权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Control of Thermal Cracking in Mass Concrete

大体积混凝土热裂的控制

基本信息

批准号：
61302057
负责人：
NAGATAKI Shigeyoshi
金额：
$ 3.78万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Co-operative Research (A)
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/grant/KAKENHI-PROJECT-61302057/
关键词：
Mass Concrete Thermal Cracking Heat of Hydration Rate of Heat Hydration Adiabatic Temperature Rise Bond Creep Compressive Creep Tensile Creep, Bond Stress Acoustic Emission 引張クリープ AE(アコースティックエミッション)応力拡大係数断熱温度上昇付着応力

项目摘要

In this year, prediction of adiabatic temperature rise as a result of cement hydration was attempted. In addition, properties of tensile creep in concrete and bond creep in reinforced concrete member at early age were also studied. The summary of this study is as follow.(1) To predict adiabatic temperature rise induced by heat of cement hydration,an experimental equation based on the rate of heat induced by cement hydration is obtained as a function of curing temperature. The rate of heat of heat generated at any instant and at any curing temperature can thus be calculated by using the above equation. Heat of cement hydration under adiabatic condition can also be calculated by integrating the above equation. The adiabatic temperature is then calculated from the above heat of cement hyfration. The results obtained from the above is then finally compared with its corresponding experimental results. It is found that the accuracy of the experiment has a signfificant effect on thesee result … More s. By taking the consideration of this effect into the proposed method, the adiabatic temperature can be accurately predicted.(2) To understand the mechanism of thermal stress, tensile creep property of concrete subjected to compressive stress history is studied. The redults show that the tensile creep of concrete subjected to compressive stress history is greater than that of concrete without subjected to compressive stress history. In addition, based on the acoustic emission measurement, part of this tensile creep is found to be induced by the deformation of concrete due to the micro crack.(3) To establish an effective way of predicting the thermal crack width, the bond creep of reinforced concrete members at the early age under drying shrinkage condition was analyzed. The analytical results showed good agreement with the experimental results. The bond strength and the bond creep as well as the bond slip can be quantitatively predicted by the proposed method.(4) A finite element approach was used to analyze the development of thermal crack by taking the consideration of the position of reinforcement, Results show that it is possible to calculate the induced displacement and thermal stress near cracking tip. Thus, the development of thermal cracking can be rather accurately monitored by using the above approach. Less

这一年，人们试图预测水泥水化导致的绝热温升。此外，还研究了混凝土的拉伸徐变性能和钢筋混凝土构件早期的粘结徐变性能。(1)为了预测水泥水化热的绝热温升，建立了水泥水化热速率随养护温度变化的经验公式。因此，可以使用上述公式计算在任何时刻和任何固化温度下产生的热的速率。通过对上述方程的积分，还可以计算绝热条件下水泥的水化热。绝热温度然后由上述水泥的水化热计算出来。最后将得到的结果与相应的实验结果进行了比较。结果表明，实验的准确性对…结果有显著的影响为了更好地理解温度应力产生的机理，研究了混凝土在压应力历史作用下的拉伸徐变特性。结果表明，有压应力历史的混凝土的徐变大于无压应力历史的混凝土的徐变。此外，通过声发射测试发现，混凝土的拉伸徐变部分是由混凝土微裂缝引起的变形引起的。(3)为了建立一种有效的预测温度裂缝宽度的方法，分析了干燥收缩条件下钢筋混凝土构件早期粘结徐变。分析结果与实验结果吻合较好。该方法可以定量预测粘结强度、粘结蠕变和粘结滑移。(4)考虑钢筋位置的影响，采用有限元方法对热裂纹的发展进行了分析，结果表明可以计算裂纹尖端附近的诱导位移和温度应力。因此，使用上述方法可以比较准确地监测热裂纹的发展。较少