铰接隅撑钢框架抗震性能研究

Seismic performance of knee-braced steel frame with hinged joints

传统抗弯钢框架的梁柱节点通常设计为刚性连接,这种刚性节点具有很大的抗弯刚度,然而节点延性不足,罕遇地震作用导致节点脆性断裂。研究学者提出了多种解决该问题的思路,例如半刚性连接节点、节点加强或削弱方法使塑性铰外移等。本文提出了一种简化的梁柱节点连接方式-铰接连接,改变梁柱节点的传力方式,在节点处设置隅撑提供框架的抗侧刚度,控制结构的失效模式。本文设计了三组抗弯钢框架和铰接隅撑钢框架,分别为3层、5层和8层结构,通过Pushover分析和非线性动力时程分析,对比二者之间的承载力、刚度、延性和层间侧移等抗震性能。研究结果表明:铰接隅撑钢框架具有和传统抗弯钢框架相似的抗侧刚度,且承载能力略高。罕遇地震作用下,铰接隅撑钢框架的层间侧移较小。传统抗弯钢框架失效模式为梁端出现塑性铰,而铰接隅撑钢框架的塑性区域转移至隅撑与梁连接部位。

Rigid joints are usually adopted for the beam-to-column moment connections of the conventional steel.These beam-to-column joints have excellent flexural stiffness,but are vulnerable to brittle fracture under severe earthquakes due to lack of ductility.Researchers have put forward a variety of ways to solve this problem,such as using the semi-rigid joint,reinforcing the connections or reducing the beam section.This paper proposes a simplified beam-to-column connection-hinge joint.The connection is achieved by changing the force transfer mode of beam and column joints and setting knee brace at the joint for provideing suffcient the lateral stiffness of the frame,so that the failure mode of the structure can be controlled.The moment-resisting frames and knee-braced frames of different stories are designed,including three stories,three stories and eight stories.Pushover analysis and nonlinear dynamic analysis are carried out,and the bearing capacity,lateral stiffness,ductility and story drift are compared between the frames.The results indicated that the knee-braced steel frame has the same lateral stiffness as the moment-resisting steel frame,and presents slightly higher bearing capacity.The story drifts of the knee-braced steel frame under severe earthquakes are smaller than moment-resisting frame.As to the failure mode,plastic hinge occurs at the beam-to-column joint in the moment-resisting steel frame while the plastic area is transferred to the connection between the knee-brace and the beam in the knee-braced steel frame.