Fundamental study of damping models with enhanced frequency independence in nonlinear seismic response analysis

Causal hysteretic damping, extended Rayleigh damping, and uniform damping models exhibit frequency-independent damping ratios over a wide frequency range. However, several points remain unclear regarding their applicability to inelastic problems. Therefore, in this study, to compare the vibration characteristics of these damping models, analyses are performed by inputting white noise into simple models with various natural frequencies. Results confirm that these damping models are frequency-independent even under inelastic conditions. Further, the causal hysteretic and extended Rayleigh damping models have the same computation order as that of conventional Rayleigh damping and can therefore be calculated in approximately the same time. This figure shows that the causality-based damping (causal hysteretic damping and extended Rayleigh damping) model can be evaluated with a constant damping rate over a wide range of vibrations. Moreover, these dampings accurately reproduces a nonlinear modal damping model.image