Study on Improvement of Fatigue Strength of Welded Structures by New Functional Structural Steel Plates

Abstract

Fatigue failures occur in bridges because of their long term use and the severe traffic load conditions. Attempts that have been made to avoid have focussed on improvements to the design and fabrication processes, but improving the fatigue strength of the base plates has been regarded as impossible. On the other hand, new functional structural steel plates were developed in 2001 in Japan. This fatigue resistant steel has high fatigue strength at welded joints and also has high resistance against fatigue crack propagation in the base plates. It has already been used widely for ship fabrication in Japan. Therefore the applicability such the steel plates for bridges was examined in this study. Beam to column connections, joints between deck plate and U-rib and steel plate girders were selected as suitable applications. The results of this study on their applicability to each type of member are reported in this paper. In addition, an example of the application to a steel plate girder bridge in Japan is introduced.