ROSAP – Ramboll Offshore Structural Analysis Programs

Dr.-Ing. Tim Fischer

Global Senior Director Wind

T: +49 40 302020-132

Ronnie Refstrup Pedersen

Senior Chief Consultant

T: +45 5161 4574

The global wind industry continues to break records for new investments and capacity however, high costs remain a major challenge to continuing the green transition.

As the fastest-growing part of the sector, the offshore wind industry still needs to find new ways to optimise the designs and the entire supply chain to reduce costs related to planning, fabrication, installation and operation. 

Optimise offshore wind foundation design and reduce capital expenditure

Ramboll’s design software ROSAP (Ramboll Offshore Structural Analysis Programs) provides indispensable tools for designing wind turbine foundations in compliance with the most recent standards and newest technologies. 

The software includes a complete package for advanced static and dynamic analyses of foundation structures, covering all phases from site assessment studies to design analysis and operational maintenance optimisation. 

In-house aerodynamic load calculations are integrated with ROSAP using generic models of the most recent turbines on the market. The generic models are combined with finite element soil models and metocean data models to simulate advanced load cases including, typhoons, earthquakes, soil liquefaction and ice structure interaction problems.

With ROSAP, Ramboll can deliver position specific designs accounting for more than 10,000 load combinations. 

Recently, Ramboll’s engineers have started using a cloud-based computing framework with up to 1000 simultaneous CPUs, significantly improving scalability and computational time by more than a factor of 10. 

Global and cross-sector application

ROSAP has been originally developed by Ramboll’s Oil & Gas division back in the 1980s. It has been used for the analysis of most jackets, topsides, offshore bridges and risers within the Danish sector of the North Sea, and for several studies in the Middle East, UK, US, and Norway.

Around 2000, Ramboll has started utilising ROSAP for the design of offshore wind turbine foundations, introducing new features for the more dynamic systems. Overall, ROSAP has been used for the design and documentation of more than 3400 individual foundation designs for wind turbines with 17 GW distributed on offshore wind farms around the world.

Designs critical for cost-effectiveness

The results from ROSAP have in some cases reduced capital expenditures compared to other competitive designs.  

Mr. Zhang Yi, project manager with the Chinese State Power Investment Cooperation, explains that the total price was a decisive factor in choosing Ramboll for the SPIC Binhai North H2 contract.

“Ramboll could supply a solution that was 20% cheaper than what the competitors had to offer and could deliver a better thought-out solution owning to its wide palette of competencies” says Zhang Yi.

Further optimising designs

It is becoming increasingly evident that measurements are a key element in lowering not only capital expenditures but also operating expenses. 

Ronnie Pedersen, Senior Chief Consultant at Ramboll, emphasises that: 

“Offshore wind turbines and foundations will be strategically monitored in the future and Ramboll has the knowhow and numerical framework to utilise the measurement data by updating the ROSAP model to a True Digital Twin, which can be used to facilitate decisions on life-time extensions or inspections. This can be used to offer new real-time insights into the health of the structure and further optimise future structural designs”.