防屈曲支撑角部节点板与钢框架的相互作用效应

Interaction between corner gusset connections of buckling-restrained braces and steel frame

防屈曲支撑是一种高效稳定的耗能减震装置,其与框架结构一般通过焊接节点板形式连接。目前节点板连接设计方法仅考虑支撑轴力的影响,并没有直接考虑框架开合效应(梁柱在水平地震力下产生的张开/闭合变形)的不利作用,导致焊接节点板在连接处提前发生开裂。通过有限元模拟的方法,同时考虑开合效应和支撑轴力的共同影响,对防屈曲支撑钢框架与角部节点板连接的相互作用进行研究。有限元模型共5组,主要参数包括节点板尺寸、节点板与框架的连接形式以及节点板是否设置自由边加劲肋。在连接形式方面,提出了一种可减小开合效应不利影响的新型可滑移螺栓连接节点板,并与传统焊接节点板的受力性能进行比较。分析结果表明,平面尺寸较小的焊接节点板对结构的抗侧刚度影响最小,可减小设置防屈曲支撑的子框架所分担的地震剪力,相应的节点板受力性能也优于平面尺寸较大的焊接节点板;在焊接节点板上设置自由边加劲肋并不能明显改善其受力性能;所提出的新型可滑移螺栓连接节点板可有效减小节点板对结构刚度的影响,以及框架开合效应对节点板的不利影响,是一种在消能钢框架支撑体系中具有应用前景的新型节点板连接。

Buckling-restrained braces( BRBs) are a new type of high-performance hysteretic dampers. BRBs are generally connected to frame structures by gusset plates which are welded to beam and column. However,the axial force of BRB is only considered into the current design approach of gusset plate while the effect of seismic frame action is generally ignored,leading premature fracture of gusset connection. In this study,the interaction between BRB corner gusset connection and steel frame is discussed by finite element method,and the effect of both BRB axial force and frame action is considered. Five FEM models were constructed by ABAQUS and the parameters of the models included the size of gusset plate,the connection type between gusset plate and frame,and free edge stiffener. A new type of gusset plate with sliding end plate and bolted connections to frame structure was proposed and comparison was made between the traditional and new gusset connections. The analysis results showed that compared with the gusset plate with larger size,smaller gusset plate dimension had smaller effect on the stiffness of frame structures which could reduce the seismic shear carried by the beams and columns. Also,smaller gusset plate exhibited better structural performance. The performance of gusset plate could not be significantly improved by providing free edge stiffeners onto the gusset plate. However,the negative effect of frame action and gusset plate on the stiffness of frame structures could be significantly reduced by adopting the proposed new gusset plate with sliding end plate,showing a promising gusset connection in steel bucklingrestrained braced frame structures.