火灾下薄壁异形截面铝合金轴心受压柱耦合屈曲及承载力计算

Ultimate Strength and Buckling Interaction of Thin-Walled Aluminum Alloy Columns with Irregular Cross Section under Axial Compression in a Fire

利用有限元方法,对薄壁异形截面铝合金轴心受压柱在火灾不同温度下的破坏模态和屈曲承载力进行了研究。有限元模型通过试验进行验证,并采用稳态分析的方法考虑火灾高温的影响。研究了火灾高温对该类截面柱破坏模态的影响,证实火灾高温会降低柱的屈曲承载力,但不会改变柱的破坏模态。利用有限元方法分析了不同长细比的铝合金柱在不同温度下的屈曲承载力,并将有限元结果与根据欧洲规范EN1999-1-2的计算结果进行对比。结果表明,该规范的设计方法不能准确计算薄壁异形截面铝合金轴压柱的抗火承载力。在有限元分析的基础上提出了针对薄壁异形截面柱高温下承载力的修正公式。

Failure modes and ultimate strength of thin-walled aluminum alloy columns with irregular cross section are investigated using finite element model（FEM）under axial compression in a fire.The finite element model is validated using test results,and the effect of high temperatures on aluminum alloy columns is accounted in steady state analysis.Out-of-plane deformation of each plate along the column,as well as cross sectional stress development under different temperatures are presented.Based on the analysis results,the ultimate strength of column decreases,while the failure mode is not affected by temperatures.Ultimate strength results of aluminum alloy columns obtained from finite element analysis（FEA）are compared with those calculated using EN1999-1-2.The results show that design method provided by EN1999-1-2 cannot accurately predict the ultimate strength of thin-walled aluminum alloy columns with irregular cross section.A modification to the design method in EN1999-1-2 is proposed.