| Summary: | 碩士 === 國立高雄應用科技大學 === 土木工程與防災科技研究所 === 98 === The fire-damaged building must be identified by using the effective method whether continuously to use or not. Although many researchers have studied on the mechanical property of the fire-damaged steel, few studies were carried on microstructural characterization. Thus, this study is focused on the relationship between mechanical behavior and microstructural characterization for the fire-damaged steel. Consequently, it will be helpful to the identification of the fire-damaged building for structural safety assessment. The conclusion is summarized as follows:
1.Based on the relation of fire-damaging temperature and mechanical property. The result indicated that the strength of the fire-damaged rebar at fire-damaging temperature treated lower than 600℃ is not remarkable reduction. When the temperature was up to 700℃, the strength (about 10% reduction) shows a marked tendency to decrease. The strength has above 15% reduction at 800℃, and the yield strength of the rebar has been unable to conform to the requirement of CNS 560 standard.
2.Based on the relation of fire-damaging temperature and microstructural characterization. The result showed that the structure of cementite existed in pearlite will transfer from coarse to spheroid at the increase of fire-damaging temperature. Then, the compact structure arrangement will change into the loose structure arrangement, owing to the precipitation of more ferrites. Thus, there is an evident relationship between microstuctural change and mechanical reduction for the fire-damaged rebar.
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