Structural health monitoring (SHM)

Structural health monitoring measurements are combined in a single, integrated system, that means structural response can be interpreted alongside geotechnical and environmental conditions, rather than assessed in isolation. NGI is uniquely placed to support your offshore wind project demands. We consider the following factors;

Environment

• External factors, such as wind and waves
• Environmental conditions inside the structure (e.g; gases)

Structure

• Structural strain and stress
• Dynamic motion and vibration
• Inclination and other measurands

Foundation connection

• Deformation at grouted connections
• Residual bolt tension in bolted joints
• Load distribution over the structure
• Corrosion rate and cathodic protection
• Marine growth and other external factors over time

Below the seabed

• Soil model and spring performance
• Stress in the structure below the mudline
• Settlement
• Seabed scour
• Structural health following impact driving

Our approach to monitoring in offshore wind

“Prototypes are our standard.”
Offshore wind foundations are rarely standard: soil conditions, structure type, and load paths differ from site to site. NGI's monitoring designs start from the foundation's actual soil-structure interaction rather than a generic instrumentation package — which is why most of our systems are engineered for the specific structure rather than supplied off the shelf. System supply is followed up from concept through to installation and commissioning. In-house engineering innovation for tricky-to-measure applications is underpinned with tried and tested elements, to help keep costs viable and delivery schedules on track.

An independent service provider
Many structural health monitoring providers sell their own sensor hardware or software platform. NGI does not. We specify and integrate instrumentation from established suppliers based on what performs best for the specific structure and site, rather than fitting a client's foundation to a fixed product line.

Monitoring data is used to validate design assumptions against actual site conditions, inform O&M decisions before problems become failures, and build the evidence base needed to support lifetime extension applications. Data can be delivered through platforms such as NGI Live, giving clients direct access to their own structural and geotechnical data with other site investigation results.

• Track record — offshore instrumentation experience dating back to the 1970s
• Standards — instrumentation specified with reference to DNV recommended practice and relevant ISO standards
• Independence — no proprietary sensor line; systems are specified around the structure, not a fixed product
• Collaborative approach – Our colleagues are regular speakers at technical conferences in the industry, sharing research and results

Research driven

NGI participates in many industry-focussed research groups, applying the results to real-world offshore wind projects.

• RedWin. REDucing cost in offshore WINd by integrated structural and geotechnical design
• ProWind. ProWind aims to facilitate research, innovation, and sustainability in offshore wind foundation systems. It enables physical testing at multiple scales, from soil behavior under varying loads at the element level (in the laboratory) to large-scale testing of new technology concepts and models in the field
• WindRise (WINDRISE is an innovation project that will bring together leading Norwegian stakeholders in the value chain from design, production, transport and installation of bottom-fixed substructures for offshore wind to enable scaling up and accelerated distribution of large offshore wind farms
• PIGS The Joint Industry Project (JIP) Piling in Glauconitic Sand (PIGS) aims to address the uncertainties arising from the behavior of such soils around piles
• TailWind NGI coordinates this four-year EU project focusing on mooring lines and anchors for floating offshore wind turbines. The project will develop further these technologies identifying opportunities for cost and environmental impact reduction
• OASIS NGI jointly organised the first International Seminar on Offshore Anchoring Systems. The seminar was established to meet the growing need for a dedicated forum on anchoring systems for floating offshore wind.

From collaboration to insight

NGI takes a collaborative approach. A monitoring contract typically follows the same sequence, from award through to years of operational data.

• Define: Monitoring objectives and what needs to be measured.
• Design: Instrumentation strategy, sensor selection and system design with in-house testing.
• Install: Expert offshore installation with minimal disruption to operations.
• Monitor: Continuous data acquisition and quality assurance, with a good understanding, for example, of likely survival rate for sensors in monopiles.
• Interpret: Data analysis, insight, and decision support that drives action.

Bespoke monitoring solutions for monopiles and jackets

NGI understands the need to innovate to keep costs down, schedules on-track, and (above all) deliver quality data. Examples of innovation in offshore wind foundation projects include;

• NGI designed, built, and owns a DNV-certified fast magnetic scaffolding system meaning we work quickly inside the monopile in the yard with minimal disruption, and no rollers needed
• NGI designed a suspended rope cabling method to reduce the risk of impact on sensor cables inside monopiles
• NGI first installed a protective patch to protect strain gauges and temperature sensors subsoil back in 2016, and has been doing so ever since
• NGI developed a protective, sliding sheath to protect subsoil cables from pile-driving shock and impact damage beneath the soil line
• NGI has a large test laboratory and in-house workshops to design and deliver bespoke structural health monitoring systems for offshore wind, based at our Ullevål headquarters, in Oslo.

Why NGI?

There is a total of 1660 turbines (~19.7 GW of power) benefitting from NGIs structural health monitoring services, although, thanks to digital twinning and advanced modelling, not every turbine needs sensors below the mudline. NGI also provides geotechnical services to very many more of the world’s offshore wind farms, either direct to the developer, or with the designers and supply chain. We are interested in helping to reduce the cost of energy, and bring foundation innovations to market quicker, by supporting your testing and monitoring campaigns. 

NGI's field testing and offshore instrumentation department has 14 specialist staff, working alongside an 18-strong monitoring department and drawing on the wider geotechnical engineering capability of some 450 NGI employees. We have offices in Oslo, London and Perth with well-qualified and experienced geotechnical staff to support your work.  Sample CVs of our project team are available on request.

Want to know more? 

Contact information below.