火害中建築用鋼筋材料機械性質變化之研究

台灣的環境地狹人稠，當火害發生時，極易造成嚴重的人命與財產損失，為減少火害帶來的傷害，需要有多方面的相關研究，然而至今與火害相關之結構鋼材研究均集中在火害發生前、後，至於火害延燒當中結構用鋼筋材料機械性質之研究，則付諸闕如；本研究以Gleeble高溫拉力試驗，模擬火場發生時之燃燒溫度與延燒時間，探討建築物結構用鋼筋材料在類似的延燒條件下高溫強度與斷面縮率之變化，實驗結果證實火場溫度提高，鋼筋材料之強度明顯下降，且火場溫度的高低對於鋼材強度之影響遠大於火害延燒時間的長短；此外，若火場溫度高於400℃則鋼筋材料之強度迅速降低，為維持鋼筋材料在建築物中結構性能，必須施以適當被覆隔熱，避免火害中鋼筋材料超過此溫度。

關鍵字

火害中；鋼筋材料；機械性質；強度

並列摘要

The study of fire accidents and their resulting damage should be given more attention in Taiwan because of increasing population. Previous studies on constructional steel bars related to fire damage has mostly concentrated on their compositional properties prior to or after firing. A study of their mechanical properties during firing is still lacking. A Gleeble hot tensile test machine was used to test the bars under different temperatures and time. After a series of hot tensile tests, it was concluded that the higher the firing temperature is, the more the tensile strength decrease. The effect of firing temperature on tensile strength is much more evident than the influence of firing time. If the firing temperature reaches 400￠J, the strength of the steel is quickly reduced. In order to enhance the constructional-related properties of bars in buildings, suitable coatings on steel bars to prevent materials from breaking under high temperatures are necessary.