悬臂式阻尼桁架在某超高层连体结构中的应用

Application of Cantilever Damping Truss in a Super High-rise Connected Structure

通常,在超高层建筑避难层设置伸臂桁架以改善抗侧刚度,但不可避免会造成结构周期变短、地震力增大,还会引起结构竖向刚度和承载力的突变,从而出现薄弱层和软弱层。在加强层增设悬臂式阻尼桁架,采用粘滞阻尼器耗能,可提高结构动刚度,避免薄弱层的产生。该文对悬臂式阻尼桁架的设计方案、受力机理分析、减震效率等影响参数进行敏感性分析,采用弹塑性时程分析的方法识别粘滞阻尼器在罕遇地震下多条地震波输入后的反应性态。结果表明:1)为提高减震效率,需严格控制悬臂桁架的弹性变形,并采取措施保证桁架平面外的稳定;2)悬臂式阻尼桁架受力机理的实质是利用杠杆原理放大结构的层间位移,变水平位移为竖向位移;3)悬臂式阻尼桁架粘滞阻尼器的阻尼系数C取值越大,减震效果越好,但取值过大,会给桁架和阻尼器的设计带来难度;4)悬臂式阻尼桁架的减震效率与所在楼层的层间位移角正相关,因此宜选择设置在层间位移角最大的楼层;5)该结构在罕遇地震作用下阻尼器的最大出力约3500kN,正向位移约40mm,反向位移约60mm。从收集的相关文献看,悬臂式阻尼桁架运用在超高层连体尚属首次,该文的经验总结可为工程界提供借鉴。

Generally,outrigger trusses are applied on the refuge floor of super high-rise buildings to improve the lateral stiffness,but will inevitably shorten the structural period and increase the seismic forces while causing a sudden change in the vertical stiffness and bearing capacity of the structure,and generate weak layers and soft layers.The adding of a cantilever damping truss to the reinforcement layer,using viscous dampers to dissipate energy,can improve the dynamic rigidity of the structure and avoid the generation of weak layers.This paper conducted a sensitivity analysis on the design scheme,an analysis of the force mechanism,the damping efficiency and other influencing parameters of the cantilever damping truss.The elastoplastic time history analysis method was used to identify the response behavior of the viscous damper after multiple seismic waves were input under rare earthquakes.The results showed that:1)In order to improve the damping efficiency,it is necessary to strictly control the elastic deformation of the cantilever truss,and take measures to ensure the stability of the truss outside the plane;2)The essence of the force mechanism of the cantilever damping truss is to use the principle of leverage to amplify the inter-story displacement of the structure,and shift the horizontal displacement to the vertical displacement;3)The larger the value of the damping coefficient C of the cantilever damping truss viscous damper,the better the damping effect,but if the value is too large,it will bring about difficulties to the design of the truss and damper;4)The damping efficiency of the cantilever damping truss is positively related to the inter-storey displacement angle of the floor where it is located,so it should be set on the floor with the largest inter-storey displacement angle;5)The maximum output of the damper of this structure is about 3500kN under the action of rare earthquakes,the forward displacement is about 40mm,and the reverse displacement is about 60mm.From the collected literature,it is the first time that the cantilever damping truss has been used in the super high-rise conjoined.