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随着近年来火灾造成财产和生命的损失,大家已越来越重视建筑结构的耐火设计。尽管冷弯薄壁型钢结构的应用日益增加,但其耐火性能并没有得到很好的研究。屈曲模型(如局部或畸变屈曲模型)对冷弯型钢受压杆件的影响较大,并决定了杆件极限承载力的大小。因此,对其进行了基于试验和数值分析的研究,以了解冷弯薄壁型钢在模拟的火灾条件下的畸变屈曲性能。选择0.6,0.8,0.95mm三种厚度和低、高强度型钢(G250、G550型钢)的带-不带附边卷边槽钢。在高温环境下进行多达150个压缩试验,提出受测压杆的有限元模型,考虑了机械性能随温度升高而下降。有限元分析和试验结果表明,提出的有限元模型能模拟环境温度高达800℃情况下的畸变屈曲和承载力性能。经验证的模型能确定机械性能、几何缺陷和残余应力对畸变屈曲性能和冷弯型钢柱承载力的影响。详细的数值研究结果表明,要了解火灾中冷弯型钢柱可靠的承载力特性,采用准确的高温下机械性能是非常重要的。
With the loss of property and life caused by the fire in recent years, people have paid more and more attention to the fire-resistant design of the building structure. Despite the increasing use of cold-formed thin-walled steel structures, their fire-resistant properties have not been well studied. Buckling models (such as local or distorted buckling models) have a greater impact on the bar members of cold-formed steel and determine the ultimate bearing capacity of bars. Therefore, based on the experimental and numerical analysis of the study, to understand the cold-formed thin-walled steel in the simulation of the fire conditions of the distortion buckling performance. Select 0.6,0.8,0.95 mm thickness and low, high strength steel (G250, G550 section) with - without crimping channel. Up to 150 compression tests were carried out in a high temperature environment, and the finite element model of the tested bar was proposed, considering that the mechanical properties decreased with increasing temperature. Finite element analysis and experimental results show that the proposed finite element model can simulate the distorted buckling and bearing capacity under the condition of ambient temperature up to 800 ℃. The validated model can determine the effect of mechanical properties, geometric imperfections and residual stresses on the buckling behavior and on the bearing capacity of cold-formed steel columns. The detailed numerical results show that it is very important to understand the mechanical properties of cold-formed steel columns in fire with reliable mechanical properties under high temperature.