Abstract Ultra-high strength concrete (UHSC) and high strength steel (HSS) have been found to be attractive alternatives to normal strength materials for high-rise construction. The uses of HSS and UHSC can reduce member sizes and payload acting on foundation, which will free up more usable floor space and require less construction materials and handling works. The combination of them to form concrete-filled steel tubular (CFST) columns is more attractive compared with the columns employing either UHSC or HSS due to enhanced strength and stiffness. To better understand the structural behavior of CFST columns using UHSC and HSS, experimental and analytical studies on their fire resistance are presented in this paper. Fire tests were carried out on square S690 HSS tubes infilled with C170/185 UHSC to form the CFST columns. The fire resistance time under Standard ISO fire was recorded and checked against the conventional simple calculation model of EN1994-1-2 and the newly proposed axial force and moment interaction model. It is revealed that the column buckling curve in EN1993-1-1 can be used for fire-resistant design of CFST columns employing UHSC and HSS when the load level is less than 0.65. The use of UHSC is beneficial to improve the fire resistance of CFST columns but the use of high strength steel is not when compared with their counterparts using normal strength materials.

中文翻译：

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超高强混凝土受压高强钢管的耐火性能

摘要 超高强度混凝土 (UHSC) 和高强度钢 (HSS) 已被发现是用于高层建筑的普通强度材料的有吸引力的替代品。HSS 和 UHSC 的使用可以减少构件尺寸和作用在基础上的有效载荷，这将释放更多可用的地面空间，并需要更少的建筑材料和搬运工作。与采用 UHSC 或 HSS 的柱相比，由于增强了强度和刚度，将它们组合形成钢管混凝土 (CFST) 柱更具吸引力。为了更好地了解使用 UHSC 和 HSS 的 CFST 柱的结构行为，本文介绍了其耐火性的实验和分析研究。在填充有 C170/185 UHSC 以形成 CFST 柱的方形 S690 HSS 管上进行了防火测试。记录标准 ISO 火灾下的耐火时间，并对照 EN1994-1-2 的常规简单计算模型和新提出的轴力和力矩相互作用模型进行检查。结果表明，EN1993-1-1中的柱屈曲曲线可用于当荷载水平小于0.65时采用UHSC和HSS的CFST柱的耐火设计。使用 UHSC 有利于提高 CFST 柱的耐火性，但与使用普通强度材料的同行相比，使用高强度钢则不然。结果表明，EN1993-1-1中的柱屈曲曲线可用于当荷载水平小于0.65时采用UHSC和HSS的CFST柱的耐火设计。使用 UHSC 有利于提高 CFST 柱的耐火性，但与使用普通强度材料的同行相比，使用高强度钢则不然。结果表明，EN1993-1-1中的柱屈曲曲线可用于当荷载水平小于0.65时采用UHSC和HSS的CFST柱的耐火设计。使用 UHSC 有利于提高 CFST 柱的耐火性，但与使用普通强度材料的同行相比，使用高强度钢则不然。