Development of retrofitting method against fatigue cracks in orthotropic steel deck stiffened by trough ribs

摘要

Orthotropic steel deck is suitable for a long span bridge because of its light weight. And closed section ribs, we call "trough ribs", are used for orthotropic steel deck in Honshu-Shikoku Bridges because of excellent bending capacity with less number of weld lines and less areas of anti-corrosion. In orthotropic steel decks stiffened by trough ribs, fatigue cracks resulting from large vehicles have been observed with the increase of the service years. The cracks found in trough-deck welds are bead-penetrating type. Several retrofitting methods have been studied for these bead-penetrating cracks so far. However, effective method that is applicable from the underside of the deck is still under development. In this paper, development of a retrofitting method using Thread Rolling Screw from the underside of the deck, fatigue test results and application test in an in-service bridge are described.