A Way to Take Predominate Period into Account in Site Classification

Abstract

In order to take the predominate period Tp into account in site classification，a formula is adopted as the relation between VS20 with Vs30 and Tp. The Tp of 233 sites with data of shear wave velocity profiles from NGA-west2 databank are calculated by two approaches. Site categories of the 233 sites are classified from the formula and their values of VS30 and Tp. The coincidences of the results with the site categories from the profiles directly show that the Tp by Quarter-wavelength Approximation is better than that from Tp' by H/V spectral ratio.