The reduction behaviors and characteristics of products of the Fe-Cr-O system (FeCr2O4 and Fe2O3+Cr2O3) and Fe-Cr-Ni-O system (Fe2O3+Cr2O3+NiO) under various conditions were studied. The results show that more ...The reduction behaviors and characteristics of products of the Fe-Cr-O system (FeCr2O4 and Fe2O3+Cr2O3) and Fe-Cr-Ni-O system (Fe2O3+Cr2O3+NiO) under various conditions were studied. The results show that more Fe-Cr or Fe-Cr-Ni solution and less residual carbon content were obtained at higher temperatures and lower initial molar ratio of C to O (nC:nO). The degree of reduction was highly dependent on both time and temperature, and the residual carbon content greatly increased with increasing nC:nO at each temperature. The products generated during the carbothermic reduction of the Fe-Cr-O system were examined using X-ray diffraction (XRD). A scanning electron microscope (SEM) coupled with energy dispersive spectrometer was used to observe the microstructure and the distribution of elements in the various phases of the final reduction products of the Fe-Cr-O and Fe-Cr-Ni-O.展开更多
In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, doe...In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, does not provide full interaction of a steel beam and a concrete slab. This changes strain distribution in cross-sections of a composite girder and results in redistribution of internal forces in steel and concrete element. In the paper partial interaction index defined on the basis of a neutral axis position, which can be used for verification of steel-concrete interaction in real bridge structures rather than in specimens is proposed. The range of the index value changes, obtained during load testing of a typical steel-concrete composite beam bridge, is presented. The investigation was carried out on a motorway viaduct, consisting of two parallel structures. During the testing values of strains in girders under static and quasi-static loads were measured. The readings from the gauges were used to determine the index, characterizing composite action of the girders. Results of bridge testing under movable load, changing position along the bridge span is presented and obtained in-situ influence functions of strains and index values are commented in the paper.展开更多
基金Project (51074025) supported by the National Natural Science Foundation of ChinaProject (FRF-SD-12-009A) supported by the Fundamental Research Funds for the Central Universities,China
文摘The reduction behaviors and characteristics of products of the Fe-Cr-O system (FeCr2O4 and Fe2O3+Cr2O3) and Fe-Cr-Ni-O system (Fe2O3+Cr2O3+NiO) under various conditions were studied. The results show that more Fe-Cr or Fe-Cr-Ni solution and less residual carbon content were obtained at higher temperatures and lower initial molar ratio of C to O (nC:nO). The degree of reduction was highly dependent on both time and temperature, and the residual carbon content greatly increased with increasing nC:nO at each temperature. The products generated during the carbothermic reduction of the Fe-Cr-O system were examined using X-ray diffraction (XRD). A scanning electron microscope (SEM) coupled with energy dispersive spectrometer was used to observe the microstructure and the distribution of elements in the various phases of the final reduction products of the Fe-Cr-O and Fe-Cr-Ni-O.
文摘In the case of composite girders, an effective cooperation of both parts of the section is influenced by deformability of connectors. Limited flexural stiffness of welded studs, used commonly in bridge structures, does not provide full interaction of a steel beam and a concrete slab. This changes strain distribution in cross-sections of a composite girder and results in redistribution of internal forces in steel and concrete element. In the paper partial interaction index defined on the basis of a neutral axis position, which can be used for verification of steel-concrete interaction in real bridge structures rather than in specimens is proposed. The range of the index value changes, obtained during load testing of a typical steel-concrete composite beam bridge, is presented. The investigation was carried out on a motorway viaduct, consisting of two parallel structures. During the testing values of strains in girders under static and quasi-static loads were measured. The readings from the gauges were used to determine the index, characterizing composite action of the girders. Results of bridge testing under movable load, changing position along the bridge span is presented and obtained in-situ influence functions of strains and index values are commented in the paper.