Influence of local geometric parameters on fatigue performance of orthotropic steel deck

Fatigue has become critical issue for bridge with orthotropic steel deck. Number of stress cycle and equivalent stress amplitude were adopted as two investigated fatigue effects. As presented from fatigue monitoring comparison of two series-lined bridges, three local geometric parameters of steel box girder have significant influence on fatigue performance of two welded joints. They are thickness of longitudinal ribs (T (r)), longitudinal spacing of transverse floor plate (S (c)) and longitudinal truss (L (T)). Fatigue analytical models were created for parametric study of fatigue effects under wheel load. Consequently, three local parameters have exhibited insignificant influence on number of stress cycle. Compared with T (r) and S (c), configuration of L (T) has brought about foremost effect on the equivalent stress amplitude. For equivalent stress amplitude of rib-to-deck and rib-to-rib welded joints, the influence regions of L (T) are respectively longitudinal strap and quadrate with the geometric length of 600 mm. Enough attention ought to be paid for local stiffen structure on fatigue performance of orthotropic steel deck in fatigue design and monitoring.