薄壁圆钢管混凝土相贯节点动力性能及耗能机制研究

With the development trend of long span and heavy load in modern engineering structures, large concrete-filled steel tubular trusses and laced columns appear constantly. The joints of these structures are mostly circular concrete-filled steel tubular joints, and become thin-walled joints because the diameter thickness ratio of the chord is very large. In order to solve the problem of lacking of the experimental and theoretical basis on the dynamic performance of concrete-filled thin-walled steel tubular (CFTST) joints, the mechanical behavior, failure modes, hysteretic behavior, and restoring force models of the CFTST joints will be studied through the reversed cyclic loading tests and refined finite element simulation. The influence of loading conditions, geometrical parameters, material parameters, and axial load of the chord will be analyzed to find the inherent pattern, and the spatial effect of multi-planar joints will be obtained by comparing with planar joints. Then the ultimate capacity equations of planar joints under different failure modes will be established based on the mechanical models, and the ultimate capacity equations of multi-planar joints will also be established by considering the spatial effect. Finally, according to the energy dissipation mechanisms of the joints under different failure modes, the design method of the joints based on the energy dissipation mechanism will be proposed. This research can not only provide scientific basis for the design of CFTST joints, but also effectively promote the application of CFTST trusses and laced columns, and can promote the improvement and development of the design theory of steel-concrete composite structures.

随着现代工程大跨、重载的发展趋势，大型钢管混凝土桁架式和格构式结构不断出现，这类结构的节点多为圆钢管混凝土相贯节点，且因为主管的径厚比很大而为薄壁节点。为解决薄壁圆钢管混凝土相贯节点所面临的缺少动力性能试验和理论研究基础的问题，本课题拟通过试验研究和精细化有限元模拟，研究薄壁圆钢管混凝土相贯节点在低周反复荷载作用下的受力机理、破坏模式、滞回性能和恢复力模型；揭示荷载类型、几何参数、材料参数和主管轴力的影响规律，对比平面节点探明空间节点的空间效应；基于力学模型建立不同破坏模式下平面节点的承载力公式，进而建立考虑空间效应的空间节点承载力公式；通过探明不同破坏模式下节点的耗能机制，最终提出基于耗能机制的节点抗震设计方法。研究成果不仅可为薄壁圆钢管混凝土相贯节点的工程设计提供科学依据，还能有效的促进薄壁钢管混凝土桁架式和格构式结构的推广应用，同时也是对钢-混组合结构设计理论体系的完善和发展。

随着现代工程大跨、重载的发展趋势，大型钢管混凝土桁架式和格构式结构不断出现，这类结构的节点多为圆钢管混凝土相贯节点，且因为主管的径厚比很大而为薄壁节点。为解决薄壁圆钢管混凝土相贯节点所面临的缺少研究基础的问题，本项目结合试验和有限元参数分析对其动力性能进行了系统的研究。揭示了薄壁圆钢管混凝土相贯节点的破坏模式，探明了荷载类型、主管径厚比、主支管壁厚比对节点的破坏模式和极限承载能力的影响规律。揭示了薄壁圆钢管混凝土相贯节点的承载效率和其影响因素。探明了薄壁圆钢管混凝土相贯节点的耗能机制，在此基础上，提出了基于耗能机制的抗震设计方法。探明了荷载类型、几何参数和主管轴压比对圆钢管混凝土平面相贯节点应力集中系数的影响，基于强度等效的原则，提出了改进的应力集中系数计算公式，公式计算结果和试验结果吻合较好。对比平面节点，探明了空间效应对薄壁圆钢管混凝土空间相贯节点应力集中系数、承载力和破坏模式的影响，提出了薄壁圆钢管混凝土空间相贯节点承载力计算公式。研究成果不仅可为薄壁圆钢管混凝土相贯节点的工程设计提供科学依据，还能有效的促进薄壁钢管混凝土桁架式和格构式结构的推广应用，同时也是对钢-混组合结构设计理论体系的完善和发展。