Generation Mechanism of V_non, the Apparent Residual Vertical Velocity in Strong Motion Records

Abstract

In previous studies, it was suggested that integrating the vertical component of strong acceleration records in time domain often yields a residual velocity, which is always negative. This study proposes a generation mechanism of this residual velocity V_non; at the moment of the action of a horizontal inertia force, the sensor is tentatively tilted in that direction and the horizontal inertia force multiplied by sinθ is felt by the vertical sensor, where θ is the tilt angle. The tilt can be either due to the shear deformation of the ground or the tilt of the house. The apparent residual velocity generated by this mechanism is always negative. It was shown for the K-NET records for which the effect of the housing is small that the proposed mechanism can readily explain the order of magnitude of the observed V_non values.