基于弹性波动力学理论的结构阻尼

引入弹性应力波阻抗的概念,利用阻抗与阻尼在一定条件下相等的方法来确定结构的初始阻尼,为结构振动分析计算中阻尼参数的选取提供一种实用性较强的方法.理论分析证实基于弹性波动力学理论下粘滞阻尼理论及复阻尼理论在杆的轴向振动及梁的横向振动中的一致性,可应用这种方法来确定杆式结构及梁式结构的阻尼特性参数分布.通过这种方法确定的福泉高速公路江兜分离式立交桥简支板梁对应于第一阶振型的阻尼比为5.556%,该桥环境随机振动试验中采用半功率(带宽)法求得的板梁不同测点处相应的阻尼比介于5.02%～5.54%,试验结果说明这种方法在工程实践中应用是可行的.

Structural damping coefficient based on elastic stress wave theory

The conception of stress wave impedance is introduced and a practicable method to select damping parameter in structural dynamic analysis is presented,in which the impedance and damping are considered to be numerically equal to each other under a given condition in calculation of the initial structural damping coefficient.Theoretical analysis has verified the consistency of viscous damping theory and complex damping theory based on the elastic stress wave theory for both rods in axial vibration and beams in transverse vibration.This approach can be applied to determine the parameter distribution of structural damping characteristics.Taking Jiangdou Grade-separation of Fu-Quan Expressway as an example,the calculated damping ratio of simply supported plate beams for the first mode amounts to 5.556%,and the corresponding damping ratio at the varying observation points of the plate beams lies between 5.02% and 5.54% by means of half-power method in an ambient random vibration test.The results demonstrate the validity of the developed approach to engineering practice.