Abstract: The main objective of this DPhil is to translate the scientific developments and modelling findings from field tests to a recommended design approach tackling the effects of cyclic loading across soil types, layers, and pile designs. The approach needs to be linked to a general new geotechnical design process of monopile foundations covering all three limit states: FLS, ULS and SLS. The DPhil will address the accuracy and sensitivity of the new design method pending changes to the chosen monotonic backbone, loading biases & loading magnitudes. Further, the impact of loading history will be addressed. Continuing the work within the hyperplasticity framework, a clear division between implicit and explicit methods used will be addressed. An attempt to optimize the usability of the approach will be performed to enable the usage of HARM in the optimization loop and not just in the monopile design validation procedure.