DAMAGE MECHANISM OF THE NAKAGAWA WATER-PIPE BRIDGE DURING THE 2011 TOHOKU EARTHQUAKE

Abstract

 Several water-pipe bridges had damage during the 2011 off the Pacific coast of Tohoku earthquake in March 2011. This study focuses on the largest one of the damaged bridges, called the Nakagawa water-pipe bridge. This bridge is the large cable-stayed truss bridge of two parallel pipelines with 900 mm in diameter, located in Mito City, Ibaraki Prefecture. The expansion joints between the cable-stayed bridge and side single truss bridge was pulled out and rotated and the bearing were removed. This study attempts to make clear its damage mechanism by microtremor observation and the three-dimensional FEM analysis. In spite of moderate seismic ground motion at the resonant frequency at the site, the bearing damage could be simulated by the analysis as the actual damage.