Amplification of Rocking Due to Horizontal Ground Motion

Abstract

This paper addresses the fundamental behavior of rocking structures by investigating the rate of energy input due to horizontal ground motion. This perspective indicates that the assumption of initial at-rest conditions may be inappropriate, and identifies ground motions which cause ‘rocking resonance’ for various constraints. Furthermore, the ability of multiple impulses to either reduce or amplify the rocking response is demonstrated, and motivates the use of statistical assessment procedures to predict rocking stability during earthquakes. In this context, past earthquake data is used to generate an array of synthetic earthquakes of a given intensity which are applied to determine the overturning probability of the rocking block. The results emphasize the time dependence of the rocking response. Finally, simulation of the rocking response to real earthquake records confirms that multiple impulse rocking amplification may be significant.