基于滑移连接的防屈曲支撑钢框架节点抗震性能研究

防屈曲支撑（BRB）是一种拉压均可全截面屈服耗能而不屈曲的金属阻尼器，在建筑结构的抗震减震设计中得到广泛应用。然而，由于大变形下支撑框架节点存在显著开合效应，在罕遇地震作用下易出现节点板和相邻梁柱构件的提早断裂现象，限制了BRB抗震性能的充分发挥。为此，在总结BRB钢框架节点的现行设计方法及节点失效模式基础上，提出了可释放节点开合效应的滑移连接节点板，采用低摩擦材料减小接触面摩擦力。建立有限元模型，通过与传统焊接节点板对比，分析两种不同连接对节点板、梁柱和BRB受力性能的影响。以此为基础，设计该类节点足尺试验模型，对其进行拟静力试验，分析其在往复荷载下的抗震性能。研究结果表明：所提出的滑移连接可有效释放节点板与梁柱之间的切向约束和开合效应，显著降低了节点板的塑性损伤，实现了罕遇地震作用下节点板弹性的性能目标；梁塑性铰由节点板端部移至梁柱交界面处，降低了梁柱构件的剪力水平和塑性损伤；在层间位移角4%下各关键构件仍具有饱满稳定的滞回性能，显著提高了BRB钢框架的抗震性能。

Seismic performance of sliding gusset connections in buckling-restrained braced steel frame

Buckling-restrained braces (BRB) are metallic yielding dampers which utilize axial yielding to dissipate seismic energy without significant buckling under tension and compression. Due to their stable cyclic behavior, BRBs have been widely adopted to mitigate structural damage. However, seismic performance of buckling-restrained braced frames (BRBFs) is often limited by premature fracture of corner gusset connections and surrounding framing members due to significant frame-gusset interaction under severe earthquakes. In this paper, commonly used design methods and failure modes for corner gussets connection were first reviewed. A novel sliding gusset connection, which utilized bolted end plates between the gusset plate and the beam-column flanges but minimized shear interaction via employment of low-frictional material, was proposed to mitigate the frame-gusset interaction. Finite element models of two beam-column joints incorporating the new and traditional gusset connections were constructed to investigate the effect of different configuration on the structural behavior of the gusset plate, framing members and BRBs. A quasi-static test was conducted on a full-scale joint incorporating the new gusset connection to examine its seismic performance under cyclic loading. It is found that the new connection is effective in minimizing the frame-gusset shear interaction and in reducing plastic damages on the gusset connection. The gusset connection can still remains essentially elastic under severe earthquakes. It is also found to have a minor rigid-zone effect on the framing members and thus, the plastic hinge of the beam shifts back to the original beam-column section and shear forces and plastic damages on the framing members are reduced. All the key structural components exhibite full and stable cyclic performance even at 4% inter-story drift ratio, indicating that the performance of steel BRBF can be significantly improved by using such a sliding gusset connection.