Ultimate bearing capacity analysis of self-anchored suspension bridge with steel box girders considering local buckling

The local stability may dominate the design of a self-anchored suspension bridge with steel box girders. Due to geometric imperfections and welding residual stresses rarely considered for its ultimate bearing capacity analysis, the influences of the local buckling on the global structural behavior remain unknown. This paper presents a multi-scale finite element (FE) model for a self-anchored suspension bridge incorporating geometric imperfections and residual stresses in a steel box girder segment simulated by shell elements. Also, the pattern considering the defects in the shell FE model is validated by experiments. An extended parametric study is carried out via multi-scale FE models under various defects. Results illustrate that: (1) the effects of local buckling on the ultimate bearing capacity of the bridge is small and can be ignored if geometric imperfections and residual stresses are not considered; (2) the influences of local buckling becomes significant if geometric imperfections and residual stresses are included; and (3) ultimate bearing capacity decreases with increase of defects, with geometric imperfection being the main factor influencing the ultimate bearing capacity of the bridge. Additionally, the thickness of steel plates has significant influences on the ultimate bearing capacity of the bridge. A comparison between the EN 1993-1-5 and the FE analysis results indicates that the former is conservative. This study provides useful insights for analyzing and designing local buckling from the perspective of steel bridge system.