建築物受火害時，柱、梁、版等構件會因高溫產生變形，其中以柱的變形最為重要，本研究旨在探討鋼筋混凝土柱在火害升溫與降溫段之熱變形分析與預測；利用ISO 834標準升溫曲線、Eurocode 1降溫曲線模擬升降溫過程，使用ANSYS程式六面體的Solid 5元素分析熱-結構耦合問題，過程中考慮混凝土升溫剝落以及降溫劣化等現象，模擬實驗試體在升溫與降溫過程中鋼筋混凝土柱的行為。
分析過程中，升溫段之材料組合律使用高溫中混凝土暫態彈性係數、修正後的升溫段之熱膨脹係數，在模擬過程中，使用ANSYS Element Birth and Death功能將大於500℃的混凝土去除，探討混凝土在高溫剝落對柱試體軸向變形造成的影響；降溫段使用高溫中混凝土穩態彈性係數、修正後降溫段之熱膨脹係數，本研究將降溫時混凝土的應變分為自由熱應變（ε_th）、暫態潛應變（ε_tr）以及瞬態應力相關應變（ε_σ），以考慮自由熱應變、暫態潛應變受熱後所產生的不可逆變化，以外，再配合本研究提出的兩個降溫模型及處理流程，用以預測降溫時柱的軸向變形。
預測結果顯示，升溫段中加入剝落模擬的鋼筋混凝土柱模型之軸向變形預測趨勢和實測值非常接近。在降溫段中，本研究發現軸向位移在升溫之末、降溫之初變化非常快速，會在降溫末期達到最大值，因此，柱在升溫過程或最高溫時沒有發生破壞不能代表降溫過程中就不會發生破壞，此與救災人員在火災發生時進入火場之安全性有關，火害後建築物的危險評估也應考慮此特性。

The behavior of RC columns in fire is determined by temperature directly. With ISO 834 curve and Eurocode decay rate, we can simulate the heating and cooling stages of RC columns by using regular hexahedron element as known as “Solid 5” in ANSYS. Consider Axial deformation of RC columns with concrete cover spalling at heating and irreversible strain at cooling stage, we can study the deformation of RC columns during fire precisely.
By use of Eurocode defined transient-state elastic modulus of concrete to simulated the constitutive equation of concrete at heating stage. “Element birth and Death” was input to found and “killed” the element which was heated over 500℃ in ANSYS to simulated “the spalling” of concrete. Also, using Eurocode defined steady-state elastic modulus of concrete to simulated the constitutive equation of concrete at cooling stage, due to irreversible crack, duo-cooling model were took thermal strain(ε_th), instantaneous stress-related strain(ε_σ) and transient creep strain(ε_tr) into consider separately.
At present, the prediction of axial deformation of RC columns during heating stage has been quite accurate after “the spalling” of concrete cover was simulated. We are discovered axial displacement of RC columns have significant decay at the initial stage of cooling, also the maximum variation of axial displacement was reached at the end of cooling stage. Over all, the predictions of axial deformation of fire damaged columns are quite accurate to the test.

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