A Consistent, Rigorous and Super-Fast Monopile Design Approach-Paper

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The paper presents SUMO (SUperfast MOnopile design), an automated approach for designing monopile foundations for offshore wind turbines. It combines NGI’s cyclic soil-accumulation method with INFIDEP, a fast 3D finite-element analysis program, and a procedure for calibrating soil-reaction springs for structural models.<br /><br />SUMO evaluates three design limit states. The Serviceability Limit State (SLS) checks that accumulated permanent pile rotation over the turbine’s lifetime remains acceptable. The Ultimate Limit State (ULS) checks pile displacement under maximum loads. The Fatigue Limit State (FLS) evaluates foundation stiffness and system eigenfrequency, and supports fatigue analysis. Cyclic laboratory-test data and load histories are used to derive representative soil responses for these analyses.<br /><br />A Python script automates load and soil-data processing, geometry screening, finite-element analyses, and spring calibration. INFIDEP’s predictions were consistent with pile-test results and comparable with PLAXIS, while analyses took roughly 30–60 seconds. In a comparison with the more advanced UDCAM method, SUMO predicted the cyclic response well, though it slightly overestimated displacement. The resulting site-specific springs reproduced pile-head response and internal forces.<br /><br />The approach enables efficient, potentially wind-farm-wide design and makes it practical to assess uncertainties in geotechnical loading. Important simplifications include assumptions in the cyclic stress-history treatment and the use of undrained behavior during peak loading. The authors note that average-load drainage effects in sand should be reflected in cyclic soil testing. Overall, SUMO offers a streamlined way to account for layered soils and cyclic loading while delivering design geometries and spring inputs for structural analysis.

Keywords

monopile design

offshore wind turbines

cyclic soil loading

finite element analysis

soil-reaction springs

serviceability limit state

ultimate limit state

fatigue limit state

INFIDEP

geotechnical design automation