Numerical Simulation of Distortion-Induced Fatigue Effect in Steel Plate Girder Bridges

For two type of distortion-induced fatigue details at web gaps(vertical stiffener web gap and horizontal gusset plate web gap) in the steel plate girder bridges, finite element models of the straight, skewed and curved three-span continuous steel plate girder bridges were built. The out-of-plane distortion and fatigue stress of the web gap fatigue details of steel plate girder bridges with different spans, oblique angles and horizontal curve radius are investigated by numerical simulation. Parametric analysis of fatigue effect in skewed and curved bridges is carried out. The simulation results show that when under the vehicle loads, the relative out-of-plane deformation and fatigue stresses will occur at the web gap details. The relative out-of-plane distortion and the peak fatigue stress of the vertical stiffener web gap details in the straight bridge are 0.079 mm and 105.6 MPa; the relative out-of-plane distortion and the peak fatigue stress of the horizontal gusset plate web gap details in the straight bridge are 0.006 mm and 10.9 MPa. The distortion-induced fatigue effects of two types of web gap details in the skewed bridge and the curved bridge are significantly greater than that of the straight bridge, and the out-of-plane distortions are larger than that of the straight bridge. The peak fatigue stress of vertical stiffener web gap in the skewed bridge and the curved bridge are 2.4 times and 1.7 times as much as that in the straight bridge; the peak fatigue stress of horizontal gusset plate web gap in the skewed bridge and the curved bridge are 2 times and 2.9 times as much as that in the straight bridge. The relative out-of-plane deformation of the fatigue details has a strong correlation with the stress level at the fatigue details, and small relative out-of-plane deformation can cause high fatigue stress. In skewed bridges, only 0.15 mm relative out-of-plane distortion at the horizontal gusset plate web gap details can cause 250 MPa vertical bending tensile stress. Parametric analysis results show that the fatigue stress at details in skewed bridge increases with the increase of oblique angle, while the stress at fatigue details in curved bridge increases with the decrease of horizontal curve radius. In the straight bridge with a span arrangement of(45+70+45) m, the maximum tensile stresses at the vertical stiffener web gap details and the horizontal gusset plate web gap details are 105.6 MPa and 10.9 MPa. The maximum tensile stresses at the corresponding details in the skewed bridge and curved bridge with the same span are 250.5 MPa and 21.8 MPa, 176.5 MPa and 31.9 MPa, respectively, which are significantly greater than the maximum tensile stress at the corresponding details in the straight bridge with the same span.