Because of simple structure and convenient manufacture, steel plate girder bridges are widely used in medium and small-span bridges. On account of the vertical deflection difference existing in adjacent main beams of steel plate girder bridges under vehicle loads, significant out-of-plane distortion exists in the web gap, and fatigue cracks are easy to appear under cyclic vehicle loads. A simple supported steel plate girder bridge based on an actual highway bridge design is used to investigate the fatigue response due to out-of-plane distortion. Finite element software is used to build finite element model of steel plate girder bridges and local sub-model of the web gap, and it is used to explore distribution regularities and out-of-plane distortion characteristics at the web gap of main beam under vehicle loads. Three finite element models of bridges with different flat curve radius are established, and parameters such as the size of the web gap, the thickness of the bridge deck, and the thickness of the stiffeners are changed. Two different lane loads are considered to analysis influence factors of distortion-induced fatigue response at the web gap of steel girder bridges. Results show that there are significant fatigue stresses at the web gap of steel plate girder bridges under vehicle loads, and stresses are normally distributed along the stiffener, with the greatest stress at the weld toe. The fatigue stress of the web gap decreases with the increase of the web gap, flat curve radius, stiffeners thickness and bridge deck thickness. The relative out-of-plane distortion of the web gap is positively correlated with the web gap and the flat curve radius, and has little effect on the thickness of ribbed stiffener and bridge deck.
ACKNOWLEDGEMENT
The authors gratefully acknowledge the financial support provided by National Natural Science Foundation of China (52308160)， Fundamental Research Funds for the Central Universities (HEU 3072024JJ2703)， Global High-level Partnership Building Project (HEU GK0000020127), and Guangdong Zhuhai LNG Expansion Program Phase II EPC Project Excellence Initiative Program (China National Offshore Oil Corporation) (Grant No. Z2023LGENT1210).