Performance of the Uniform Damping Model in Seismic Analysis of Isolated Structures Under Near-Field and Far-Field Ground Motions
Yuan Tian , Siying Chen , Junrong Liu , Zhongxian Liu
Earthquake Engineering and Resilience ›› 2025, Vol. 4 ›› Issue (3) : 336 -353.
Performance of the Uniform Damping Model in Seismic Analysis of Isolated Structures Under Near-Field and Far-Field Ground Motions
The damping model can influence the results of seismic response analyses of structures. This effect is particularly pronounced under elastic and weakly nonlinear conditions, where damping-induced energy dissipation plays a crucial role and directly affects the structural response. Moreover, the influence of damping models may vary depending on the characteristics of ground motion excitations. Conventional viscous damping models may involve mass-proportional and geometric-stiffness-proportional components, which are associated with incorrect dissipation of energy in rigid-body modes. This issue is especially relevant for base-isolated buildings, where rigid-body motions can be substantial. In response to these limitations, recent research has proposed new complex damping models for time-history analysis. This study investigates the effects of different damping models on isolated structures by comparing the performance of uniform damping (a type of complex damping) with that of Rayleigh damping (a type of viscous damping). The evaluation is conducted using 30 near-field and far-field ground motions. First, the impact of damping models on response spectra for various damping ratios is examined. Then, dynamic responses of typical seismically isolated composite frame structures using different damping models under different ground motions are analyzed and compared. The results indicate that higher-order structural responses, such as acceleration, are more sensitive to the choice of damping model than lower-order responses like displacement. Specifically, uniform damping tends to produce larger acceleration responses. The differences between the models increase with the damping ratio; for instance, at a damping ratio of 30%, acceleration response spectrum differences can exceed 70% at certain periods. Additionally, Rayleigh damping results in more than 10% smaller deformation estimates for seismic isolation bearings, potentially leading to unconservative designs.
far-field ground motion / pulse-like ground motion / Rayleigh damping / seismic isolated structure / uniform damping
2025 Tianjin University and John Wiley & Sons Australia, Ltd.
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