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WP 5 DOME and RISER-TUBE ASSESMENT (STRUCTURAL BEHAVIOUR) Solver: ABAQUS standard 6.6.4 March 2007

WP 5 DOME and RISER-TUBE ASSESMENT (STRUCTURAL BEHAVIOUR) Solver: ABAQUS standard 6.6.4 March 2007. DOME DETAILS: Number of cables: 12. Material: Dyneema. Young modulus: 65130 MPa. Diameter: 98 mm. Section: 4970 mm2. Minimum Break Load: 5838 kN. FE model.

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WP 5 DOME and RISER-TUBE ASSESMENT (STRUCTURAL BEHAVIOUR) Solver: ABAQUS standard 6.6.4 March 2007

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  1. WP 5 DOME and RISER-TUBE ASSESMENT (STRUCTURAL BEHAVIOUR) Solver: ABAQUS standard 6.6.4 March 2007

  2. DOME DETAILS: • Number of cables: 12. • Material: Dyneema. • Young modulus: 65130 MPa. • Diameter: 98 mm. • Section: 4970 mm2. • Minimum Break Load: 5838 kN. • FE model. Boundary conditions: x, y, z displacements constrained. Truss elements (only axial stiffness) Rigid ring.

  3. SCENARIO 1: - Vertical load (1000 or 2000 Tn) F vertical Linear behaviour is verified

  4. A’ A Lateral reaction at the top of the dome due to the current over riser tube: 1,182·106 N. • SCENARIO 2: • Vertical load (1000 or 2000 Tn) • + • Lateral load 118 Tn. F vertical F lateral Non linear behaviour is observed

  5. SCENARIO 3: • Vertical load (1000 or 2000 Tn) • + • Lateral load 118 Tn. • + • Pressure over dome due to current. Integrated by 5 concentrated loads in each cable. Every 20 meters height. F vertical F lateral

  6. Based on the small differences showed beside for the two different speeds analysed, the same pressure distribution (Cp-values) has been used to obtain the pressure at different speeds. P = 0.5 * Cp * density * vel^2

  7. SCENARIO 3 (1000 Tn): ANCHORING LOADS

  8. SCENARIO 3 (2000 Tn): ANCHORING LOADS

  9. SCENARIO 3 (2000 Tn – speed 0.6 m/s): CABLE STRESSES

  10. SCENARIO 3 (1000 Tn): CABLE STRESSES

  11. SCENARIO 3 (2000 Tn): CABLE STRESSES

  12. SCENARIO 3. VERTICAL DISPLACEMENT OF THE RIGID RING. Ring displacement

  13. SCENARIO 3. HORIZONTAL DISPLACEMENT OF THE RIGID RING. Ring displacement

  14. RISER TUBE DETAILS: • Detailed FE model of riser tube between two rings (50m). • Cables: • Number: 6. • Material: Dyneema. • Diameter: 98 mm. • Young modulus: 65190 MPa. • Section: 4970 mm2. • Minimum Break Load: 5838 kN. • Pipe: • Outer diameter: 2m. • Wall thickness: 76.9mm (77mm). • Material: PE100. • Modulus of elasticity at time cero: 1050MPa. • Modulus of elasticity after 50 years: 200MPa. • Design stress at time cero: 9.4MPa. • Design stress after 50 years: 6.3 MPa.

  15. Boundary Conditions and Loads: • Vertical load: (1000Tn and 2000Tn). • Pressure map around the tube (1,29 m/s). • P = 0.5 * Cp * density * vel^2

  16. RISER TUBE DETAILS: • Hypothesis: • Detailed FE model of riser tube between two rings (50m). • Rigid and fixed rings. • Only lateral forces transmitted between cables and tube. • (vertical pre-tension is not transmitted to the PE-pipe). • At time 0: • Maximum lateral displacement of PE pipe between two rigid rings: 131mm • After 50 years: • Maximum lateral displacement of PE pipe between two rigid rings: 680mm

  17. RISER TUBE DETAILS: • Hypothesis: • Detailed FE model of riser tube between two rings (50m). • Rigid and fixed rings. • Properties at time 0. • Only lateral forces transmitted between cables and tube. • (vertical pre-tension is not transmitted to the PE-pipe). At time 0: Maximum stress of PE tube between two rigid rings: 1.67MPa (Design stress at time cero: 9.4MPa) After 50 years Maximum stress of PE tube between two rigid rings: 1.75MPa (Design stress at time cero: 6.3MPa)

  18. RISER TUBE DETAILS: Cable stresses:

  19. CONCLUSIONS: • Dome: • The dome is feasible till a bottom current velocity of about 0.3 a 0.4 m/s (without taking into account dynamic effects) • Riser tube: • A riser tube with rings minimal every 50 meter is needed to avoid large displacements of the tube within the Dyneema cables

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