We started by collecting and reviewing all existing structural documentation for DolWin gamma, including layout plans, topside drawings, and previous analysis results.
Initial review
Upgrade of offshore HVDC platform
Structural reassessment for DolWin gamma MLQ installation
Client
TenneT
Year
2025
Platform type
Offshore Platfom DolWin gamma (HVDC offshore platform)
Class
Eurocode, DIN 18088
SOW
Structural Analysis for Modular Living Quarters (TLQ) Installation
-
13000kN
of load evaluated
-
45.95mm
deflection
-
96%
utilization
Client context
TenneT, the operator of the HVDC offshore platform DolWin gamma of the offshore grid connection DolWin5, planned to modify the configuration of their Modular Living Quarters (MLQ) by changing the number of future accommodation containers onboard. The MLQs, including associated water treatment systems, had to be reinstalled on an existing grillage structure.
With regulatory requirements shifting from DNV standards to EUROCODE and DIN 18088, TenneT needed a new structural assessment to ensure compliance and safety under the updated design code regime.
The Challenge
The existing grillage was originally designed under DNV standards and had been used to support a previous TLQ configuration.
The challenge was to verify whether this existing structure, along with the underlying deck, could safely support the new arrangement of containers using the updated Eurocode-based design standards.
This involved detailed Finite Element Modelling (FEM) and evaluation of stress, displacement, buckling, and environmental load conditions.
BRIEF
The work to be done
project phases
The work to be done GLO Marine was tasked with performing a comprehensive structural analysis of the topside and grillage structure to validate the installation of the revised TLQ setup.
The project included modeling the grillage, applying realistic boundary conditions and loads (static, live, wind, snow, and ice), and verifying the system against updated certification requirements.
The evaluation would support certifiable documentation required by Lloyd’s Register.
PROJECT SOLUTION
Involvement of GLOMARINE throughout the project stages
01
02
Model development
We created a detailed Finite Element Model (FEM) of the topside deck area from Frame 46 to Frame 114 and incorporated the full geometry of the existing grillage, containers, and staircases.
03
Load identification and application
We calculated and applied various loads:
- Permanent loads: Weight of grillage, MLQ containers, stair containers, and water treatment containers.
- Variable loads: Life loads inside the containers and staircases, deck live loads, and passageway loads.
- Environmental loads: Wind, snow (drifted and undrafted), and ice loads based on site-specific metocean data.
04
Structural evaluation
- Stress (Von Mises): Maximum recorded vs. allowable (Utilization 96%). For the grillage we identified some high stressed areas caused by the increased loads as the factors of the Eurocode are more restrictive. We proposed solutions.
- Displacement: Maximum vertical displacement.
- Buckling: All critical buckling zones were within acceptable safety margins.
05
Friction & load capacity check
- Evaluated friction coefficient requirement for rubber mats under grillage to resist wind suction.
- Verified deck load bearing capacity for general areas, for designated laydown zones.
END OF DELIVERY
The Outcomes
FINAL RESULTS
We delivered a comprehensive structural report confirming the adequacy of the deck and grillage under the new MLQ configuration.
The FEM analysis demonstrated compliance with EUROCODE and DIN 18088 standards, with only minor local exceedances in the platform structure found to be non-critical and solutions to improve the grillage structure for the rule-updated loads.
The study enabled TenneT to proceed confidently with MLQ reconfiguration and supported the documentation needed for class approval.
The outcome: a verified, certifiable, and regulation-compliant solution for extending the service life and operational capability of the accommodation infrastructure.