Abstract This paper investigates the flexural-torsional buckling behaviour of concrete-filled steel tubular circular arches under mechanical and thermal loading. A thermo-elastic pre-buckling analysis is first conducted by employing the principle of virtual work to derive the non-linear equations of equilibrium. The governing geometrical, equilibrium and constitutive material relations are numerically solved as a system of first-order differential equations with boundary conditions of pinned or fixed ends. The prebuckling analysis is then generalised to consider basic creep strain which is found to have a negligible impact on the prebuckling response under short-term heating. Subsequently, an elastic out-of-plane buckling analysis is performed using energy methods and the influence of thermal loading on buckling loads is examined. The results show that stability boundaries decrease with an increase in thermal loading, and that the rate of reduction is independent of the type of end-supports. Additionally, a Finite Element (FE) model is developed to analyse the inelastic lateral buckling strength of CFST arches under both uniform thermal and fire loading. The FE analysis is validated by comparison to the numerical method derived herein for the elastic buckling analysis.

中文翻译：

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钢管混凝土拱在高温下的面外稳定性

摘要 本文研究了钢管混凝土圆拱在机械载荷和热载荷作用下的弯扭屈曲行为。首先进行热弹性预屈曲分析，利用虚功原理推导出非线性平衡方程。控制几何、平衡和本构材料关系作为一阶微分方程组进行数值求解，边界条件为固定端或固定端。然后将预屈曲分析推广到考虑基本蠕变应变，发现在短期加热下对预屈曲响应的影响可以忽略不计。随后，使用能量方法进行弹性平面外屈曲分析，并检查热载荷对屈曲载荷的影响。结果表明，稳定性边界随着热载荷的增加而减小，并且减小的速率与端部支撑的类型无关。此外，还开发了有限元 (FE) 模型来分析 CFST 拱在均匀热载荷和火载荷下的非弹性横向屈曲强度。有限元分析通过与本文推导出的弹性屈曲分析的数值方法进行比较来验证。