A modified undrained elastic-plastic model considering the cyclic degradation of clay soil is proposed. Based on this model

a simplified analysis procedure based on shear displacement method is presented. Numerical simulations for axial bearing capacity of single pile are conducted by commercially available finite element software at different cyclic load levels. The results calculated by this simplified analysis have a good consistency and effectiveness with the results from finite element analysis. The axial bearing capacity of single pile will be degraded after resisting cyclic loading

and the degradation will be greater as the increase of cyclic loading levels. As an example

the axial bearing capacities of pile foundation of an offshore wind farm are studied with the application of the proposed simplified analysis method. The proposed simplified calculation method will serve as a useful tool for engineering design.