被动消能混合式交错桁架单元滞回性能有限元分析

为了增强交错桁架耗能能力,可在桁架单元的斜腹杆上设置摩擦耗能器,形成被动消能交错桁架结构。采用有限元软件ANSYS12.1分析摩擦耗能器在不同摩擦系数、螺栓孔长以及螺栓等级下的荷载位移关系,并将摩擦耗能器的荷载-位移关系转化为等效应力-应变关系,定义到斜腹杆上的等效耗能器单元的材料本构关系中,对被动消能桁架单元进行水平方向循环加载,得到各桁架单元的滞回曲线、骨架曲线以及耗能能力图。有限元分析结果表明:摩擦系数使耗能器的滑移力达到斜腹杆屈曲荷载的96%时,结构的耗能能力最好;耗能器孔长越大,桁架的耗能能力和延性越好,滑移量达到桁架节间距的1%时,延性系数可满足一般框架的抗震要求;螺栓等级越高,其预紧力越稳定,桁架耗能能力越好。

Finite Element Analysis on Hysteretic Performance of Passive Energy Dissipation Composite Staggered Truss

In order to enhance energy dissipation capacity of composite staggered truss,truss can be obtained by installing the friction dampers in diagonal web members,using finite element analysis software ANSYS12. 1 to simulate the energy dissipation of friction dampers in the different coefficient of friction,length of hole and strength class of bolts; transforming the load-displacement relation of friction damper into equivalent stress-strain relation,then defined as the constitutive relation of equivalent damper units in diagonal web members,acting on monotonic loading and cyclic loading in horizontal direction,getting the hysteretic curves,skeleton curves and energy dissipation capacity. The results show that when the coefficient of friction dampers slip force equal 96 percentage of yield load of diagonal web members,truss performs best in energy dissipation and stiffness. With the length getting longer,energy dissipation capacity and ductility performance of truss is better; the higher the level of bolt is,the pretension of bolts can be hold stably,truss have better energy dissipation capacity.