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.