Abstract
Kita Bisan-Seto Bridge is a suspension bridge with stiffened truss girder, and has 990m center span. Its highway section is composed with orthotropic steel decks (OSD). There are a large number of steel plates that are fillet-welded to bottom flanges of transverse ribs of the OSD. The plates are for hanging scaffoldings in maintenance works. It was predicted that passing vehicles cause high stress in the bottom flanges, while this type of weld joint is classified in relatively low fatigue strength category. The authors performed 3-day stress measurement in order to study fatigue conditions. The fatigue life is evaluated as about 100 years, but it can be a half of the evaluation because of welding quality and accuracy of evaluation method.
