AbstractUnder excessive plastic deformations, pitting corrosion can accelerate ductile fracture initiation in steel structures. For an accurate numerical prediction of ductile fracture in corrosion pits, a micromechanical fracture criterion along with a fine three-dimensional solid meshing is required. Previous studies on this topic are limited to simple plates; however, for a more detailed component, e.g., steel beam-to-column joint, implementing the pit geometry on the global model of the joint is challenging in terms of meshing and computational time. In this paper, two-level numerical modeling was employed to reduce the complexity of the problem. In this technique, submodels with refined mesh are used to perform micromechanical simulations and assess the ductility degradation of joints. For a case study joint, the pits near the edge of the web and flange plates were found to be the most critical and they can reduce the fracture initiation displacement of the joint by about 25%. On the other hand, the pits located on the edges of plates or far from the edges caused a negligible reduction in the fracture initiation displacement of the joint. These results suggest two-level numerical modeling as a viable technique to facilitate micromechanical simulation of pitting corrosion in corroded steel joints.