随机地震动下粘滞阻尼减震结构振动台试验研究

为研究随机激励作用时粘滞阻尼器在结构中的实际减振效果，开展了随机地震动作用下粘滞阻尼减震结构振动台试验研究. 振动台试验中，采用基于物理随机地震动模型生成的地震动样本作为台面输入. 通过对有控和无控模型结构响应的均值、标准差以及概率密度函数等进行比较，系统分析了粘滞阻尼器的消能减震效果. 结果表明:有控模型结构层间位移响应显著减小，楼层剪力均方根值取得一定的减振效果，而大多数楼层绝对加速度响应出现不同程度增大；随机地震动作用下模型结构动力响应的变异性显著，且不同试验地震动样本输入时粘滞阻尼器取得的减振效果不同；粘滞阻尼器-钢支撑系统工作时能给被控结构提供一定的附加刚度和附加阻尼，使得结构动力特性产生变化，进而改变结构地震响应；有控模型结构底层位移响应的均值及标准差在地震动作用时段内均显著减小，且底层位移响应在各时刻的概率密度函数的分布宽度及其形态较无控时发生明显变化. 

Shaking Table Test of Model Structure with Viscous Dampers Subjected to Random Earthquake Ground Motions

To investigate the control efficiency of structures installed with viscous dampers subjected to random excitations, shaking table tests on vibration control of a randomly base-driven structure with and without dampers, were conducted. In the experiments, the base excitation was represented by a physical stochastic ground motion model. By comparing the probabilistic characteristics of the responses of the controlled and uncontrolled structures, such as the mean, standard deviation, and the probability density function, the seismic mitigation effect of viscous dampers was systematically analysed. The results show that the interstory drifts of the controlled structure are obviously smaller than those in the uncontrolled cases, and interstory shear forces are reduced to some extent in the root-mean-square sense, while absolute accelerations of most floors increase to different degrees. It was also found that the variability of dynamic responses of the model structure subjected to random earthquake ground motions is very significant, and the control efficiency is different when various representative time histories of ground accelerations are adopted as seismic inputs. Moreover, the working viscous damper-steel support system can provide additional stiffness and damping to the controlled structure, and thus make the structural dynamic characteristics change, which leads to a change in the structural seismic response. Finally, the mean and standard deviation of the bottom floor displacements of the controlled structure are considerably mitigated throughout the whole duration of ground motions, and the distribution width and shape of the probability density function of the displacements at each moment of time, change significantly compared with those in the uncontrolled cases.