Abstract Steel structures have been increasingly applied in contemporary infrastructures, which always require high loading capacities and strong resistance to disasters such as earthquake actions, fire and environmental corrosion, etc. Recently a superior high-performance (SHP) steel is developed accordingly, possessing combined beneficial features of high-strength, high-ductility, corrosion-resistance and fire-resistance, which may well satisfy the structural requirements. The present study aims to investigate mechanical properties of the SHP steel at elevated temperatures and to propose its constitutive models for further usage in fire design and analyses of structural members. A comprehensive experimental programme including a series of standard tensile coupon tests at both ambient and elevated temperatures is described herein, and key mechanical properties including modulus of elasticity, yield strength, ultimate tensile stress as well as stress-strain curves of the SHP steels are obtained based on the test results. Reduction effects of elevated temperatures on their mechanical properties are quantitatively clarified, and further comparisons with prediction results in accordance with national standards as well as with independent test results reported in literature are made. It is indicated that the mechanical properties of the SHP steels differ significantly from that of conventional mild steel and fire-resistant steel. Specific prediction equations are proposed for evaluating the temperature-dependent mechanical properties of the SHP steel; furthermore, an adapted Ramberg-Osgood model is developed for describing its full range stress-strain relation. The research outcomes of the present research may serve as an essential basis for better understanding mechanical performance of the SHP steel at elevated temperatures as well as for further investigations on its structural members' behaviour; and it is helpful to promote its application in practice.

中文翻译：

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高温下优质高性能钢的机械性能和建模

摘要 钢结构越来越多地应用于现代基础设施中，这些基础设施对承载能力和抗震、火灾、环境腐蚀等灾害的抵抗力要求强。近年来，相应地开发了一种高性能（SHP）钢，具有综合性能。具有高强度、高延展性、耐腐蚀、耐火等优点，可以很好地满足结构要求。本研究旨在研究 SHP 钢在高温下的机械性能，并提出其本构模型，以进一步用于防火设计和结构构件分析。本文描述了包括在环境温度和升高温度下进行的一系列标准拉伸试样测试的综合实验程序，并根据试验结果获得了SHP钢的弹性模量、屈服强度、极限拉伸应力以及应力应变曲线等关键力学性能。定量阐明了高温对其力学性能的还原作用，并与根据国家标准的预测结果以及文献报道的独立测试结果进行了进一步比较。结果表明，小水电钢的力学性能与常规低碳钢和耐火钢有显着差异。提出了具体的预测方程来评估小水电钢的温度相关机械性能；此外，还开发了一个经过调整的 Ramberg-Osgood 模型来描述其全范围应力-应变关系。本研究的研究成果可为更好地了解小水电钢在高温下的力学性能以及进一步研究其结构构件的行为提供重要依据；有利于在实践中推广应用。