Abstract
Intermittent aftershocks can occur in a long period after a strong mainshock. There is a high risk that aftershocks may result in further damage to structures damaged in main-shocks, and hamper retrofitting of important structures.
This paper aims to clarify seismic response of a long-span cable-stayed bridge damaged by a mainshock, subjected to intermittent aftershocks. Seismic analyses of the bridge subjected to a mainshock, and followed artificial successive aftershocks are conducted. Based on the analysis results, the structural safety and serviceability of the bridge are evaluated with the consideration of both the effect of the main-shock and aftershocks. As it is difficult to predict aftershocks as accurately as mainshocks, due to complicated mechanisms to induce aftershocks, the magnitudes of aftershocks are inferred using a simple magnitude evaluation formula in terms of distance, based on the statistical analysis of the aftershocks of the 2011 off the Pacific coast of Tohoku Earthquake.
