| 種別 | paper |
| 主題 | Grip Effect on Failure Mode and Strength of FRP Rods |
| 副題 | |
| 筆頭著者 | Hosam Hodhod（Tokyu Construction） |
| 連名者1 | Taketo Uomoto（University of Tokyo） |
| 連名者2 | |
| 連名者3 | |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 15 |
| 号 | 1 |
| 先頭ページ | 1247 |
| 末尾ページ | 1252 |
| 年度 | 1993 |
| 要旨 | INTRODUCTION FRP tension elements are promising candidates for the future reinforcement of concrete; where lighter, stronger and more durable materials with good magnetic properties are needed. However, the customization of applying FRP as concrete reinforcement needs more understanding of their behavior that, consequently, leads to more reliable application. The FRP rods have shown several phenomena that need interpretation. One of these is the variation of uniaxially reinforced FRP rods tensile strength versus fiber content (volume fraction Vf). The rods of three different materials do not show consistent strength increase with fiber content: where the high fiber contents give strength values less than expected. In this research, the causes of this phenomenon are investigated. The approach depends on correlating the strength value and failure mode and studying the effect of the gripping system on the stress distribution inside the rod. First, the failure modes of the tested rods are categorized. Then, a reference failure mode under pure uniaxial tension is obtained experimentally. The effect of the used gripping system on the stresses is determined analytically. Comparing the failure modes in actual conditions with reference mode and in view of stress distributions, the goveming failure mode at each fiber content is determined. It should be understood that quantitative description of failure propagation inside the rod is not the target of this research, since the failure criteria like inter-laminar and cross-laminar shear strength are not available for the studied materials. Therefore, a qualitative description of the possible failure modes (in view of the resulting stress fields) is suggested and supported by the experimental observations on the studied materials and similar occurrence of such modes as found in the literature. CONCLUSIONS The tensile strength variation of unidirectionally reinforced FRP rods versus fiber volume fraction, is studied for three different materials. The approach for clarifying the phenomena observed depends on the correlation between the strength and failure mode. The failure modes were characterized for the tested specimens and the ideal failure modes and strength values, under pure axial tension, were determined experimentally. He ideal behavior was found independent of the fiber content, unlike the practical cases. The effect of lateral grips on the state of stress inside the rod was determined analytically and the possible modifications of the failure modes were found to be through shear failure modes. Correlation between these concluded modifications and the experimental observations was successful. The effect of the grips on reducing the strength FRP rods, with unidirectiona11y aligned fibers, is found to be serious for the cases of high fiber content, specially for CFRP. From the manufacturer side, the efficiency of the rods can be increased by utilizing different matrix that provide higher inter-1aminar shear strength for AFRP and GFRP. For CFRP, however, the source of inefficiency is the cross-1aminar shear strength that is dependent on the fiber not the matrix. Therefore, replacement of the current gripping system by less aggressive one is the way to efficient utilization of the rods. A proposal for reducing grips lateral pressure, and consequently strength loss, is suggested based on changing the taper angle of the grips and is explained in reference. |
| PDFファイル名 | 015-01-1212.pdf |