Fatigue behaviour of CHS tubular bracings in steel bridges

The structural solution for cross girder bracings or box girder diaphragms in steel bridges is often made with tubular elements, specially efficient if compression is required for structural behaviour. The connection between the tubular elements and the girder plates is usually made with a gusset welded on a slit in the tube. The weld between the gusset and the tube at the end of the slit is a critical fatigue spot. This paper re-analyses the existing fatigue detailing recommendations and presents the results of fatigue tests carried out on CHS tubes with four different types of detail in the high cycle regime. The results were analysed with a local notch stress approach and compared with previous fatigue tests from literature. Recommendations for fatigue classification and detailing are given.