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

钢管混凝土柱钢-混凝土组合结构由于混凝土的存在而提高了其抗火性能，是一种很好的抗火设计方案。加拿大国家研究理事会的研究人员对钢管混凝土柱的耐火性能进行了大量的研究。然而，这些研究都牢牢地植根于目前的规定性耐火设计理念。目前，有一个显着缺乏知识的基本力-变形行为的钢管混凝土梁-柱承受高温，由于火灾荷载。这种力-变形行为的知识将导致基于性能的指导方针，用于设计CFT柱的耐火复合结构。拟议的研究项目提供了两个领域的实验和分析研究：（1）基本的力-变形特性;（2）各种材料的影响（钢材屈服应力和混凝土强度）和几何参数（钢管宽度和B/t比）对火灾高温下钢管混凝土梁柱性能的影响。实验研究将使用创新的和专门设计的测试方法对大规模CFT试样进行。分析调查将涉及火灾荷载下CFT试样的热和结构（力学）行为的三维有限元模型的开发和验证。经验证的模型将用于进行分析参数研究。从实验和分析研究的结果将被用来校准一个宏纤维为基础的有限元建模CFTs，可用于调查火灾荷载下的CFT框架的结构行为。

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.