本研究假設鋼構斷面受火後溫度均勻分佈、一維熱傳導及防火被覆表面受標準升溫加熱，進而推導鋼構防火被覆後之溫度微分方程，並利用數值解製成設計圖表，提供設計者參考。利用有限元素法和有限差分法驗證推導時所假設之差異性，驗證結果顯示，鋼構在厚度方向假設溫度均勻分佈是合理的，但二維分析結果顯示，鋼構斷面溫度分佈並不均勻，亦即假設一維熱傳導分析無法實際反應溫度之分佈，但二維分析結果顯示，其溫度小於一維分析結果，亦即，利用一維推導出之鋼構溫度微分方程，所設計出之防火被覆厚度是保守的。

In this study, the temperature differential equation of steel with fireproof coating is derived by assumption of steel section with no temperature gradients under fire condition of one-dimensional heat conduction when the steel surface is heated by the uniform fire temperature. The chart and table are made to provide design rules. By using one and two-dimensional finite element analysis to confirm the differences of above assumption, one-dimensional analysis results show that the temperature distribution in the cross-section of steel is reasonable while two-dimensional analysis shows that the temperature distribution in steel section is not evenly spread. That is,one-dimensional assumption couldn’t be actually applied or response to heat conduction analysis while the two-dimensional analysis shows its temperature is less than one-dimensional analysis. Hence, the design thickness of fireproof coating in steel is conservative when using one-dimensional temperature differential equation.