圆钢管约束型钢混凝土柱-RC梁/钢梁节点抗震性能理论与试验研究

The outer steel tube of tubed steel reinforced-concrete column is discontinuous in the joint zone, because it is interrupted in the beam to column connection. The steel tube will not bear the longitudinal load directly, but will confine the core concrete continuously, so that the compressive strength of composite column is strengthened and ductility of composite column is improved. The tubed steel reinforced-concrete has wide application prospect. The outer steel tube is interrupted in the joint zone, so that the joint zone is weaken. The traditional connection form, which transfer the shear force depending on the outer steel tube, cannot be used. Moreover the related research has not been carried out. The new connections of circular tubed SRC column to RC or steel beam are proposed in this project. The methods of three-dimensional cruciform specimen experiment, simplified model theory analysis and finite element numerical analysis are used to study on the mechanical behavior and seismic mechanism of different connections. The hysteretic behavior, failure mode and restoring force model of connections are proposed. The parameters, which have influence on static force and seismic performance of connection, will be researched. The parameters include beam form, radius-thickness ratio of tube, steel ratio of core steel, strength of materials, axial compression ratio of column, structure of constraint ring beam, joint area with dense hooped reinforcement and composite floor. The simplified calculation models and calculation formula of bearing capacity of press and shear in the joint region are established. Seismic design method and construction measures of connection are proposed. The study results can be used for the formulate and improve the relevant technical standards.

钢管约束型钢混凝土柱的外包钢管在梁柱节点处断开，不通过节点核心区，不直接承担纵向荷载，只对核心混凝土起连续约束作用，提高了组合柱的抗压强度并改善了其延性，具有广泛应用前景。但由于外钢管在节点处断开，节点区偏弱，不同程度依靠外包钢管传递剪力的传统节点无法沿用，而相关研究还未开展。本项目提出了圆钢管约束型钢混凝土柱-RC梁/钢梁节点的新型连接形式，并采用三维十字形试件试验、简化模型理论分析和有限元数值模拟相结合的方法，研究不同连接形式的节点受力性能及其抗震工作机理，揭示其滞回性能和破坏模式，提出节点恢复力模型。综合研究梁形式、钢管径厚比、核心型钢含钢率、材料强度、柱轴压比、约束环梁构造、节点区箍筋加密、组合楼板等因素对连接节点静力和抗震性能的影响，建立节点区受压、受剪的简化计算模型和承载力计算公式，提出节点的抗震设计方法和构造措施，用于制定和完善相关技术标准。

钢管约束型钢混凝土解决了传统钢管混凝土柱中钢管在进入弹塑性阶段后才对核心混凝土产生有效的约束作用，且钢管与混凝土共同承担轴向荷载易引起钢管板件屈曲的问题。钢管约束型钢混凝土柱的外包钢管在梁柱节点处断开，不通过节点核心区，不直接承担纵向荷载，只对核心混凝土起连续约束作用，提高了组合柱的抗压强度并改善了其延性，具有广泛应用前景。节点区是地震作用下容易发生损坏的部位，节点区承载能力或变形能力不足，是导致结构破坏的重要原因。项目对9个圆钢管约束型钢混凝土柱-RC梁/钢梁节点进行了轴压性能试验研究，研究了轴压节点的破坏特征、破坏模式及破坏机理；同时得到了各轴压试件的荷载-应变曲线，荷载-轴向位移曲线以及荷载-侧向位移曲线等。对4种类型，共8个足尺的圆钢管约束型钢混凝土柱-RC梁/钢梁节点的抗震性能进行了低周反复加载试验研究，分析了各节点的破坏特征、破坏模式及破坏机理；通过对关键部件变形和应力检测，得到各足尺节点试件的滞回曲线、骨架曲线、最大塑性转角、强度与刚度退化曲线、极限承载力以及耗能能力等相关抗震性能指标。运用ABAQUS有限元软件，建立了考虑几何、材料和接触非线性的有限元模型，对试验试件进行数值模拟，试验结果与有限元分析结果吻合良好。进而对梁形式、钢管径厚比、核心型钢含钢率、材料强度、柱轴压比、约束环梁构造、钢梁外加强环构造、组合楼板等因素对节点静力和抗震性能影响进行参数分析。提出了节点的抗震设计方法和构造措施。为制定和完善相关设计标准提供可靠依据。项目研究成果具有重大理论意义和工程应用价值，必将推动绿色钢结构建筑在我国的发展应用。