The evaluation of hereditary stress through the kaiser effect was researched and the following results were clarified.(1) The accuracy in evaluating the hereditary stress depends on the loading velocity of hereditary stress at each loading level which is determined on the basis of the ultimate strength of concrete specimens, but except for the almost fractured state, the influence of loading velocity on the accuracy in evaluating it is small and the mean error is ablut 4percent.(2) The influence of mix proportion on the accuracy in evaluating the hereditary stress is small.(3) The compressive and tensile stresses in alternately loaded plain concrete beams which are 15cm high, 15cm wide and 53cm long are evaluated through the cores cut out of them, and their errors are about 18 percent and 9.5 percent in average reespectively.Defining the parameter m which expressed the increasing rate of logarithmic value of AE cumulative event count to unit inelastic axial strain, the damege levels of concrete specimens were evaluated and the following results were obtained.(1) The m values have good correlation with the ultimate strength of concrete specimens and this relationship between them is approximately linear.(2) The m values of concrete specimens damaged by the freezing and thawing action or repeated load are linearly correlated with various deterioration levels.The AE method was applied to the early identification of alkali-aggregate reaction, and the following results were concluded.(1) The maximum values of AE event rate in mortar specimens including reactive aggregate arise in 10 days and their values are extremely large in comparison with tghe ones composed of non-reactive aggregate.(2) The increase of specimen length are linearly correlated with AE coumulative event count. In addition to the above, the accuracy of three-dimensional AE source location was improved.

研究了用凯泽效应评价遗传胁迫，并阐明了以下结果。(1)遗传应力的估算精度取决于各加载水平下遗传应力的加载速度，而加载速度是根据混凝土试件的极限强度确定的，但除几乎断裂状态外，加载速度对遗传应力估算精度的影响很小，平均误差约为4%。(2)配合比对遗传应力评定精度的影响较小。(3)通过对高15 cm、宽15 cm、长53 cm的素混凝土梁在交变荷载作用下剪芯测得的压应力和拉应力，其平均误差分别为18%和9.5%，并定义了表征声发射累积事件数对数值对单位非弹性轴向应变的增长率的参数m，对混凝土试样的损坏程度进行了评估，并获得了以下结果。(1)m值与混凝土试件的极限强度有很好的相关性，两者之间近似呈线性关系。(2)混凝土试件在冻融作用或反复荷载作用下的m值与不同的劣化程度呈线性相关。(1)含活性骨料砂浆试件的AE事件发生率在10 d内出现最大值，与非活性骨料砂浆试件相比，其值非常大。(2)试件长度的增加与声发射累积事件数呈线性相关。此外，还提高了三维声发射源定位的精度。