Abstract：A numerical procedure for shakedown analysis is presented，in which the elasto-plastic finite element method is combined with Melan's theorem of shakedown analyses. The proposed method is applied to evaluate both ultimate loads and shakedown loads of offshore platform foundations. Based on numerical results computed for different load modes，ultimate loads and shakedown loads of offshore platform foundation are compared. The ultimate loads and shakedown loads for different combinations of horizontal component and vertical component as well as moment constitute an envelope in the load space. Such envelope diagrams can be employed to rationally evaluate the dynamic stability of offshore platform foundations under complex varied loading pattern.
