Abstract: Based on analysis of the existing methods to estimate the thermal insulation performance of intumescent fire retardant coatings for steel structure, a concept of segment equivalent thermal resistance was presented, which could describe the relationship between thermal conductivity and expanded film thickness via the value of thermal resistance And based on the reaction character of the intumescent fire retardant coatings, the equivalent thermal resistance was divided into the pre-intumescent and post-intumescent stage. The method to calculate the segment equivalent thermal resistance was given. Standard fire tests were conducted on two types of fire retardant coatings for steel structure, showing that the temperature rising of the specimens had good accordance with the result simulated by the segment equivalent themal resistance. The segment equivalent thermal resistance could be a basis to evaluate the thermal insulation performance of different types of fire retardant coatings, to provide the referential data for the fire resistance design of steel structure, and to help analyze the mechanism of fire retardant coatings.

Key words: intumescent fire retardant coatings, steel structure, equivalent thermal resistance, segment

摘要： 在总结分析膨胀型防火涂料隔热性能评价方法的基础上，提出了分段等效热阻的概念，即用热阻值的大小综合反应涂料的导热系数和膨胀厚度的变化，根据膨胀型防火涂料的反应特点，将涂料的热阻分为膨胀前和膨胀后两个阶段分别进行计算，并提出了计算分段等效热阻的方法。 对２种型号的膨胀型防火涂料进行了标准条件实验，用分段等效热阻模拟的试件温升与实验结果相一致。分段等效热阻可以作为不同型号防火涂料隔热性能的评价依据，为更准确地进行钢构件的防火设计提供数据参考，并可以辅助分析防火涂料的防火机理。

关键词: 膨胀型防火涂料, 钢结构, 等效热阻, 分段