Abstract This paper describes a series of four full-scale furnace tests conducted on unprotected concrete-filled steel tubular columns with and without reinforcement bars. Three of the columns were subjected to compression and horizontal loads, considering the end restraints provided by the adjacent cooler frame members and the forced displacement caused by thermal elongation of the heated beam during fire. One of the columns was subjected to concentric load for the purpose of benchmark comparison. The test setup consisted of multi-loaded specimens that comprised two-story columns which were subjected to compression load. The lower column was subjected to an ISO-834 standard fire and a displacement control horizontal force was applied to the top of the column until a horizontal displacement of 1/50th of the heating length of the column was attained after 2 or 4 h of fire. The test results showed that the failure times of the columns under multi-loading conditions were shorter than those of the columns under axial loading condition because of the double curvature bending on the core concrete. The double curvature bending was observed to be more severe than the single curvature bending in the eccentrically loaded furnace test.

中文翻译：

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多荷载作用下无保护钢管混凝土柱耐火性能试验研究

摘要 本文描述了在带和不带钢筋的无保护钢管混凝土柱上进行的一系列四次全尺寸炉试验。考虑到相邻冷却器框架构件提供的端部约束以及火灾期间受热梁的热伸长引起的强制位移，其中三个柱承受了压缩和水平载荷。为了进行基准比较，其中一根柱子承受了同心载荷。测试装置由多载荷试样组成，这些试样包括承受压缩载荷的两层柱子。下部柱子经受 ISO-834 标准火灾，并在柱子顶部施加位移控制水平力，直到在火灾 2 或 4 小时后达到柱子加热长度的 1/50 的水平位移. 试验结果表明，由于核心混凝土的双曲率弯曲，多荷载工况下柱的破坏时间比轴向荷载工况短。在偏心加载炉试验中，观察到双曲率弯曲比单曲率弯曲更严重。试验结果表明，由于核心混凝土的双曲率弯曲，多荷载工况下柱的破坏时间比轴向荷载工况短。在偏心加载炉试验中，观察到双曲率弯曲比单曲率弯曲更严重。试验结果表明，由于核心混凝土的双曲率弯曲，多荷载工况下柱的破坏时间比轴向荷载工况短。在偏心加载炉试验中，观察到双曲率弯曲比单曲率弯曲更严重。