鋼筋混凝土樑受火害後之剪力強度數值模擬

Numerical Modeling of the Shear Strength for Reinforced Concrete Beams after Fire Damage

鋼筋混凝土建築在遭受嚴重火害後是否還能使用，必須對其結構體之安全性進行評估，評估的結果對人們生命與財產的權益影響甚鉅，因此必須發展出一套經濟有效的分析模式以判定鋼筋混凝土建築在火害後繼續使用的可能性。由於結構體之安全性與各桿件之行為有密切之關係，因此欲評估火害後結構體之安全性，必須先行了解鋼筋混凝土桿件在火害後之性質。建築物在發生火災後，由於桿件內各位置承受不同之溫度，鋼筋及混凝土材料之力學性質均會有相當大之改變，因此評估起來變得非常複雜。本研究先以有限差分法(Finite Different Method)模擬樑斷面受火害後之溫度分佈，再將斷面分割為M×N個單元，每一單元內視其為等溫、等性質，以塊狀系統法(Lumped System Method)，分別計算鋼筋及混凝土材料受火害後之溫度折減，再以ACI規範之觀念，模擬計算火害後鋼筋混凝土樑之剪力強度。兩種模擬結果分別與相關文獻及實尺寸火害實驗驗證相當符合。本研究之結果將有助於往後對火害後結構體安全評估之參考。

After fire damage, whether the reinforced concrete structure can still be safe or not is very important to human's life. When structures were exposed to fire, the different temperature distributions in the cross-section elements changed the reinforced bars and concrete to have different mechanical properties. The analysis of reinforced concrete structure after fire damage becomes complicated. This investigation is based on the assumptions in the ACI Code, and use the Finite Difference and Lumped System Method, to calculate the shear strength of reinforced concrete beams after fire damage. The results are consistent with the actual full-scale fire experiments.