Parametric analysis of rib distortion in orthotropic steel decks

In orthotropic steel decks, the trapezoidal section is one of the most widely adopted geometries for ribs. However, due to the existence of cut-outs in the crossbeams, the torsional rigidity of the ribs is fundamentally reduced by distortion, especially when the load was at mid-span and eccentric from the axis of the rib. The rib distortion causes high stress concentrations at the rib-to-crossbeam joint, which had become one of the most vulnerable details to fatigue. In this paper, the influence of 5 classical design parameters on the distortional behavior was analyzed based on finite element analysis. A refined finite element model of an orthotropic steel deck specimen (8.2 m x 4.1 m) was developed, adopting the sub-model analysis technique and the hot spot stress approach. Research results revealed that the distortional stress of rib-to-crossbeam joint was negatively correlated with the thickness of rib, positively correlated with the spacing of rib, the weld length of rib-to-crossbeam joint and the spacing of crossbeam. The height of crossbeam did not have obvious influence on distortional behavior. Approaches e.g. increasing the thickness of rib or decreasing the spacing of crossbeam would increase the stress of rib-to-deck joint while reducing the distortional stress.