STRUCTURAL PERFORMANCE OF FIBER-REINFORCED CONCRETE APPLIED TO CES MEMBERS
1. Introduction Concrete-encased steel (CES) structural system consisting of fiber-reinforced concrete (FRC) and encased steels is a new composite structural system. Continuous and comprehensive studies are currently being conducted to make this system practical. In existing studies, the ultimate st...
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Veröffentlicht in: | Journal of Structural and Construction Engineering (Transactions of AIJ) 2016, Vol.81(729), pp.1945-1953 |
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Format: | Artikel |
Sprache: | eng ; jpn |
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Zusammenfassung: | 1. Introduction Concrete-encased steel (CES) structural system consisting of fiber-reinforced concrete (FRC) and encased steels is a new composite structural system. Continuous and comprehensive studies are currently being conducted to make this system practical. In existing studies, the ultimate strength of CES columns were calculated using the strength superposition method based on test results. However, for CES columns in which FRC is used, the contribution of the confinement effect to the structural performance remains unclear. This study discusses the evaluation of the strength and confinement effect of FRC based on test results. 2. Investigation of the crack strength of FRC and CES members Material tests on FRC were conducted. Results clarified that the crack strength of cover FRC was the same as that of normal concrete. The crack strength of CES members can be calculated using the existing evaluation formula of RC members. 3. Investigation of the bending strength of FRC Eccentric compression tests on FRC short columns were conducted. Selected test parameters were eccentric distance (axial load ratio) and loading directions (uniaxial or biaxial). Using the AIJ-SRC formula, the ultimate flexural strengths of all specimens were found to be at least 1.0 times that of design ultimate strengths. The application scope of this formula is for encased reinforced concrete and not for encased FRC in this study. Thus, the current AIJ-SRC formula can be conservatively used for FRC. The accuracy of fiber analysis was verified by comparing with test results. 4. Investigation of the local buckling reinforcement by FRC Seven columns were tested under axial compression loading to investigate the effects of width-to-thickness ratio and synergistic interaction between cover FRC and encased steel. Selected test parameters were composite or non-composite columns (steel, FRC, and CES) and width-to-thickness ratio of encased steel. Increase in steel strength by buckling due to confinement can be expected for cover FRC. Based on test results, AIJ design formulas for SRC structures can be applied to evaluate the ultimate strengths of CES columns with large width-to-thickness ratios. 5. Conclusion The evaluation method of the structural performance of the CES structure was investigated. Main findings are summarized as follows. 1) Crack strength and bending strength of FRC applied to the CES structure are equivalent to those of normal concrete. However, the toughness of FRC imp |
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ISSN: | 1340-4202 1881-8153 |
DOI: | 10.3130/aijs.81.1945 |