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为研究高温火直接作用下钢梁的抗火性能,对其进行了高温火直接作用试验;同时,以受热时间作为变化参数,对比分析了高温火直接作用和按ISO 834标准升温过程钢梁的轴力、跨中挠度及耐火时间。结果表明:高温火直接作用与按ISO834标准升温下,钢梁破坏端面的微观组织及升温过程的受力和变形存在明显差异;无论有无防火涂层的保护,当温度800℃时,高温火直接作用下钢梁的最大轴力比按ISO 834标准升温的增大76.9%以上;同时,防火涂层厚度对钢梁的耐火时间也有影响,无防火涂层时,钢梁的耐火时间小于20 min;有防火涂层保护时,随防火涂层厚度增厚,两种高温作用下,钢梁的耐火时间相近,但防火涂层厚度不足15 mm时,耐火时间相差20%以上;当防火涂层厚度为15 mm时,在温度约800℃高温火直接作用下,其耐火时间为26 min。
In order to study the fire resistance of the steel beam under the direct action of high temperature fire, the direct fire experiment of the steel beam was conducted. At the same time, taking the heating time as the parameter of variation, the direct action of high temperature fire and the steel beam Axial force, mid-span deflection and fire-resistant time. The results show that there exists a significant difference in the microstructure of the steel beam and the stress and deformation during the heating process according to the direct action of high temperature and the temperature rising according to ISO 834. No matter the protection of fire protection coating, when the temperature is 800 ℃, The maximum axial force of the steel beam under direct action increases by 76.9% or more according to the ISO 834 standard. Meanwhile, the thickness of the fireproof coating also affects the fire resistance time of the steel beam. When the fireproof coating is not used, the fire resistance time of the steel beam is less than 20 min. When the thickness of the fireproof coating is increased, the fire resistance of the steel beam increases with the increase of the thickness of the fireproof coating. When the thickness of the fireproof coating is less than 15 mm, the fire resistance time is more than 20% When the layer thickness is 15 mm, the refractory time is 26 min at a temperature of about 800 ℃.