Investigation of the Tsujun Bridge damage mechanism during the 2016 Kumamoto earthquake

Abstract

Tsujun Bridge, a stone arch bridge, suffered slight damage during the 2016 Kumamoto earthquake. In this study, a microtremor observation was conducted, the natural frequencies of the bridge were estimated, and the horizontal-to-vertical (H/V) spectral ratios at Tsujun Bridge and at a strong-motion observation site were calculated. The ground motion for Tsujun Bridge was estimated based on H/V spectral ratios, and a numerical model was created based on the observed natural frequencies. The seismic response of the numerical model was simulated using the refined distinct-element method, and the damage mechanism during the Kumamoto earthquake was investigated.