Detailed energy analysis of a structure coupled with linear absorber or nonlinear energy sink under seismic ground motion

Abstract The performance of linear and nonlinear vibration absorbers is usually quantified by the percentage of energy transfer and dissipation by the absorber damping content. However, in the case of continuous energy input into the structure like seismic ground motion, the amount of energy transferred into the structure depends on the type of the absorber. The current study introduces a detailed approach for energy analysis based on proposing an alternative mathematical model of the structure which considers absolute coordinates, ground displacement, and ground velocity rather than relative coordinates and ground acceleration. This approach gives a clear insight into the energy content of the structure. Furthermore, the study also investigates the effect of vibration absorbers on the actual energy induced into the structure by ground acceleration and on its stiffness characteristics. Accordingly, the effect of applying a linear tuned mass damper (TMD) or a nonlinear energy sink (NES) on the structural energy content is analyzed. Three historic ground acceleration inputs are employed with a considered 9-story structure to ensure reliable energy analysis. The application of the considered three ground acceleration inputs with structure-TMD and structure-NES system allows more energy transfer from seismic ground energy into the structure. The TMD allows more energy transfer from Kobe earthquake ground acceleration than the NES. However, the NES outperforms the TMD by this action with both El Centro and Northridge earthquake ground accelerations. Consequently, energy-based analysis can be considered as useful supplementary approach for further assessment on how vibration absorbers perform in structures subjected to ground acceleration.