Abstract Experimental and numerical studies on the fire resistance of cold-formed steel (CFS) columns with built-up box-shape sections were conducted in this paper. A series of coupon tensile tests were also performed before the fire resistance tests of the columns to obtain the stress–strain relationship of the steel plate from 20 °C to 800 °C. As a benchmark, the load-bearing capacity tests of the columns at ambient temperature were conducted first, and then the fire resistance tests were performed for eight specimens considering different load ratios and axial restraining stiffness. Afterward, numerical models, including heat transfer and structural analyses, were developed to reproduce the fire-resistance behavior of the columns and verified via test results. Finally, parametric analyses were performed to investigate the influence of load ratio, axial restraint, and rotational restraint on the fire-resistance behavior of the columns. Results indicated that the primary failure mode of the specimens was a combination of local and global flexural buckling, which was sensitive to the longitudinally non-uniform temperature field. Moreover, the increase in load ratio and axial restraining stiffness led to a significant decrease in the critical temperature and failure time. Moreover, even a low level of rotational restraint could enhance the fire-resistance behavior of the column.

中文翻译：

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高温下轴向约束冷弯型钢组合箱柱的试验和数值研究

摘要 本文对组合箱形截面冷弯型钢（CFS）柱的耐火性能进行了试验和数值研究。在柱的耐火试验之前还进行了一系列试样拉伸试验，以获得钢板从 20°C 到 800°C 的应力-应变关系。作为基准，先进行柱在常温下的承载能力试验，然后考虑不同载荷比和轴向约束刚度对8个试件进行耐火试验。之后，开发了包括传热和结构分析在内的数值模型来重现柱的耐火性能，并通过测试结果进行验证。最后，进行参数分析以研究载荷比、轴向约束和旋转约束对柱的耐火性能的影响。结果表明，试件的主要失效模式是局部和整体弯曲屈曲的组合，对纵向非均匀温度场很敏感。此外，载荷比和轴向约束刚度的增加导致临界温度和失效时间的显着降低。此外，即使是低水平的旋转限制也可以增强柱的耐火性能。对纵向非均匀温度场敏感。此外，载荷比和轴向约束刚度的增加导致临界温度和失效时间的显着降低。此外，即使是低水平的旋转限制也可以增强柱的耐火性能。对纵向非均匀温度场敏感。此外，载荷比和轴向约束刚度的增加导致临界温度和失效时间的显着降低。此外，即使是低水平的旋转限制也可以增强柱的耐火性能。