Engineering Services

NIRAS offers engineering expertise and design consultancy from the early conceptual phase through to final detailed design.

Offshore wind projects are complex and long running. Strong engineering competencies are therefore required in all project phases to ensure the best and most appropriate project development throughout all project phases.

We provide contract and package management services for our clients as well as technical on-site supervision during cable, foundation and WTG installation and commissioning phases. Our experienced engineers provide technical assistance in areas such as quality management, document review, interface management, health and safety and environmental management. Our approach to design combines extensive in-house expertise in hydrodynamics, geotechnics and structural engineering. Using our extensive experience and innovative approaches, we can identify the best foundation type for a specific locations and purposes.

Expertise in hydrodynamics, geotechnics and structural engineering

Our approach combines extensive in-house expertise in hydrodynamics, geotechnics and structural engineering. Using our extensive experience and innovative approaches, we can identify the best foundation type for a specific locations and purposes. We use in-house engineering design software which we continuously develop and test.

Examples of innovative projects in which NIRAS has participated

NIRAS offers development of detailed design of foundations for offshore wind farms where weather conditions are extreme. We can furthermore introduce damping systems with the aim to reduce fatigue and increase the life span of steel monopoles. In addition, we design monopiles with bolted connections between monopile and transition piece as well as integrated monopiles, where the transition piece is omitted. We ensure that both designs are combined with an optimised installation and operation procedure.

We conduct parametric studies of various floater concepts, where the knowledge obtained can be used to consider different floater concepts in early design phase where choice of concept has significant impact on the cost.

NIRAS is also a front runner in provision of hydrodynamic loads to a detailed concrete foundation design based on CFD calculations, certified by a leading certification company. We solve challenges within such tasks regarding verification of the model, through extraction of relevant results and inclusion of influence of the irregularity of the waves.

NIRAS furthermore possess experience within development of Design Basis, including design briefs, and performance of detailed design which includes:

Geotechnical data interpretation and design profiles per foundation locations
Natural frequency of WTG systems and OHVS system
Extreme events
Fatigue (installation and operational)
FEM analysis of grouted connection
Corrosion protection (surface protection, cathodic protection)
Scour protection
Ship impact
Design of primary structures
Design of secondary structures
Design of provisional structures
Design of elastomeric bearing system (provisional solution in case the vertical bearing capacity of the grouted connection should fail)
Installation
Dismantling
Fabrication
Operation and maintenance
Quality control (fabrication and installation)

We are also experienced in developing alternative detailed designs with the purpose of minimising installation risks. This process includes:

Development of a new design with elastomeric bearings, resting on the TP and the MP top edge, and serving as provisional back-up solution in case the grouted connection should fail.
Design of an epoxy containment ring (ECR) to be established below traditional grout zone. The purpose of the ECR is to minimise the risk of the crushed grout being washed away. Once the epoxy has hardened, a traditional grout is injected on top of the ECR. In order to verify the flow pattern of the epoxy and that the epoxy has the required mechanical properties after curing, a full scale test of the epoxy injection is performed and evaluated.

Geotechnics

NIRAS carries out a variety of research & development activities covering both theoretical and experimental geotechnics.

Soil Models at a Theoretical Level and in Pratical Tests

NIRAS carries out a variety of research & development activities. A selection of activities is listed below.

Scour: Theoretical developments and testing.
Suction bucket: Suction bucket installation and extraction – NIRAS' developed methods and carried out the geotechnical analyses required for an oil and gas RAT (riser access tower) installation in Southern North Sea .
Soil models: Pore water modelling, liquefaction with university partners.
Soil tests: Soil test are performed with university partners.
Soil forces: (p-y) curves using In-house computer programmes.
Pile driving: Tests are performed.

Conductor Design

Development of soil models for implementation in NIRAS structural analysis method for offshore well conductors and casing systems.

Subsea Tie-In Spool and Pipeline Design

Development of soil models for expansion analysis, upheaval buckling analysis and riser deflection analysis.

Hydrodynamics

NIRAS' Research & Development of theoretical & experimental hydrodynamics.

Activities of Hydrodynamics

NIRAS carries out a variety of research & development activities covering both theoretical and experimental hydrodynamics. Some projects carried out with partners and within recognized research programs. A selection of activities is listed below.

VIV: NIRAS has its in-house unique software for calculation of cross-flow and in-line vortex shedding respons on slender structures. NIRAS has participated in various experimental projects including methods which are verified against scale tests.

Shielding: NIRAS developed its own method for calculation of shielding effects between slender offshore structures such as conductors, risers, jacket legs/braces, caissons etc. The method is based on experiments and potential theory. The methods have been used to optimize the load calculation on a large number of offshore platforms in Danish and Norwegian waters.

AWARE: Abnormal Wave Assessment and Risk Evaluation. NIRAS takes a major role in the ongoing project for improvement of hydrodynamic load calculation for offshore structures, including the response from abnormal breaking ocean waves.

Tests: Scale tests preparation for breaking wave, wind and and structural response tests in Danish waters with an offshore test station North of Anholt and in onshore test center.

Full scale wave measurements: NIRAS installed tripod wave measurement structures for laser doppler measurement of wave particle velocities in the water column, North Sea at 40 meter water depth.

NIRAS: Development of flow field around special subsea structures, such as large oil and gas/wind gravity base structures.

Wave slamming: Development of theory and computer code for load generation and fatigue calculation of 3D wave slamming occurence at structural brace members in North Sea jacket structures.