考虑退化效应的超高层钢管混凝土框架侧移性倒塌余裕度研究

This study investigates side-sway collapse margin of super high-rise concrete-filled steel tubular moment-resisting frames (CFT-MRF) subjected to long period ground motions (LPGM). The effects of material and geometric deterioration on collapse margin are evaluated by proposing a novel constitutive relationship incorporating strength and stiffness degradation due to compressive local buckling and tensile low-cycle fatigue fracture. A lumped fiber element model considering deterioration effects is built for equivalent hollow and concrete-filled steel tubular columns. Experiments, numerical simulation and theoretical analysis are addressed to investigate the side-sway collapse capacity of super high-rise CFT-MRFs, which involves (1) deteriorating constitutive model with consideration of normalized compactness ratio and axial load ratio; (2) cyclic tests on key-columns under variable axial load ratios; and (3) quantification of safety margin up to collapse of high-rises subjected to LPGMs. In particular, an E-Defense shaking table collapse test for an 18-story high-rise steel building is utilized for collapse simulation. Through these investigations, deterioration theory, model and design for post-local buckling fracture of CFT beam-columns will be obtained. In addition, propose a safety margin ratio with respect to collapse, and quick evaluation of remaining capacity of existing high-rise CFT-MRFs after main-shock and before after-shocks. This study contributes to the establishment and development of an evaluation system for existing buildings after earthquake.

针对超高层钢管混凝土框架在长周期地震作用下抵抗“侧移性”倒塌安全储备的关键科学问题，即关于材料与几何非线性引起的退化效应对侧移性倒塌安全余裕度的影响：提出考虑了受压局部屈曲和受拉断裂后强度与刚度退化效应的新型材料本构关系，并建立钢管混凝土构件的集中退化纤维单元模型。本项目基于理论分析、试验研究以及数值模拟，对超高层钢管混凝土框架结构在侧移性倒塌中的基础性、关键性问题进行探究，主要包括：（1）考虑截面与材料统一参数和轴压比的退化本构；（2）倒塌关键柱的变动压拉轴压比的低周往复试验研究；（3）基于E-Defense倒塌试验研究长周期地震下抗侧移性倒塌安全系数。通过本项目，将获得钢管混凝土局部屈曲后发生低周疲劳断裂的关键理论、退化模型和设计方法,建立评价超高层钢与钢管混凝土框架抗倒塌的安全余裕度系数，使得超高层结构在主震后余震前的残余性能得到快速地评价，推动震后建筑安全评估体系的建立和发展。

本项目针对超高层钢管混凝土框架在长周期地震作用下抵抗“侧移性”倒塌安全储备的关键科学问题，即关于材料与几何非线性引起的退化效应对侧移性倒塌安全余裕度的影响：提出了考虑受压局部屈曲和受拉断裂后强度与刚度退化效应的新型材料本构关系，并建立了钢管混凝土构件的集中退化纤维单元模型。此外，基于理论分析、试验研究以及数值模拟，对超高层钢管混凝土框架结构在侧移性倒塌中的基础性、关键性问题进行了探究，主要包括：（1）考虑截面与材料统一参数和轴压比的退化本构；（2）倒塌关键柱的变动压拉轴压比的低周往复试验研究；（3）基于E-Defense倒塌试验研究长周期地震下抗侧移性倒塌安全系数。通过本项目，获得了钢管混凝土局部屈曲后发生低周疲劳断裂的关键理论、退化模型和设计方法,建立了评价超高层钢与钢管混凝土框架抗倒塌的安全余裕度系数，使得超高层结构在主震后余震前的残余性能可以得到快速地评价，成果将推动震后建筑安全评估体系的建立和发展。