粘滞阻尼器减震结构非线性随机振动的时域显式降维迭代随机模拟法

粘滞阻尼器在大型复杂结构减震设计中应用广泛。由于粘滞阻尼器的非线性阻尼力特性,粘滞阻尼器减震结构非平稳随机地震反应分析是一个典型的局部非线性随机振动问题。利用减震结构动力响应时域显式表达式的降维列式优势,仅针对与粘滞阻尼器相关的局部自由度进行非线性迭代计算,提出了局部非线性随机振动问题的时域显式降维迭代随机模拟法,为设置粘滞阻尼器的大型复杂减震结构非线性地震反应分析提供一种高效的随机振动方法。以安装了四个纵桥向粘滞阻尼器的某主跨1200m悬索桥为工程实例,开展E2水准地震激励下的非线性随机振动分析。计算结果显示,设置阻尼器后,主梁的纵桥向位移得到明显控制,降幅达到80%,大桥的关键截面内力也有5%左右的降幅。

Nonlinear random vibration analysis of energy-dissipation structures with viscous dampers by random simulation method based on explicit time-domain dimension-reduced iteration scheme

Viscous dampers are widely used in the design of large-scale complex energy-dissipation structures.Due to their intrinsic nonlinear behavior of damping forces,the nonstationary seismic analysis of a structure with viscous dampers is fundementally a random vibration problem with local nonlinearities.With the advantage of dimension-reduced representation of the time-domain explicit expressions for dynamic responses of an energy-dissipation structure,only those local degrees of freedom related to viscous dampers are required for nonlinear iterative computation.A random simulation method based on explicit time-domain dimension-reduced iteration scheme is then proposed to solve random vibration problems with local nonlinearities.The present approach can serve as a high-efficiency random vibration method for nonlinear seismic analysis of large-scale complex structures with viscous dampers.A nonli-near random vibration analysis is carried out under random seismic excitations of level E2 for a suspension bridge with a main span of 1200m equipped with 4 viscous dampers.Numerical results show that the longitudinal displacement of the main girder of the bridge is greatly reduced at a ratio of 80% due to the installation of viscous dampers,and the internal forces at critical sections of the bridge are decreased by about 5% as well.