双金属复合管混凝土柱抗震性能与设计方法研究

Concrete-filled bimetallic tubular (CFBT) structures are in accordance with the green development concept, and possess applicable value in civil engineering due to the economic efficiency and combined advantages of steel-concrete composite structures and bimetallic tubes. Based on the preliminary research on the axial compressive behavior of concrete-filled stainless steel/carbon steel bimetallic tubular stub columns, this project aims to systematically study the seismic performance of CFBT columns subjected to combined constant axial compression and cyclic lateral loads. Non-linear finite element analysis models and theoretical formulas are first established to simulate the full-range response of these composite members, and typical tests are then conducted on the CFBT specimens with different parameters. Based on the numerical, theoretical and experimental results, the failure modes, strength, stiffness, and energy dissipation capacity of the composite specimens are analyzed, and the composite actions between different components are demonstrated. Parametric study is carried out to evaluate the influences of various parameters, such as the shear-span to depth ratio, axial load ratio, material property, and configuration of the bimetallic tubes on the seismic performance of the composite member. Finally, simplified methods are proposed to calculate the strength and stiffness of the CFBT columns. This research could provide reference for the design of CFBT columns, and prompt further applications of these members in engineering structures.

双金属复合管混凝土融合了钢管混凝土和双金属复合管的特点，兼具力学性能和防腐耐久的优势，符合绿色发展理念，且经济可行，具有工程应用价值。本项目拟在前期关于不锈钢(外)-碳素钢(内)复合管混凝土构件轴压性能研究的基础上，进一步系统探索该类组合结构构件在恒定轴压和往复水平荷载共同作用下的抗震性能。建立考虑钢-混凝土组合作用的有限元分析模型和理论公式，并进行不同参数条件下的典型试验。结合数值、理论和试验研究，分析复合管混凝土柱在往复荷载作用下的破坏形态、承载力、刚度和滞回耗能性能，明晰受力全过程中不锈钢层-碳素钢层以及复合管-混凝土的相互作用和共同工作特性。开展系统的参数分析，明确剪跨比、轴压比、材料性能、复合管构造等重要参数对复合管混凝土柱抗震性能的影响规律，提出该类构件承载力和刚度的实用计算方法。本项目的研究成果可为双金属复合管混凝土柱的设计提供依据，促进该类新型结构在实际工程中的推广应用。

双金属复合管混凝土(CFBT)融合了钢管混凝土和双金属复合管的特点，兼具力学性能和防腐耐久的优势，符合绿色发展理念，且经济可行，具有工程应用价值。为系统研究CFBT柱的抗震性能，进行了7根CFBT柱试件和3根CFST柱对比件在恒定轴压和往复水平荷载共同作用下的滞回性能试验，分析了不同轴压比和混凝土强度对CFBT柱破坏形态、承载力、刚度和滞回耗能性能的影响；明晰受力全过程中，复合管基层和复层之间以及复合管与混凝土之间的相互作用和共同工作性能，建立了考虑钢-混凝土组合作用的精细化有线元分析模型，该模型考虑了材料、几何非线性以及混凝土在往复加载时的塑性损伤。试验研究和有限元分析的结果表明，CFBT柱在往复水平荷载作用下呈现出良好的承载力、变形性能、滞回曲线饱满；随着水平位移的增大，CFBT柱的强度和刚度退化不明显，呈现出良好的延性和耗能能力。受力变形过程中，复合管基层和复层的共同工作性能良好，未出现界面分离现象。CFBT柱的水平承载力随轴压比的增大而提升，混凝土强度影响构件的承载力和刚度退化性能。在所考虑的轴压比范围内，CFBT构件在达到1/20层间位移角时仍具有良好的承载力和耗能能力。基于理论和系统的参数分析，探索了不同参数(材料强度、轴压比、复合管复合比等)对CFBT柱抗震性能的影响规律，提出了构件承载力和刚度的实用计算方法和荷载-变形恢复力模型。本项目的研究成果可为CFBT柱的设计提供依据，促进该类结构在实际工程中的推广应用。

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