Seismic Behavior and Design of Connections for CFT Column Systems

钢管混凝土柱-宽翼缘钢梁组合结构是一种有效的组合结构形式。管子的填充增加了系统的刚度和强度。这种结构形式还通过结合结构钢（施工速度、强度、大跨度能力、轻质）和混凝土（刚度、阻尼、经济）的特性，产生了一种非常具有成本效益的结构系统，其中钢管为放置混凝土提供了方便的模板。这种结构的关键要素之一是梁和柱之间的结构连接。作为横向抗震系统的一部分，该连接将能够将梁的力和弯矩传递给柱。由于在荷载作用下产生的非弹性、非均匀、复合应力状态，连接的行为通常是复杂的。目前，关于CFT组合结构抗震性能和抗震设计指南方面的知识还比较缺乏，特别是连接处。本文将重点研究CFT方柱组合结构体系的弯矩连接的抗震性能。目标是：(1)研究梁与相邻柱之间的力和弯矩传递机制，以及连接细节对该机制的影响；(2)开发在地震条件下性能良好且具有成本效益的连接细节；(3)制定在实践中实施细节的设计指南。分析性调查将由两部分组成。第一部分将对开式CFT柱组合体系进行非线性时程地震分析。第二部分将需要对连接进行非线性有限元分析，以评估各种结构细节对连接的力和力矩传递机制和能力的影响。评估混凝土破碎、钢管局部屈曲和板区变形对连接性能的影响。实验项目将包括地震荷载条件下的全尺寸梁柱子组合的建造和测试。这些子组合将类似于原型主题结构内部连接区域的梁柱构件及其连接。测试样品中的每个连接都将包含创新设计，其中延性需求和从分析研究中获得的连接细节信息将用于制定这些设计。实验和分析程序的结果将用于制定设计指南。这是一个由土木基础设施系统（CIS）招标NSF 94-154的第一年项目支持的项目。＊＊＊

9520279 Ricles One efficient means of composite construction is the concrete filled steel tube (CFT) column- wide flange steel beam system. The filling of the tube increases the stiffness and strength of the system. This form of construction also produces a very cost effective structural system by combining the attributes of structural steel (speed of construction, strength, long-span capability, lightweight) and concrete (stiffness, damping, economy), where the tube provides a convenient formwork for placing the concrete. One of the key elements in this type of construction is the structural connection between the beam and column. As part of a lateral seismic load resistant system the connection would be expected to be capable of transferring beam forces and moments to the columns. The behavior of connections is typically complex due to the inelastic, non- uniform, combined stress states that develop under loading. There presently is still a lack of knowledge related to the seismic performance and guidelines for seismic resistance design of CFT composite construction, particularly for connections. This study will focus on the seismic behavior of moment connections for CFT square column composite structural systems. The objectives are to: (1) study the force and moment transfer mechanism between the beams and a adjacent column, and the influence connection details have on this mechanism; (2) develop connection details that perform well under seismic conditions, and are cost effective; and (3) develop design guidelines for implementing the details in practice. The analytical investigation will consists of two parts. The first part will involve conducting nonlinear time history seismic analysis of open CFT column composite systems. The second part will entail conducting nonlinear finite element ana lysis of the connection in order to assess the affects various structural details have on the force and moment transfer mechanism and capacity of the connection. Affects of concrete crushing, steel tube local buckling, and panel zone deformation on connection performance will be assessed. The experimental program will involve the construction and testing of full scale beam column sub- assemblages for seismic loading conditions. These sub- assemblages will resemble the beam and column members and their connection in the interior joint region of the prototype theme structure. Each connection in a test specimen will consist of an innovative design, where the ductility demand and information on connection details obtained from the analytical study will be used to formulate these designs. The results from the experimental and analytical programs will then be used to formulate the design guidelines. This is a project supported under the year 1 program of the Civil Infrastructure Systems (CIS) solicitation NSF 94-154. ***