COUNTERMEASURE EFFECT OF UHPFRC OVERLAY ON FATIGUE CRACKS PROPAGATING FROM U-RIB WELDS OF ORTHOTROPIC STEEL DECKS

Abstract

 Over the last decade, fatigue cracks have been observed at welded joints between U-ribs and deck plates in many orthotropic steel deck bridges in Japan. Among the cracks, this paper focuses on fatigue cracks that initiate from a weld root of rib-to-deck welded joints and propagate to a deck plate. This study examines the effect of countermeasure with overlaying Ultra-High Performance Fibre Reinforced cement-based Composites (UHPFRC) on steel decks with cracks from U-rib welds, and confirms the fatigue durability of this countermeasure method. Specifically, the suppressing effect on crack propagation and the fatigue durability of UHPFRC itself and the interface between UHPFRC and the deck plate were confirmed by a wheel running test and finite element analysis. As a result, it was clarified that this countermeasure has a positive effect to retard further crack propagation compared with a countermeasure with overlaying steel fiber reinforced concrete which is generally adopted. In addition, it was revealed that this countermeasure has enough fatigue durability.