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

Evaluation of Fracture Properties of Various Concretes

各种混凝土断裂性能评价

基本信息

批准号：
09650508
负责人：
NIWA Junichiro
金额：
$ 1.98万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY (1998)Nagoya University (1997)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650508/
关键词：
High Strength Concrete Self-Compacting Concrete Fracture Mechanics Fracture Energy Tension Softening Curve Fictitious Crack J Integral Size Effect 仮想ひび割れ幅

项目摘要

As the first step of this research work, fracture properties of various concretes, such as high strength concrete, self-compacting high performance concrete, etc. have been evaluated based on the fracture mechanics of concrete. Self-compacting high performance concrete is a very promising new concrete because it does not need the compaction during casting. However, from the viewpoint of the fracture mechanics, it is found that it will provide less fracture energy compared with conventional concrete because the amount of coarse aggregates included in self-compacting high performance concrete is remarkably reduced to provide the sufficient flowability. On the other hand, the fracture energy of high strength concrete shows the same tendency as conventional concrete because the content of coarse aggregates in high strength concrete is not significantly different from conventional concrete.As the second step, the experimental method to determine the tension softening curve of concrete has been investigated extensively. The tension softening curve is one of the most important parameters for the fracture mechanics of concrete. In this research, the new method to determine the tension softening curve of concrete has been proposed. In this new method, the release of elastic strain energy is taken into account. Moreover, the extension of the fictitious crack can be evaluated accurately based on the measurement for longitudinal strain distribution. Although this new method is quite simple compared with inverse analysis, it can predict the tension softening curve of concrete with reasonable accuracy.Finally, the size effect of structural concrete using various concretes is numerically predicted based on the obtained fracture properties.

作为本研究工作的第一步，基于混凝土断裂力学，对各种混凝土，如高强混凝土、自密实高性能混凝土等的断裂性能进行了评价。自密实高性能混凝土是一种很有前途的新型混凝土，它不需要在浇筑过程中进行压实。然而，从断裂力学的观点来看，它将提供更少的断裂能与传统的混凝土相比，因为包括在自密实高性能混凝土中的粗骨料的量显着减少，以提供足够的流动性。另一方面，由于高强混凝土中粗骨料的含量与普通混凝土没有显著差异，高强混凝土的断裂能表现出与普通混凝土相同的趋势。混凝土的拉伸软化曲线是混凝土断裂力学的重要参数之一。提出了确定混凝土拉伸软化曲线的新方法。该方法考虑了弹性应变能的释放。此外，虚拟裂纹的扩展可以准确地评估基于纵向应变分布的测量。虽然这种新方法与反分析相比相当简单，但它能以合理的精度预测混凝土的拉伸软化曲线。最后，基于所得的断裂特性，对使用不同混凝土的结构混凝土的尺寸效应进行了数值预测。