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火灾时的大空间单跨门式刚架结构抗火性能,受钢构件温升和结构整体抗火临界温度的影响。本文通过对无保护大空间建筑钢构件温升数据的统计分析,获得包含火源功率、建筑体积、钢构件截面形状系数的钢构件温升拟合公式;结合单跨门式刚架结构整体抗火临界温度数据的统计分析,获得包含荷载比、柱高和系数K的结构整体抗火临界温度拟合公式;通过分析上述因素对钢构件温度变化率及抗火临界温度变化率的影响,获得各个因素的客观权重值,并应用于具体案例的结构安全分析。结果表明,在本文的研究条件下,荷载比权重值最大,约为0.4;火源功率是仅次于荷载比的一个重要因素;建筑体积、截面形状系数和系数K三者都在其自身值较小时,权重值较大,且都随着其自身值的增加,权重值降低。本研究可供无保护门式刚架结构建筑的抗火设计、火灾风险评估和消防管理作参考。
The fire resistance of large space single-span portal frame structures under fire is affected by the temperature rise of steel members and the overall critical fire-resistant temperature of the structure. Based on the statistical analysis of the temperature rise data of unprotected large building steel members, the fitting formula of steel member temperature rise including the power of fire source, the building volume and the sectional shape coefficient of steel members is obtained. Through the statistical analysis of the critical temperature data of fire, the fitting formula of the overall critical fire resistance temperature of the structure including load ratio, column height and coefficient K is obtained. By analyzing the influence of the above factors on the temperature change rate of steel components and the rate of change of critical fire temperature, The objective weights of various factors are applied to the structural safety analysis of specific cases. The results show that under the condition of this study, the weight ratio is the largest, about 0.4. The power of fire source is an important factor next only to the load ratio. The building volume, the cross-sectional shape coefficient and the coefficient K are all within their own values When smaller, the weight value is larger, and as its value increases, the weight value decreases. This study can be used as reference for fire-resistant design, fire risk assessment and fire management of unprotected portal frame structures.