Objectives  Ships and offshore platforms serve in the harsh sea environment for a long time. Cracks and pitting corrosion will occur in such a structure and the damage will affect its ultimate strength.

  Methods  To investigate the influence of cracks and pitting corrosion on ultimate bearing capacity, the ultimate strength of a structure under axial compression is studied by using a nonlinear finite element. The mesh size of a stiffened plate with cracks and pitting corrosion is first discussed. Then the influence of the relative positions of cracks and pitting corrosion, number of corrosion points and crack length impact on the residual ultimate strength of damaged stiffened plates is discussed via a series of calculations.

  Results  The results indicate that the increase in crack length and pitting corrosion significantly decreases the ultimate strength of a stiffened plate.

  Conclusions  This provides a useful reference for designing and maintaining ships and offshore structures in their life cycles.