Seismic Behavior and Design of High Performance Concrete- Filled Steel Tube Columns

组合结构的一种有效方法是采用高性能钢管混凝土柱。钢管的填充增加了高强度钢管的刚度和强度，克服了潜在的局部失稳。管子限制了高强混凝土，增加了其延展性。该组合体系具有高性能结构钢(施工速度、强度、大跨度、轻质)和高性能混凝土(刚度、阻尼力、经济性)的属性，同时采用钢管作为模板。在抗震设计中，构件的合理比例和结构体系的良好平衡是必不可少的。目前，对钢管混凝土柱的抗震性能缺乏了解。钢管混凝土组合结构的抗震设计需要合理的准则，特别是在使用高性能混凝土和高性能钢材的情况下。本文主要研究钢管混凝土构件的基本性能及其在抗弯框架和支撑框架中的应用。研究的目的是：(1)研究高强混凝土和钢组成的非圆形钢管混凝土柱在重力和水平地震共同作用下的荷载-变形反应；(2)根据试验结果建立和校准用于预测钢管混凝土柱在地震荷载作用下反应的分析模型和计算方法；(3)制定高强材料钢管混凝土柱的设计准则和建议。调查员将进行分析性和大规模的实验调查。本文将首先对钢管混凝土短柱进行研究，研究各种设计参数对构件受力-变形和弯矩-曲率-推力关系的影响。试验研究的结果将被用来开发和校准各种分析模型，以预测钢管混凝土对轴向和弯曲组合荷载的响应。这些模型将包括面向设计的强度预测方程，以及基于纤维的能力和总力变形响应预测公式。项目的第二部分将考虑设计参数的影响，研究钢管混凝土长柱在轴向和侧向循环荷载共同作用下的性能。利用这些模型，将进行参数研究，以扩大实验数据库。结果将被用来制定设计指南。所获得的知识和制定的设计准则将导致这种结构形式的实际和可靠的设计，以及在抗震设计中发展高强混凝土和钢材的使用。该项目还涉及与日本和德国大学的密切合作，这将提高研究质量。该项目是美国国家科学基金会(NSF)“美日-复合材料和混合结构合作研究”(NSF 94-154)第二年计划资助的一个项目。

One efficient means of composite construction is that which utilizes high performance concrete filled steel tube (CFT) columns. The filling of the tube increases the stiffness and strength and overcomes potential local instability of high strength steel tube. The tube confines the high strength concrete, increasing its ductility. The combined system has the attributes of high performance structural steel (speed of construction, strength, long-span capability, lightweight) and high performance concrete (stiffness, damping, economy), while using the tube as formwork. It is imperative in seismic resistant design that the members be properly proportioned and the structural system be well balanced. Currently there is a lack of knowledge of the seismic behavior of CFT columns. Rational guidelines for the seismic design of CFT composite construction are needed particularly when high performance concrete and high performance steel are used. This research focuses on basic behavior of CFT members with application to moment resisting and braced frames. The objectives are to: (1) study the load-deformation response of non-circular CFT columns composed of high strength concrete and steel under combined gravity and lateral seismic loading; (2) develop and calibrate a analytical models and computational methods based on experimental results for predicting the response of CFT columns under seismic loading conditions; and (3) develop design guidelines and recommendations for CFT columns constructed of high strength materials. The investigator will involve pursuing analytical and large-scale experimental investigations. Short CFT columns will be first studied, in which the effects of various design parameters on a member's force-deformation and moment-curvature-thrust relationship will be investigated. The results from the experimental studies will be utilizes to develop and calibrate various analytical models for predicting the response of a CFT to combined axial and flexural loading. These models will include design-oriented strength prediction equations and fiber-based formulations for capacity and overall force-deformation response prediction. The second part of the project will investigate the behavior of long CFT columns subjected to combined axial and lateral cyclic loading, considering the effects of the design parameters. Using the models a parametric study will be conducted to expand the experimental data base. The results will be used to formulate the design guidelines. The knowledge acquired and design guidelines developed will lead to the practical and reliable design of this form of construction as well as develop the use of high strength concrete and steel materials in seismic resistant design. This project also involves close collaboration with Japanese and Germany Universities which will enhance the quality of research. This is a project supported under the second-year program of NSF initiative `U.S.-Japan-Cooperative Research on Composite and Hybrid Structures,` NSF 94-154.