Experimental and Analytical Investigations of the Fire Behavior of CFT Beam-Columns

钢管混凝土柱的钢-混凝土组合结构由于其混凝土的存在而增强了耐火性能，因此是耐火设计的优秀候选者。加拿大国家研究委员会的研究人员对CFT柱的耐火性能进行了重要的研究。然而，这些研究都牢牢扎根于当前规范的防火设计理念。目前，由于火灾荷载引起的高温下，CFT梁柱的基本受力变形行为的知识明显缺乏。了解这种力-变形行为将为设计含CFT柱的耐火复合结构提供基于性能的指导方针。拟议的研究项目在两个方面提供了实验和分析调查：(1)基本力-变形行为；(2)各种材料（钢屈服应力和混凝土强度）和几何参数（管宽和b/t比）对CFT梁柱在火灾加载高温下行为的影响。实验研究将采用创新和专门设计的试验方法对大型CFT试件进行。分析研究将涉及开发和验证三维有限元模型的热和结构（力学）行为的CFT样品在火荷载下。经过验证的模型将用于进行分析参数研究。实验和分析研究的结果将用于校准基于宏观纤维的有限元模型，该模型可用于研究CFT框架在火灾荷载下的结构行为。

Steel-concrete composite structures with concrete-filled steel tube (CFT) columns are an excellent candidate for fire resistant design due to their enhanced fire resistance resulting from the presence of concrete. Researchers at the National Research Council of Canada have conducted significant research on the fire resistance of CFT columns. However, these studies were firmly rooted in the current prescriptive fire-resistant design philosophy. Currently, there is a significant lack of knowledge of the fundamental force-deformation behavior of CFT beam-columns subjected to elevated temperatures due to fire loading. Knowledge of this force-deformation behavior will lead to performance-based guidelines for designing fire-resistant composite structures with CFT columns.The proposed research project provides experimental and analytical investigations in two areas: (1) the fundamental force-deformation behavior and (2) the influence of various material (steel yield stress and concrete strength) and geometric parameters (tube width and b/t ratio) on the behavior of CFT beam-columns subjected to elevated temperatures from fire loading. The experimental investigations will be conducted on large-scale CFT specimens using an innovative and specially designed test method. The analytical investigations will involve the development and validation of 3D finite element models for the thermal and structural (mechanics) behavior of CFT specimens under fire loading. The validated models will be used to conduct analytical parametric studies. The results from the experimental and analytical studies will be used to calibrate a macro fiber-based finite element for modeling CFTs that can be used to investigate the structural behavior of CFT frames under fire loading.