| 種別 | paper |
| 主題 | Constitutive Equation and Yield Condition of Concrete Loaded at Early Age |
| 副題 | |
| 筆頭著者 | Monoj Kanti DAS（Graduate School of Yokohama National University） |
| 連名者1 | Tatsuya TSUBAKI（Yokohama National University） |
| 連名者2 | |
| 連名者3 | |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 14 |
| 号 | 2 |
| 先頭ページ | 1017 |
| 末尾ページ | 1022 |
| 年度 | 1992 |
| 要旨 | INTRODUCTION Hardened concrete properties are already well investigated. A great amount of concrete research has, to a great extent, been devoted to the properties of the fresh concrete as well. On the contrary, the intermediate stage, when the newly placed concrete has just started to solidify and a certain strength can be developed, has not been examined thoroughly. Concrete is, however, very often exposed to loads at very early ages in the construction processes. Therefore, it is important to investigate the mechanical properties of concrete at early ages. For early age concrete, age or time is one major factor. Time may be, however, definitely not the best parameter when trying to define early age. It is probably more correct to define early age by a degree of hydration or a level to which some property such as strength has developed. In the present study, a material model is proposed in aim to express the behavior of concrete in the early stage. In the early stage, the behavior of concrete is rather viscous than elastic. Therefore, for the case of material modeling, the viscous as well as elastic effect is to be taken into consideration for a lower stress level. At a higher stress level, the young concrete gradually approaches to a yield value, after which the plastic property comes into effect along with the viscous effect. To accomodate that yielding behavior, a yield criterion must be set up. Therefore, the total behavior of the young concrete consists of three parts. Two (elastic and viscous) parts are active below a threshold value and all the three (elastic, viscous and plastic) parts are to be included above the threshold in the formation of the constitutive matrix. In the following text, the constitutive law and a yield condition applicable to express continuously the behaviors of both viscoelastic and viscoplastic states are proposed. In this analysis, concrete is considered homogeneous. CONCLUSIONS A constitutive relationship for early age concrete is modeled as a combination of viscoelastic and plastic material models. The age-dependence of the material constants are taken into account. Through the numerical simulation for an imposed strain history, the appropriateness of the present model is checked. The effect of other relevant parameters such as temperature and mix proportions can also be taken into consideration in this model. |
| PDFファイル名 | 014-01-2176.pdf |