火害模擬對鋼筋混凝土構件強度變化之探討

Simulation of Fire Damage on Reinforce Concrete Column Specimens

10.29847/JNUU.201012.0012

古運宏(Y. H. Guu)；張介人(Chieh-Jen Chang)；吳宗翰(Zone-Han Wu)；李增欽(Tzen-Chin Lee)

火害 ； 混凝土圓柱試體 ； 鋼筋 ； 應變能密度 ； 超音波脈衝波速 ； fire damage ； cylindrical concrete specimen ； steel bar ； strain energy density ； Ultrasonic Pulse Velocity

聯大學報

7卷2期（2010 / 12 / 01）

265 - 278

繁體中文

鋼筋混凝土建築物遭火害時，重則可能造成全面崩塌，輕則可能會使結構物強度受損，影響災後使用之安全。前人對有關火害升溫而造成鋼筋降伏強度之折減，已有甚多研究成果，本文則針對火害後鋼筋與混凝土強度之減損進行探討，首先將裸鋼筋與混凝土圓柱試體進行火害模擬試驗，並嘗試以應變能密度變化之理論探討其火害損傷。其次再灌鑄鋼筋混凝土柱構件進行高溫爐之火害模擬試驗，藉此針對火害對構件內鋼筋降伏強度之折減現象進行探討，同時亦以應變能密度變化為損傷參數(Damage Variable)，而予以分析評估火災高溫對鋼筋強度所造成的損傷，經試驗結果顯示：鋼筋於火害冷卻後其降伏強度之損傷，與應變能密度之減損均不大，但對混凝土抗壓強度與應變能密度之減損則頗鉅，並隨火害溫度之上升而急遽下降，其損傷遠大於鋼筋。

Reinforce concrete building under fire combustion may seriously induced total collapse or survive in structural damage. Thus the fire combustion may influence the safe of building structure. There are many research reports on the reduction of steel yielding stress by fire damage. This study aimed at the strength damage of steel bar with concrete protection under the fire combustion. Firstly, we simulated by fire heating #4 steel bars and the cylindrical concrete specimens in electrical oven. Then the strength test, stress-strain measurement, and strain energy density analysis of the fired specimens were investigated. In addition, the variation of wave velocity by ultrasonic pulse velocity instrument was measured, and the fire damage was analyzed. Secondary, the reinforce concrete-cylinder column specimens were molded for fire heating in big electrical oven, and the fire damage was evaluated with the same method. The experimental test results revealed that the steel bars were damaged slightly when fire combustion ceased and the bars were air cooled to atmospheric temperature. But the concrete specimens were damaged seriously, and fire temperature increased the damage promptly.

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