超大截面钢管混凝土柱钢-砼协同工作机制及设计方法研究

Concrete-filled steel tubular(CFT) columns have manifested a number of advantages, such as favourable load-bearing behavior and construction facility. They have been widely applied as vertical load-bearing members for mega frame-corewall hybrid structure in the extra-high buildings. Generally, connections between giant column and tansfer girders or trusses beared huge vertical loading in the extra-high building structures. In practical structures,loadings on CFT columns generally transfer to the wall of steel tube firstly. Therefore,the current design method for load-bearing capacity of CFT columns which assumed that the total cross section bear external load is unsafe when there is not enough core concrete to participate in transferring the shearing force from transfer girders or trusses.This project will aim to investigate the relevant basic theory about mechanical properties of CFT columns with super large cross section in the extra-high buildings,including:(1)investigation on suitable construction measures for purpose of effectively cooperative work between steel tube and core concrete and their working mechanism in the CFT columns with super large cross section;(2)research on load-bearing properties of CFT columns with super large retangular cross section with the distributive beam;(3)the design method for load-bearing capacity of CFT columns with super large retangular cross section with the distributive beam. The research achivements will provide test data support and theoretical basis for load-carrying capacity design method for CFT columns with super large retangular cross section in extra-high buildings,which will be of great theoretical significance and practical application prospects.

钢管混凝土柱以其受力性能和施工工艺上的众多优点，在国内外超高层建筑中经常被用作巨型框架-核心筒混合结构的竖向承重构件。此时，巨型柱与大型转换梁（或转换桁架）的梁柱节点区将承受巨大的竖向荷载。而实际结构中，钢管混凝土柱所受到的外荷载一般先作用于钢管壁，若梁柱节点区没有足够的核心混凝土及时参与承担大型转换梁（或转换桁架）的剪力，钢管混凝土柱按全截面承载的设计方法将偏于不安全。本项目拟针对超高层建筑中超大截面矩形钢管混凝土柱力学性能的相关基础理论开展研究，主要包括：①超大截面矩形钢管混凝土柱钢管-混凝土协同工作的合理构造措施和工作机理研究；②设置分配梁的超大截面矩形钢管混凝土柱承载性能研究；③设置分配梁的超大截面矩形钢管混凝土柱承载力设计方法研究。研究成果将为超高层建筑中超大截面矩形钢管混凝土柱的承载力设计方法提供试验数据和理论依据，具有重要的理论意义和应用前景。

重点针对本项目提出的设置分配梁构造的超大截面矩形钢管混凝土柱共同工作机制及传力构造承载力设计方法进行研究。主要工作和成果如下：1）对保证钢-砼协同工作的构造措施力学性能与工作机理进行研究，对分配梁传力构造进行了缩尺试验与大量精细化有限元数值分析，确定了分配梁屈服机制、破坏模式及荷载传递机理，得到分配梁承载力设计方法，并提出分配梁的截面构造要求；2）设传力构造的超大截面矩形钢管混凝土柱承载性能研究：完成了轴压构件试验与压弯构件力学试验，对承载性能进行了理论分析；3）设传力构造的超大截面矩形钢管混凝土柱承载力设计方法研究：将第二部分试验结果与中美相关规范进行比较分析，得出我国《矩形钢管混凝土结构技术规程》（CECS159:2004）中钢管混凝土轴压、压弯构件承载力设计方法同样适用于超大截面钢管混凝土柱，可以为相关工程设计提供参考。