| 種別 | paper |
| 主題 | Size Effect for the Reinforcing Fibers of FRP Rods |
| 副題 | |
| 筆頭著者 | Hosam HODHOD（Graduate School of Tokyo University） |
| 連名者1 | Taketo UOMOTO（Tokyo 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 | 1 |
| 先頭ページ | 1155 |
| 末尾ページ | 1160 |
| 年度 | 1992 |
| 要旨 | INTRODUCTION FRP rods suffer some problems concerning the appropriate anchorage and the failure pattern. This affects their potential for practical application. The evaluation of rods optimum (theoretical) strength is, then, important from two points of view. First, it gives estimation to strength reduction due to improper anchorage. Second, it helps provide better understanding to the failure mechanism, through the comparison of the proposed theoretical mechanism (in calculation) and the experimental one. Recently, Monte Carlo simulation was applied for the evaluation of the optimum strength of the FRP rods. The fibers inside the rod section are given strengths at random, according to appropriate distribution, and the damage propagation across the section is studied till failure. For this purpose, a fibers strength distribution should be used. The existence of the matrix in the composite helps transfer the load of the broken fibers to the surrounding ones, across a certain transfer length, and back to the original fibers. Hence, the damaged fiber will be ineffective only along the transfer length where the damage accumulation takes place. Therefore, the relevant strength distribution for evaluating the composite is that obtained for the transfer length. The standard testing methods for the fibers specifies a certain gage length which is usually much bigger than the transfer length. As the size and length of the fibers affect their strength, a certain size effect rule should be employed for the extrapolation of the strength distribution from the standard one. A commonly used rule is that of Weibull distribution, based on the weakest link concept. This rule, however, was subjected to some criticism in case of the glass optical fibers. Therefore, in this research, the reliability of the rule is investigated for three kinds of fibers commonly used in practice for unidirectional reinforcement of FRP rods. CONCLUSIONS 1. For the three kinds of fibers tested in this research and for the two applied strain rates, Weibull modulus is a material constant in axial tension. 2. For the case of carbon fibers, the weakest link concept can be used for predicting the strength distributions of shorter fibers regardless of the strain rate. 3. In case of glass fibers, the weakest link concept is still applied but with strain rate dependence. 4. For aramid fibers, the size effect cannot be described by the weakest link concept that gives an overestimation to the strength although distribution shape is efficiently described. |
| PDFファイル名 | 014-01-1200.pdf |