Simplified Damping Modification Factor for Vertical Response Spectra

Damping modification factor of vertical response spectra (DMF<inf>V</inf>) for 1%, 2%, 8% and 10% damping levels with that at 5% of the critical is explored for a period range of 0–4.0 s. The dependence of DMF<inf>V</inf> on seismological parameters (magnitude, epicentral distance and soil type) is studied and is shown to be weak and insignificant for practical purposes. Simplified relation for computing DMF<inf>V</inf> as a function of the period is proposed irrespective of any seismological parameters.