火害後鋼筋混凝土樑極限強度分析

Ultimate Strength Analysis for a Concrete Beam after a Sustained Building Fire

林誠興(C. S. Lin) ； 王士承(S. C. Wang) ； 周國達(K. D. Chou) ； 陳德啟(T. C. Chen)

《南亞學報》 30期 (2010/12) Pp. 59-82

https://doi.org/10.6989/JN.201012.0059

摘要

建築物主要是由樑、柱、板等構件所組成，當建築物發生火災時，建築物的結構強度可能會因高溫而衰減。因此分析建築結構受火害後是否還保有原本的設計強度，以及哪些地方需要做結構補強，必須要有更精確的工程方法來探討。隨著電腦科技、CFD（Computational Fluid Dynamics）軟體、火災數值模型的持續發展，數值模擬方法已廣泛應用到防火工程研究。本文以FDS（Fire Dynamics SiMulator）火災模擬軟體建構建築物火災熱流場數值模型，探討不同火勢大小、樑位置對空間熱流場溫度變化之影響，並截取樑邊界溫度隨時間之變化，以PHOENICS熱流模擬軟體詳細計算鋼筋混凝土樑受火害時內部溫度分佈，最後以工程方法計算樑強度之量化數據供參考。

關鍵字

火災 ； 鋼筋混凝土樑 ； 數值模擬 ； 場模式

並列摘要

More than 90% of the buildings in Taiwan use reinforced concrete (RC) structures. After fire damage, whether the RC structure can still be safe or not is important to human's life and property. However, obtaining fire thermal parameters quantitative data from actual building fires is impossible. Therefore, numerical siMulation software that siMulates fire scenarios has been utilized to model fires for fire protection engineering. Beam strength decreased due to high temperature. To obtain beam precise temperature profile in a building fire, this study utilizes fire model FDS and field model PHOENICS software to siMulate fire development and beam inner temperature variation. Fire scenarios and beam surface temperatures in a room fire were analysed by FDS fire model. Beam boundary temperatures will be transferred into PHOENICS field model to compute the detailed temperature profile within the beam. The structural strength estimated using beam various cross-section temperature to investigate dynamic ultimate bending moment of a RC beam in a room fire. Through the various siMulations and calculations, this investigation obtains the influence of different beam positions, fire intensity, fire duration and fire damage sustained (whether two or three faces) by a RC beam after a building fire.

並列關鍵字

fire ； reinforced concrete beam ； numerical siMulation ； field model ； FDS