A study on damping modification factors for structures under near-fault, far-fault and artificial earthquakes

摘要

This paper examines the damping modification factors which are applied to adjust elastic response spectral values corresponding to 5% of viscous damping to other higher or lower damping levels. Empirical expressions are proposed for displacement, velocity and acceleration response spectra, both for near- and far fault earthquakes, where four types of soil conditions, from hard rock to soft soil are considered. This study also examines,. for the first time, the influence of artificial earthquakes on damping modification factors. It confirms that, in contrast to the considerations of many seismic codes, damping modification factors are strongly depended on the period of structural vibration while there are significant problems of using the same modification factor to estimate maximum displacement, velocity and seismic forces. Furthermore, it is found that the fault distance has not impact on damping modification factors while artificial earthquakes lead to quite different factors in comparison with the natural records.