箱型鋼柱填充鋼筋混凝土之耐火性能

Abstract

本研究旨在探討受軸向定載之箱型鋼柱填充鋼筋混凝土的耐火性能，參考耐火試驗法相關規定進行實驗。試體共計5支，參數為斷面大小及施加載重比。實驗結果顯示：斷面尺寸對於試體耐火性能時間的影響並不明顯，但斷面尺寸較大之試體，其熱膨脹伸長變形量會較小；載重比對於試體的耐火性能時間及熱膨脹伸長變形量皆有顯著的影響，小載重比之試體具有較佳之耐火性能時間且其熱膨脹伸長變形量亦會較大。此外，本研究之箱型鋼柱填充鋼筋混凝土試體試驗結果與文獻之箱型鋼柱填充混凝土試體進行比較，探討配筋與否及鋼骨比於試體耐火性能之影響。結果顯示，配置鋼筋能有效增加試體的耐火性能時間；鋼骨比對於高鋼筋混凝土承載比試體之耐火性能時間並無太大影響，但增加鋼骨比對於低鋼筋混凝土承載比試體之耐火性能時間有些微的助益。

This study aims to investigate experimentally the fire resistance of steel box columns filled with reinforced concrete subjected to a constant axial compressive load. Method of fire resistance test for structural parts of building was followed to conduct the test. A total of five specimens had parameters of the size of the cross section and load ratio. The test results had demonstrated that the size of the cross section had insignificant effect on the fire resistance. However, larger cross section of the specimen resulted in smaller axial elongation due to thermal expansion. Moreover, the load ratio had significant effect on both the fire resistance and axial elongation. Specimens subjected to smaller load ratio led to better fire resistance and larger axial elongation. Besides, in order to study the effect of the reinforced bars and the steel ratio, the results of these specimens were compared with those of steel box columns filled with plain concrete in the literature. The comparisons indicated that the reinforced bars effectively increased the fire resistance. The steel ratio had little influence on the fire resistance for specimens with high ratio of the axial capacity of the reinforced concrete to that of the column (RC capacity ratio). Nevertheless, increasing the steel ratio marginally increased the fire resistance for specimens with low RC capacity ratio.