Smooth Spectra of Horizontal and Vertical Ground Motions

Abstract

An improved method of constructing a smooth-response spectrum from peak values of ground acceleration, velocity, and displacement (pga, pgv, and pgd) is presented. Improved dynamic amplification factors are presented for applying damping adjustments to the spectral accelerations or to backcalculate pga, pgv, and pgd from spectral accelerations. Horizontal-to-vertical spectral ratios are analyzed for rock and soil sites to allow the construction of a vertical design spectrum from a given horizontal design spectrum.