Cutting offshore monopile foundation costs

During the conference on 10 July, Scott Whyte, geotechnical consultant at Fugro and Joe Hilton, engineering manager at Sea and Land Project Engineering (SLPE) spoke on ‘How the implementation of advanced structural analyses integrated with PISA-type geotechnical analyses can realise significant project benefits and help reduce the levelised cost of energy for offshore monopile foundations’.

They outlined a case study where an integrated and collaborative workflow was adopted between structural and geotechnical focused designers to achieve reductions in project risk and the levelised cost of energy for the Seastar and Mermaid offshore wind farm substation platforms.

Design implementation

Each party implemented design analyses able to be used for monopile foundations. SLPE performed the detailed structural design using a combination of time domain and spectral dynamic analysis techniques and employed Fugro’s soil structure interaction analysis expertise to implement the recommendations from the Pile Soil Analysis (PISA) joint industry project for foundation design.

SLPE’s team developed a dynamic analysis tool capable of capturing ringing effects, due to higher order wave loading, and modelling diffraction effects, including directionality, for appurtenances as well as p-δ effects and linear buckling. This tool was used to compare DNV GL-type geotechnical modelling versus advanced soil modelling reaction curves derived between SLPE and Fugro. Fugro performed 3D finite element analysis using proprietary constitutive soil models to develop site-specific soil reaction curves for detailed structural analysis.

By Rebecca Jeffrey