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研究了采用防火板保护钢柱四面受火时的截面温度计算方法,分别考虑了防火板与钢柱无间隙及防火板与钢柱有间隙两种情况。由于采用防火板保护时,钢构件与防火保护层内表面之间主要通过热辐射进行热量传递,与现行欧洲规范(EC 3)公式假定构件防火保护层之间通过热传导进行热量传递不同。现行EC 3规范公式能较为准确地计算热传导系数较小的防火涂料保护时构件升温,但不能准确计算火灾下热传导系数较大的防火薄型板保护钢柱的温度。通过在现行规范公式中增加空气的热阻一项,以考虑热辐射传热方式对构件截面升温的影响。分别采用有限元方法和建议公式,对防火薄型板保护,不同保护层厚度和不同截面系数钢柱截面升温规律进行分析,结果表明修正公式的计算结果与有限元结果吻合良好。
The method of calculating the cross-section temperature of steel columns with fire panels is studied. There are two cases of gap between fire panels and steel columns, and the gap between fire panels and steel columns respectively. Due to the protection of the fire board, the heat transfer between the steel components and the inner surface of the fire protection layer mainly by heat radiation is different from the current European standard (EC 3) formula assuming heat transfer between the fire protection layers of the components by heat conduction. The current EC 3 specification formula can accurately calculate the components with small thermal conductivity when the protection of fire protection components, but can not accurately calculate the fire under the fire conductivity of large thin-plate fire protection steel column temperature. By adding one of the thermal resistances of air to the existing standard formula to consider the influence of radiant heat transfer on the temperature rise of the cross section of the component. The finite element method and the recommended formula were respectively used to analyze the law of the protection of the fireproof thin plate, the thickness of the protective layer and the steel column cross section with different cross section coefficients. The results show that the calculation results of the correction formula are in good agreement with the finite element results.