墙式连接金属阻尼器RC框架振动台试验研究

Shaking table test on RC frame installed with metallic dampers using wall-pattern connections

为研究金属阻尼器墙式连接方式的有效性,检验金属阻尼器对RC框架的减震效果,设计并制作1/4缩尺的4层无控结构(纯框架)和减震结构(设置金属阻尼器)振动台试验模型。选取一条人工合成地震动和Takatori天然地震动,调幅到不同地震动强度进行振动台试验,对模型结构动力特性(自振频率、阻尼比)和结构响应(位移、加速度、剪力)进行对比研究。试验结果表明:金属阻尼器同时给结构提供附加刚度和附加阻尼,减震结构的整体刚度始终大于无控结构,减震结构的阻尼比相比于无控结构大幅增加,减震结构的位移响应控制效果显著。金属阻尼器的墙式连接形式具有足够的稳固性和有效性,小震下连接部位无损伤,中震下连接部位出现细微裂缝,大震下结构梁与墙肢交界处出现剪切裂缝,但仍能够保证连接的可靠性。基于试验数据得到的阻尼器位移占比为0.4~0.6,在后续研究中,应进一步研究如何保证较大的阻尼器位移占比,以充分发挥阻尼器的作用。此外,近断层地震动对结构地震响应的影响仍需进一步研究。

To examine the effectiveness of the wall-pattern connection and control effects of metallic dampers,four-story frames without and with metallic wall dampers( namely uncontrolled structure and controlled structure) were designed and built at a scale of 1/4 for shaking table tests. One artificial ground motion and the Takatori earthquake were selected and scaled to different earthquake intensities for the shaking table tests. Dynamic characteristics( including fundamental frequency and damping ratio) and structural responses( including displacement,acceleration and shear force) of the test models were compared. The experimental results indicate that metallic wall dampers can provide additional stiffness and additional damping at the same time. The structural stiffness of the controlled structure is always larger than that of the uncontrolled structure,and the damping ratio of the controlled structure is greatly increased compared with that of the uncontrolled structure. The control effect on displacement of the controlled structure is remarkable. The wall-pattern connection method of metallic dampers has sufficient stability and effectiveness. For the connecting part,no damage was observed under service level earthquake and micro-crack occurred under design basis earthquake. Shear cracks were observed at the intersection between beam and connecting wall under the maximum considered earthquakes,but the reliability of the connections can be ensured. The displacement ratio of dampers attained from test results ranged from 0. 4 to 0. 6. It is necessary to study how to ensure a large displacement ratio of the dampers,so that the effectiveness of the dampers in future research can be improved. In addition,the influence of near-fault ground motion on structural seismic response shall be studied further.