| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 91 === The research is to simulate the micro-macroscopic act of the forced steel unit under the fire. Macroscopic act including temperature effect, stress effect, once again fire effect. Microscopic act including analysis of a cross-section and scanning electron microscope analysis of a cross-section. The variables is in accordance with temperature and stress of the steel unit. The strain to divide into five parts: 0.6 Fy, 0.8 Fy, 1.0 Fy, 1.05 Fy and 1.10 Fy. The temperature to divide into six parts: 250℃, 300℃, 350℃, 400℃, 450℃ and 500℃. And the ways of the experiment including continued heating and circulate heating.
The results show that the temperature brings the steel material producing strain remain in low stress and higher temperature. But the strain brings the steel material producing strain remain in high stress and lower temperature. Must be avoid producing high stress at engineering design. In the same time, circulate heating make the creep of the steel material to raise when the temperature above 400℃. It is easy to break at 450℃ ~ 500℃. And increasing the circulate times, the steel material will be broken. The temperature variable is under 500℃, there is a blue oxidize membrane at the steel material a cross-section, and all of the steel material fractured mode is the dimple rupture, tradition fractured mode.
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