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DNV-OS-C105 Structural Design of TLPS (LRFD method)

Sec.2: Structural Categorisation, Material Selection and Inspection Principles

B: Structural Categorisation

Sec.2
B. Structural Categorisation

Sec.2
B 100   General

Special category

1. External shell structure in way of intersections of columns, topside deck, lower hull and tendon porch etc.
2. "Through" material used at connections of columns, topside decks and lower hull which are designed to provide proper alignment and adequate load transfer.
3. External brackets, portions of bulkheads, and frames which are designed to receive concentrated loads at intersections of major structural members.
4. Tendon interfaces with the foundation and the TLP hull.
5. Tendon and tendon connectors.
6. Highly utilized areas supporting crane pedestals, flare booms etc.

Guidance note:
Highly stressed areas are normally considered to be areas utilized more than 85% of the allowable yield capacity.

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Primary category

1. External shell structure of columns, lower and upper hulls.
2. Bulkheads, decks, stiffeners and girders which provide local reinforcement or continuity of structure in way of intersections, except areas where the structure is considered for special application.
3. Truss rows and horizontal diagonal bracings on the deck.
4. Main support structure of heavy substructures and equipment, e.g. cranes, life boat platform, thruster foundation and helicopter deck.

Secondary category

1. Bulkheads, stiffeners, flats or decks and girders in columns, decks and lower hulls, which are not considered as primary or special application.
2. Horizontal braces and members on the decks.
3. Well-bay trusses and reaming members.
4. Other structures not categorised as special or primary.

Fig. 1   Principles of the extent of structural categorisation special and inspection categories at tendon foundation

_{* Special if damaged condition is not fulfilled.}
Fig. 2   Example of tendon connections