|Budget Amount *help
¥3,100,000 (Direct Cost : ¥3,100,000)
Fiscal Year 1998 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1997 : ¥2,400,000 (Direct Cost : ¥2,400,000)
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.