钢筋混凝土框架结构防屈曲支撑加固振动台试验研究

为验证某多层钢筋混凝土框架结构采用防屈曲支撑加固后在地震作用下的抗震性能，以实际工程为背景，对未加固结构及采用防屈曲支撑加固结构进行了1/5比例缩尺模型振动台试验，主要研究了模型结构的动力特性、阻尼比、地震反应、防屈曲支撑的耗能能力及震后防屈曲支撑的性能变化。试验结果表明：未加固模型结构在地震输入下未能实现规范的“三水准”抗震目标，采用防屈曲支撑加固后的模型结构改柱铰机制为梁铰机制，地震反应得到有效控制，最大位移降低率达97%；防屈曲支撑在多遇地震作用下仅增加结构抗侧刚度，分担地震剪力约占地震总剪力的34%~49%，设防及罕遇地震作用下防屈曲支撑屈服变形明显，有效提高结构阻尼，耗散的能量占地震输入总能量的25%~51%；不同型号防屈曲支撑震后性能变化有较大差异，防屈曲支撑结构体系的破坏形态为防屈曲支撑首先断裂失效，进而梁柱破坏。

Shaking table test on RC frame structure with buckling restrained braces

To verify the performance of buckling restrained braces (BRB) in reducing the seismic response, the shaking table tests were carried out on two 1/5 scaled models of reinforced concrete frame structures, which were equipped and unequipped with BRB respectively. The dynamic characteristics, damping ratio, seismic response characteristics of model structure and the energy dissipation capacity of BRB were researched. The test results show that: the structure unequipped with BRB fail to achieve the ‘three level’ seismic target. In contrast, the structure equipped with BRB fail in a preferred pattern, where the seismic response is diminished effectively and the maximum reduction rate of displacement reaches 97%; under frequent earthquake, BRB can provide the structure with lateral stiffness, and share up to 34%－49% of the total shear force. Under medium and rare earthquakes, BRB provides the model structure with damping by its yield deformation, and dissipates 25%－51% of the total energy. The test results also show that, different kinds of BRB have a great difference for performance after earthquakes. The failure mechanism of the structural system with BRB is that BRB is broken first, and then the beam and column fail.