Study on Bearing Capacity of H-Shaped Steel Used in Offshore Structure Considering Local Random Pitting Damage

Corrosion damage is an important factor causing structural failure in offshore structures. In order to study the effect of local corrosion on the bearing property of H-shaped steel used in offshore structures, the rig substructure on an offshore platform was taken as the research object. Considering both local damage and the overall structural characteristics of the substructure, the main load-bearing H-shaped steel component was determined through testing. Based on the macroscopic characterization analysis of random pitting corrosion such as morphology, depth, diameter and location, a random pitting damage model was established by combining a regular cylindrical pit model with a MATLAB-based random number generation method. The influence of random pitting position on the bearing property of H-shaped steel is obtained by the simplified beam model and the multi-scale model embedded into the global substructure system respectively. The results show that pitting located at the flange end region produces the most severe stress concentration and results in the greatest degradation in bearing capacity, and corrosion on the upper flange leads to higher equivalent stress levels than that on the lower flange. The research results can provide some reference value for structural safety performance assessment.