黏滞阻尼伸臂桁架布置对超高层建筑抗震性能的影响

Influence of outrigger truss with viscous dampers arrangement on seismic performance of super high-rise building

超高层建筑中利用伸臂桁架布置黏滞阻尼器,可避免传统刚性伸臂桁架所带来的不利影响。为探讨伸臂桁架布置形式对超高层建筑结构中黏滞阻尼器的减震效果和对局部构件受力的影响,以一个8度区、407m高的巨型斜撑框架-核心筒结构为例,通过动力弹塑性时程分析,研究黏滞阻尼伸臂桁架分别按通过内柱或避开内柱直接由核心筒悬挑两种方案设计时结构的整体抗震性能和构件内力。结果表明:两种设计方案均可有效协同核心筒和外框架共同受力,但当伸臂桁架经过内柱且弦杆布置在楼面时,因桁架端部受楼面约束,黏滞阻尼器变形受到限制,不能充分发挥作用。当伸臂桁架改为避开内柱、直接由核心筒悬挑,且弦杆脱离楼板约束可自由变形时,黏滞阻尼器耗能能力大幅提升,即使主体结构因塑性损伤产生一定偏位,黏滞阻尼器仍可适应变形继续耗能;因黏滞阻尼器耗能作用明显,主体结构变形得到有效控制,与其相连的巨柱和核心筒负担减轻,结构抗震性能得到一定改善。

In super high-rise building, outrigger truss with viscous dampers could avoid the adverse effects caused by the traditional rigid outrigger truss. The effect of the viscous dampers and the seismic energy dissipation of tall building are studied trough static and dynamic nonlinear analysis method. The influence of structure seismic performance and the member force are analyzed when the outrigger truss dampers set by inner column or core wall. The results show that the internal forces between the core wall and out frame could effectively cooperate by two modes. However, the effect of the viscous dampers couldn’t fully work when the outrigger truss passed through the inner column and the chords are arranged on the floor which the deformation of the dampers is limited. When the outrigger truss directly cantilevered by the core wall the energy dissipation capacity of the viscous dampers could be improved greatly because the truss chords could be freely deformed without the restraint of the floor, even if the structure is damaged the viscous dampers could still fit the deformation and dissipate energy. Due to the obvious energy dissipation effect of the viscous dampers, the deformation of the structure is controlled effectively, the burden of the mega columns and the core walls are reduced, and the seismic performance of the structure is improved.