用附加防屈曲支撑钢筋混凝土框架加固既有钢筋混凝土框架抗震性能试验研究

利用附加防屈曲支撑（BRB）钢筋混凝土框架对既有钢筋混凝土框架结构进行减震加固。设计3榀钢筋混凝土框架，其中2榀为附加设置BRB加固框架的钢筋混凝土框架，另外1榀为纯钢筋混凝土框架以作对比。通过低周反复加载试验，验证所设计的外贴防屈曲支撑钢筋混凝土框架加固既有钢筋混凝土框架的可行性。分析既有及外贴钢筋混凝土框架的开裂、荷载 侧移滞回曲线、骨架曲线、荷载 防屈曲支撑变形曲线，以及等效黏滞阻尼比和等效刚度等特性。结果表明：所设计的附加钢筋混凝土框架、预埋件、连接构造受力可靠，附加设置BRB的钢筋混凝土加固框架具有良好的减震耗能能力；水平荷载-侧移滞回曲线圆润饱满；防屈曲支撑在小层间位移角下可屈服耗能，大位移下不失效，耗能稳定；附加框架能够显著增加既有钢筋混凝土框架结构的阻尼，有效降低地震反应，改善既有框架结构抗震性能。

Experimental study on seismic behavior of concrete frame retrofitted with additional

This paper mainly studied the problems and demand of seismic strengthening of RC frame structure, and proposed a fast and efficient seismic strengthening method, which used the concrete-tube buckling-restrained braces and buckling-restrained braced frames. Three frame specimens were designed, manufactured and tested under reversed cyclic loadings, including one original frame and two buckling-restrained braced frames with different brace types, i.e. monoclinic brace and herringbone brace. The test demonstrates the feasibility of the additional buckling-restrained braced frames, which was designed according to this paper. Seismic performances of the additional buckling-restrained braced frames, such as concrete element cracks, lateral load-displacement loops, skeleton curves, BRB load-deformations forces of RC frame, the equivalent viscous damping ratio and tangent stiffness, etc, were studied. The results show that the additional buckling-restrained braced frames, the embedded parts and the connecting constructions are reliable, and the additional buckling-restrained braced frames show excellent seismic force reduction and energy dissipation capacity. The system has rich and stable hysteretic load-displacement curves. The BRB yields at low inter-story drift angle, and can keep effective at large lateral inter-story drift angle. It is validated that the equivalent viscous damping can thus be increased, the seismic response be reduced, and then the structural performance be improved.