Finite-element (FE) analysis was used to compare the high-temperature responses of steel columns with two different stress–strain models: the Eurocode 3 model and the model proposed by National Institute of Standards and Technology (NIST). The comparisons were made in three different phases. The first phase compared the critical buckling temperatures predicted using forty-seven column data from five different laboratories. The slenderness ratios varied from 34 to 137, and the applied axial load was 20% to 60% of the room-temperature capacity. The results showed that the NIST model predicted the buckling temperature as or more accurately than the Eurocode 3 model for four of the five data sets. In the second phase, thirty unique FE models were developed to analyze the W8 × 35 and W14 × 53 column specimens with the slenderness ratio about 70. The column specimens were tested under steady-heating conditions with a target temperature in the range of 300°C to 600°C. The models were developed by combining the material model, temperature distributions in the specimens, and numerical scheme for non-linear analyses. Overall, the models with the NIST material properties and the measured temperature variations showed the results comparable to the test data. The deviations in the results from two different numerical approaches (modified Newton–Raphson vs. arc-length) were negligible. The Eurocode 3 model made conservative predictions on the behavior of the column specimens since its retained elastic moduli are smaller than those of the NIST model at elevated temperatures. In the third phase, the column curves calibrated using the NIST model was compared with those prescribed in the ANSI/AISC-360 Appendix 4. The calibrated curve significantly deviated from the current design equation with increasing temperature, especially for the slenderness ratio from 50 to 100.

中文翻译：

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材料模型对预测钢柱火灾行为的影响

有限元 (FE) 分析用于比较具有两种不同应力应变模型的钢柱的高温响应：欧洲规范 3 模型和美国国家标准与技术研究院 (NIST) 提出的模型。比较是在三个不同的阶段进行的。第一阶段比较了使用来自五个不同实验室的 47 个柱数据预测的临界屈曲温度。长细比从 34 到 137 不等，施加的轴向载荷为室温容量的 20% 到 60%。结果表明，对于五个数据集中的四个，NIST 模型预测的屈曲温度与 Eurocode 3 模型一样准确或更准确。在第二阶段，开发了 30 个独特的有限元模型来分析长细比约为 70 的 W8 × 35 和 W14 × 53 柱试件。在目标温度范围为 300°C 至 600°C 的稳定加热条件下对色谱柱样品进行了测试。这些模型是通过结合材料模型、试样中的温度分布和非线性分析的数值方案而开发的。总体而言，具有 NIST 材料特性和测得的温度变化的模型显示的结果与测试数据相当。两种不同数值方法（改进的 Newton-Raphson 与弧长）的结果偏差可以忽略不计。欧洲规范 3 模型对柱试样的行为做出了保守的预测，因为它的保留弹性模量在升高的温度下小于 NIST 模型的那些。在第三阶段，