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

组合结构的一种有效方法是利用高性能钢管混凝土柱。钢管的填充增加了刚度和强度，克服了高强度钢管潜在的局部失稳。钢管约束高强混凝土，增加其延性。该组合系统具有高性能结构钢（施工速度，强度，大跨度能力，重量轻）和高性能混凝土（刚度，阻尼，经济）的属性，同时使用管作为模板。在抗震设计中，构件的合理比例和结构体系的平衡是必不可少的。目前对钢管混凝土柱的抗震性能还缺乏认识。特别是当使用高性能混凝土和高性能钢材时，需要为CFT组合结构的抗震设计提供合理的指导。本研究主要针对钢管混凝土构件在抗弯及支撑框架中的基本性能进行研究。其目标是：（1）研究了钢管高强混凝土异形柱在重力和水平地震荷载作用下的荷载-变形响应，（2）建立了基于试验结果的钢管高强混凝土异形柱地震响应分析模型和计算方法，并对模型进行了修正;以及（3）为采用高强度材料建造的钢管混凝土柱制定设计指南和建议。调查员将从事分析和大规模实验研究。首先研究钢管混凝土短柱，探讨各种设计参数对构件力-变形和弯矩-曲率-推力关系的影响。从实验研究的结果将被用来开发和校准各种分析模型预测的CFT的响应组合轴向和弯曲载荷。这些模型将包括面向设计的强度预测方程和基于纤维的公式，用于容量和整体力-变形响应预测。第二部分将研究长钢管混凝土柱在轴向和横向循环荷载作用下的性能，并考虑设计参数的影响。使用该模型进行参数研究，以扩大实验数据库。研究结果将用于制定设计指南。所获得的知识和开发的设计指南将导致这种形式的建筑的实用和可靠的设计，以及开发高强度混凝土和钢材料在抗震设计中的使用。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。这是一个在NSF倡议的第二年计划下支持的项目。复合材料和混合结构的日本合作研究，'NSF 94-154。

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.