Abstract Based on the performance of Q550 (yield strength fy = 550 MPa) high-strength steel, mechanical property tests at room temperature and elevated temperatures were first carried out. Second, fire tests were carried out on 8 unconstrained Q550 high-strength steel columns with rectangular sections under axial compression. The mechanical properties and failure modes of high-strength steel columns under fire exposure were revealed. Finally, ABAQUS finite element software was used to establish a refined finite element model of high-strength steel columns, and numerical simulation analysis was carried out to analyse the influence of various parameters on the fire resistance. The results show that (1) the critical temperature and the maximum axial displacement of the steel columns decrease with increasing load ratio n. (2) the smaller the slenderness ratio λ is, the smaller the maximum axial displacement, while the critical temperature changes slightly. (3) there are two failure modes of the specimens: overall buckling and overall and local coupling buckling. (4) the thermal mechanical coupling analysis method can effectively simulate the behaviour of high-strength steel columns under fire exposure. The research in this paper establishes a theoretical foundation for the improvement of the fire resistance design method of high-strength steel columns.

中文翻译：

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矩形截面高强钢柱轴压抗火试验研究与数值模拟分析

摘要 基于Q550（屈服强度fy = 550 MPa）高强钢的性能，首先进行了室温和高温力学性能测试。其次，对8根无约束矩形截面Q550高强钢柱进行了轴压试验。揭示了火灾暴露下高强度钢柱的力学性能和破坏模式。最后利用ABAQUS有限元软件建立高强钢柱精细化有限元模型，并进行数值模拟分析，分析各参数对耐火性能的影响。结果表明：（1）钢柱的临界温度和最大轴向位移随着荷载比n的增加而降低。(2)长细比λ越小，最大轴向位移越小，而临界温度变化不大。(3) 试件的破坏模式有整体屈曲和整体局部耦合屈曲两种。(4)热力学耦合分析方法可以有效模拟高强钢柱在火灾暴露下的行为。本文的研究为高强钢柱耐火设计方法的改进奠定了理论基础。(4)热力学耦合分析方法可以有效模拟高强钢柱在火灾暴露下的行为。本文的研究为高强钢柱耐火设计方法的改进奠定了理论基础。(4)热力学耦合分析方法可以有效模拟高强钢柱在火灾暴露下的行为。本文的研究为高强钢柱耐火设计方法的改进奠定了理论基础。