Abstract Advanced High-Strength Steels (AHSS) have high potential to be adopted in future innovative infrastructure. However, the material properties of AHSS at elevated temperature, which are necessary for analysis and design in the fire situation, are not yet specified in design codes or literature. An experimental investigation is carried out on cold-formed steels with nominal yield stress ranging from 340 MPa to 1200 MPa. The tested materials include two types of advanced high-strength steels (dual-phase (DP) and martensitic (MS) steel) and two conventional steels (high-strength low-alloy (HSLA) and mild steel). 88 tensile specimens are tested in steady-state and transient-state conditions at temperatures up to 700 °C. Material properties are obtained from the tests including elastic modulus, 0.2% proof stress, yield stresses at strain levels of 0.5%, 1.5%, and 2%, ultimate stress, and elongation at fracture. The test results are compared with the design codes provisions in Eurocode 3 and AISC 360, and with data from existing literature. Comparisons show that cold-formed DP and MS steels exhibit relatively larger reduction in stiffness and strength than conventional cold-formed steels at elevated temperature, which warrant the development of specific provisions. It is also found that transient-state tests at 5 °C/min heating rate yield approximately similar yield stress retention factors as steady-state tests but yield lower values of elastic modulus retention factors. New predictive models are proposed to determine the mechanical properties at elevated temperature of the cold-formed advanced high-strength steels with nominal yield stress up to 1200 MPa.

中文翻译：

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先进高强度合金钢的高温材料特性

摘要 先进高强度钢 (AHSS) 在未来的创新基础设施中具有很高的应用潜力。然而，AHSS 在高温下的材料特性对于火灾情况下的分析和设计是必需的，但在设计规范或文献中尚未规定。对标称屈服应力范围为 340 MPa 至 1200 MPa 的冷弯型钢进行了实验研究。测试的材料包括两种高级高强度钢（双相 (DP) 和马氏体 (MS) 钢）和两种常规钢（高强度低合金 (HSLA) 和低碳钢）。在高达 700 °C 的温度下，在稳态和瞬态条件下测试了 88 个拉伸试样。材料特性是从测试中获得的，包括弹性模量、0.2% 弹性模量、应变水平为 0.5%、1.5% 和 2% 时的屈服应力、极限应力和断裂伸长率。将测试结果与 Eurocode 3 和 AISC 360 中的设计规范规定以及现有文献中的数据进行比较。比较表明，冷成型 DP 和 MS 钢在高温下表现出比传统冷成型钢相对较大的刚度和强度降低，这需要制定具体规定。还发现在 5 °C/min 加热速率下的瞬态测试产生与稳态测试大致相似的屈服应力保持因子，但产生较低的弹性模量保持因子值。提出了新的预测模型来确定标称屈服应力高达 1200 MPa 的冷成型高级高强度钢在高温下的机械性能。