Site-specific ground motion simulation and seismic response analysis at the proposed bridge sites within the city of Addis Ababa, Ethiopia

Abstract

In this study synthetic ground motion time histories have been generated at rock sites simulating earthquakes of moment magnitudes 6.8, 6.0 and 5.2 and epicentral distances of 25, 50, 80, 120 and 200 km. Applying these rock time histories as input motions at the base of the soil columns determined using surface seismics, a one-dimensional, equivalent-linear analysis was used to propagate the input motions through the soil columns to determine the ground motions at the ground surface. The goal is to determine the seismic responses of the sites chosen for bridge construction in the framework of the Addis Ababa City Ring Road Project. The computed acceleration time histories, response spectra and amplification spectra will be most useful for design engineers.