The present study was undertaken to characterize the structural behavior and ultimate flexural strength of steel plate I-girders under pure flexural moment at elevated temperatures. A novel design procedure along with flexural design curves was proposed to predict the flexural behavior of the I-girders and estimate corresponding ultimate flexural strengths. The main strategy of the procedure is to find an ambient-temperature equivalent of the I-girder by quantifying and formulating the effects of elevated temperatures. The proposed procedure comprises overall and partial phases. The former phase deals with the determination of equivalent laterally unbraced length, and the latter phase addresses the equivalent web and compression flange slenderness parameters. The calibration factor was defined to adapt the design curves to the effects of high compression flange slenderness parameters and residual stress at elevated temperatures. To generate comparative results, a numerical study was conducted by analyzing 216 finite element (FE) models. Fifty-four out of 216 FE models with different cross-sectional elements were dedicated to the I-girders fail by yield or local buckling failure mode, the results of which are reported in the present paper. Data fitting analysis was carried out to capture the variation of calibration factor with respect to compression flange slenderness parameters. By calibrating the proposed design procedure, the results were converged and, therefore, good conformity was reached between the numerical and parametric results.

中文翻译：

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高温下钢板工字梁的弯曲设计曲线：具有屈服或局部屈曲破坏模式的工字梁

本研究旨在表征钢板工字梁在高温下纯弯矩下的结构行为和极限抗弯强度。提出了一种新颖的设计程序和弯曲设计曲线来预测工字梁的弯曲行为并估计相应的极限弯曲强度。该程序的主要策略是通过量化和公式化高温的影响来找到 I 梁的环境温度等效值。拟议的程序包括总体阶段和部分阶段。前一阶段涉及等效横向无支撑长度的确定，后一阶段涉及等效腹板和压缩翼缘长细度参数。定义校准系数以使设计曲线适应高温下高压缩法兰细长参数和残余应力的影响。为了生成比较结果，通过分析 216 个有限元 (FE) 模型进行了数值研究。216 个具有不同横截面元素的有限元模型中有 54 个专门用于 I 梁屈服失效或局部屈曲失效模式，其结果在本论文中报告。进行数据拟合分析以捕获校准因子相对于压缩法兰长细度参数的变化。通过校准所提出的设计程序，结果得到了收敛，因此数值结果和参数结果之间达到了良好的一致性。