PISA / PiCASO Projects: Design of Offshore Wind Turbine Monopiles-PPT Presentation

PPT Presentation

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The presentation reviews the development of design methods for offshore wind turbine monopiles, focusing on monotonic and cyclic lateral loading. The PISA project (2013–2018) combined advanced numerical modelling with 28 field pile tests at two sites to develop and validate simplified engineering models. These methods predict pile response more accurately than traditional p–y approaches and are now widely used to optimise monopile designs.<br /><br />The ongoing PICASO collaboration between Oxford and Ørsted extends this work to cyclic loading, a growing design challenge as turbines become larger and are installed in deeper water. Cyclic models must represent hysteresis, accumulated displacement (ratcheting), changing stiffness, and post-cycling capacity under irregular, pseudo-random loads. Monotonic response remains essential to cyclic analysis, and time-domain calculations are important.<br /><br />PICASO is developing a design framework grounded in advanced plasticity theory, including the Hyperplastic Accelerated Ratcheting Model (HARM). The framework addresses post-cyclic monotonic response, displacements under random loading, and loading-rate effects. Field testing at Cowden and Cuxhaven includes monotonic, cyclic, large-amplitude, and multidirectional loading. The methods have been demonstrated on 1.22 m and 2.50 m diameter scale monopiles in stiff clay and medium-dense silica sand.<br /><br />The presentation concludes that evidence-based methods and testing across scales are central to improving monopile design, with cyclic behaviour remaining a key challenge for future offshore wind development.

Keywords

offshore wind turbines

monopile design

cyclic loading

monotonic loading

PISA project

PICASO collaboration

lateral loading

ratcheting

plasticity theory

hyperplastic accelerated ratcheting model