Conference day 2
Wednesday, July 10th, 2019
12:00 PM How the implementation of advanced structural analyses integrated with PISA-type geotechnical analyses can realise significant project benefits and help reduce the Levelized Cost of Energy for offshore monopile foundations
A case study is presented which summarises the significant reduction in project risks and a welcomed reduction in levelized cost of energy (LCoE) realised for the Seastar and Mermaid offshore substation platform. This was achieved by adopting an integrated and collaborative workflow between structural and geotechnical focused designers, whereby each party implemented industry leading design analyses that can be employed 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 analyses expertise to implement the recommendations from the Pile Soil Analysis (PISA) (Byrne et al., 2017) joint industry project for foundation design. SLPE’s team developed a dynamic analysis tool capable of capturing ringing effects, due to high order wave loading, and modelling diffraction effects including directionality for appurtenances as well as p-δ effects and linear buckling. This comprehensive tool was used to compare DNVGL-type geotechnical modelling vs. advanced soil modelling reaction curves derived between SLPE and Fugro. Fugro performed 3D finite element analysis using proprietary soil (constitutive) models to develop site-specific soil reaction curves for detailed structural analysis according to PISA. Using such bespoke models is shown to reduce costs and schedules when compared with more standard codified approaches, significantly reducing the foundation-related risks associated with the project.