异形钢管混凝土埋入式柱脚节点传力机理与设计方法

异形钢管混凝土具有布置灵活和避免柱角外凸等优点，在多高层建筑中具有广阔的应用前景，但由于截面不规则，异形钢管混凝土柱脚受力机理与普通钢管混凝土柱脚并不相同，不能直接套用现有设计方法，阻碍了异形钢管混凝土的推广应用。本项目将对抗震性能优越的异形（L形和T形）钢管混凝土埋入式柱脚传力机理进行系统性试验研究、有限元模拟和理论分析。分别研究竖向荷载、水平荷载及复合受力下埋入式柱脚受力性能，分析轴力下柱脚不规则冲切面形成机制，建立不同方向水平荷载下异形钢管与基础混凝土不均匀压应力简化分布模型，揭示复合受力下柱脚轴力、弯矩和剪力传递机理。提出考虑柱截面形状、埋置深度和栓钉连接件布置方式等影响的异形钢管混凝土埋入式柱脚抗冲切、抗弯和抗剪简化受力模型和承载力计算方法，提出柱脚合理构造措施和设计方法，确定异形钢管混凝土柱脚合理埋置深度与基础高度，为相关规范制定和工程应用提供依据。

Special-shaped concrete-filled steel tubular (CFST) column has broad application prospects in high-rise buildings, because it has the advantages of flexible layout and avoiding the convex of the column. However, due to the irregular section, the load transfer mechanisms of special-shaped CFST column base are different from those of the ordinary CFST column base. The design methods of ordinary CFST column base cannot directly be applied to the special-shaped CFST column base, which hinders the wide application of special-shaped CFST columns. The systematic experimental research, numerical and theoretical analysis will be carried out in this project on the load transfer mechanism of the embedded special-shaped CFST column base, which has a superior seismic performance. The performance under vertical load, horizontal load and combined load will be studied on such embedded column base. Then the formation mechanism of irregular punching surface of such column base under axial force is analyzed, a simplified distribution model of non-uniform compressive stress between special-shaped steel tube and foundation concrete under horizontal load in different directions is established, and the transfer mechanism of axial force, bending moment and shear force of column base under combined load are revealed. Based on the researches, the simplified models and calculation methods for punching, bending and shearing resistance of such column base are proposed, considering the influences of column sections, embedded depth and headed studs. The construction measures and design methods are suggested and then the reasonable embedded depth and foundation height of such column base could be determined. The research work in this project can provide a reference for the design specifications and engineering applications.