设置可更换连梁的双筒体混凝土结构振动台试验研究

Shaking table tests of double tube concrete structure with replaceable coupling beams

设置可更换连梁的结构,通过可更换连梁改变连梁塑性发展机制,将罕遇地震作用下的破坏集中于连梁中部可更换构件而两端连接梁保持弹性工作状态,震后更换损伤的构件便可快速恢复结构使用功能,符合可恢复功能结构的设计理念。设计制作两个1/5缩尺比的双筒体混凝土结构模型,通过振动台试验,对比研究了设置可更换连梁结构与普通连梁结构的结构振动特性及动力反应。结果表明,设置可更换连梁的结构前两阶自振频率随地震动幅值加大而下降的趋势一致;各楼层峰值加速度反应的变化规律基本相同,加速度放大系数基本保持一致;设置可更换连梁后结构的残余变形减小,震后残余位移最大值为1.26 mm,对应的残余位移角最大值为0.14%,可恢复能力较好;混凝土连梁纵筋应变最大值始终比普通连梁结构小,可更换构件能够集中损伤,保证连梁混凝土部分完好;峰值加速度为0.8g的地震波输入前,墙根部纵筋应变减小。

Replaceable device in coupling beam is a type of device, which is installed in the structure to change the plastic development mechanism of the coupling beam. During strong earthquakes, damage occurs in replaceable devices whereas the connecting beams at two ends remain elastic, and the damaged devices could be replaced after earthquake, which complies well with the idea of earthquake resilient structure. Two 1/5 scaled double-tube concrete model structures were designed and tested on the shaking table. The dynamic properties and seismic reactions were compared through the tests. The results indicate that, comparing to the normal structure, the degradation trend with the increase of PGA of the first two natural frequencies of the structure with replaceable coupling beam are the same ; the varying pattern of the floor maximum acceleration and the acceleration amplification are similar; the residual displacement is reduced and the maximum floor residual displacement is 1.26 mm, corresponding to 0. 14% maximum floor residual drift ratio, which shows a good resilient capacity of the new structure; the maximum rebar strain in the RC beam section is lower and the replaceable device could concentrate damage and keep the rest intact; the rebar stain in the shear wall base is also alleviated before PGA is less than 0. 8g.