PICASO: Cyclic Lateral Loading of Offshore Wind Turbine Monopiles-Paper

Paper

Pdf Summary

PICASO (Pile Cyclic Analysis: Oxford and Ørsted) develops practical methods for designing offshore wind turbine monopile foundations under repeated wind, wave and operational loads. It builds on the PISA project, which established validated methods for monopiles under monotonic loading and showed that improved design can reduce foundation material costs by up to 30%.<br /><br />Cyclic loads can cause permanent displacement to accumulate over time, affecting turbine serviceability and fatigue performance. PICASO combines PISA’s design approach with the Hyperplastic Accelerated Ratcheting Model (HARM), which represents cyclic hysteresis, ratcheting, stiffness changes and loading-rate effects. The project focuses particularly on relatively short, rigid piles subjected to realistic, variable-amplitude and multidirectional loading.<br /><br />Five work packages support the development and application of the methods: advanced numerical modelling, including data-driven tools; laboratory and model-scale testing to calibrate design inputs; theoretical development of HARM; medium-scale field tests to validate predictions; and application to turbine- and wind-farm-scale design optimisation. The field programme includes different loading rates, cycle amplitudes and directions, with heavily instrumented piles at two sites.<br /><br />By integrating experimental evidence and computational models, PICASO aims to make cyclic pile design more reliable and less conservative, extend PISA methods to a wider range of ground conditions, and embed the resulting tools in engineering practice. Ultimately, better prediction of long-term foundation behaviour should enable robust, cost-effective monopiles and help lower the cost of offshore wind energy.

Keywords

PICASO

offshore wind

monopile foundations

cyclic loading

PISA project

foundation design

ratcheting model

HARM

wind turbine

load optimization