1. Technodyne International Limited www.technodyne.co.uk C967 - LAGUNA LBNO LENA LSc Tank Design Update 2 Robin Atkinson LAGUNA LBNO General Meeting 1st – 3rd October 2012 Geneva, Switzerland

2. Technodyne International Limited Update 2 Presentation Summary  Tank Civil Design – Focus for Geneva  Review key design issues – stress – crack control  Discuss liner design in detail  Describe water loss provision and cost implications  Describe water test procedure  Show reinforcement details  Present Bill of Material 2 LENA LSc Tank Design Update 2

3. Technodyne International Limited Review of Design Analysis  Water TightnessAs CIRIA C660 & EC2 part 3  ForcesFEA using Staad Pro – see diagrams  Water Loss ImplicationsRisk and Cost Reinforcement Design  Reinforcement will be verified using a sophisticated spreadsheet prepared by HAC Reinforcement Detailing  Detailed drawings will use CADS which is an Autocad based program 3 LENA LSc Tank Design Update 2

4. Technodyne International Limited Water-Tightness of Concrete  Concrete will shrink due to:- Temp drop from hydration temp (Approx 30 deg) Autogenous effects – due to internal chemical changes Drying prior to service  Previous pours can offer restraint against shrinkage.  Aggregate coefficient of expansion influences shrinkage  Concrete can self heal but needs several weeks of seepage  Max net water head is 14m = 140 kN/m2  Test to a max 25m net water head = 250 kN/m2 in 10m steps  This will ensure a minimum 15m test head throughout height  Some small seepage could still occur during service  Need a reliable barrier concept 4 LENA LSc Tank Design Update 2

5. Technodyne International Limited Healing Rates of Leakage Through Concrete Cracks 5 LENA LSc Tank Design Update 2

6. Technodyne International Limited Risk v Cost  Risk must be very low but cost must be acceptable  What happens if the water jacket level drops?  Water ingress into oil chamber must be avoided  Provide a sound resistance to water ingress i.e. Crack widths in concrete < 0.2mm Inner lining designed to exclude water  How do we know if we have a leak?  Inner steel lining with an oil filled gap offers a secure barrier.  Is it viable to fix the lining directly to the concrete? 6 LENA LSc Tank Design Update 2

7. Technodyne International Limited Tank Concept Design - Option 1  Tank designed to Class 1 Crack control of EC2 (i.e. < 0.2mm width)  The tank must be water tested with water on outside to a min 15m head  Inner stainless steel lining applied and welded after the tank has been water tested allowing a 150mm oil filled gap  Inner lining with oil in gap will only have a nominal pressure differential  Any future seepage is pumped out Tank Concept Design - Option 1a  As Option 1 but with lining fixed tightly to concrete with no oil in gap. This option does not provide a hydraulic buffer against water seepage. 7 LENA LSc Tank Design Update 2

8. Technodyne International Limited Design of Stainless Steel Lining  Generally Must fix after initial concrete shrinkage Tank must be tested and leaks sealed beforehand Must resist stress due to inward movement of concrete wall  If fixed with a 150mm oil filled gap Pressure on lining would be balanced Must allow for a 5m oil head variation Can allow any water seepage to be drained off Oil pressure will reduce any water seepage pressure 8 LENA LSc Tank Design Update 2

9. Technodyne International Limited Design of Stainless Steel Lining 9 LENA LSc Tank Design Update 2

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11. Technodyne International Limited Finite Element Analysis of Concrete Tank - 1 11 Service Hoop Compressive Stress (N/mm²) External Space Filled with Water with Specific Gravity 1.0 Inside Full of Oil with Specific Gravity 0.86 100 m 0 m LENA LSc Tank Design Update 2

12. Technodyne International Limited Finite Element Analysis of Concrete Tank - 2 12 Service Vertical Moment (kNm/m) External Space Filled with Water with Specific Gravity 1.0 Inside Full of Oil with Specific Gravity 0.86 Slice from Model up to 15m Level 0 m 15 m LENA LSc Tank Design Update 2

13. Technodyne International Limited Finite Element Analysis of Concrete Tank - 4 13 Service Vertical Shear (kN/m) External Space Filled with Water with Specific Gravity 1.0 Inside Full of Oil with Specific Gravity 0.86 Slice from Model up to 15m Level 0 m 15 m LENA LSc Tank Design Update 2

14. Technodyne International Limited Finite Element Analysis of Concrete Tank - 3 14 Service Radial Displacements at Initial Loading (mm) External Space Filled with Water with Specific Gravity 1.0 Inside Full of Oil with Specific Gravity 0.86 0 mm 1.6 mm Section Through Model 0 mm 1.6 mm 0 mm 100 m 0 m 30 Year Creep Displacements will be 65% and Additional LENA LSc Tank Design Update 2 Max Strain = 1000 x 1.6 / 16 = 100 Microstrain R =16 m

15. Technodyne International Limited 15 LENA LSc Tank Design Update 2 Steel Lining Plate Analysis Cont. If the plate is fixed directly to a circular inner face, with no oil behind, it will be pushed against the concrete by the pressure of the oil. The plates will experience a compressive stress due to the contraction of the tank and this could cause a buckling deformation. A thicker plate will generate greater stress in bending due to deflection and a thinner plate will be more susceptible to buckling. So, the optimum thickness must be found that gives the best all round resistance. The option with a 150mm oil gap behind should not generate any bending as the pressure will be equal. However a nominal 5m head difference should be included in the design. If the inside concrete face was faceted, or if the gap was grouted, the plates would not be subject to bending.

16. Technodyne International Limited 16 LENA LSc Tank Design Update 2 Approx550mm

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22. Technodyne International Limited 22 LENA LSc Tank Design Update 2 Recommendation It is structurally feasible to fix the plates directly to the concrete surface but the design is more complex and sensitive to bending and the implications of buckling deformation would need to be fully investigated. However, the 150mm gap option allows the provision of a hydraulic buffer against possible leakage. This is considered to be of significant value in limiting any water ingress as a result of a 100m head. The 150mm gap option is more expensive because it requires an additional spacer section and more welding. Recommend the 150mm gap option

23. Technodyne International Limited 23 LENA LSc Tank Design Update 2 Design Scenarios Various design scenarios are considered which include  Normal Operating levels  Suggested in-service tolerated external water level drop  Suggested maximum ultimate external water level drop  Alternative ultimate external water level drop  No external water Average horizontal reinforcement is calculated for these scenarios. A comparative cost exercise is then performed to establish what is an acceptable level of design taking into account the risk and cost. 32 dia bars at 125mm vertical centres on both faces is considered to be a practical maximum local density of reinforcement. The general / average spacing would be 150mm centres.

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25. Technodyne International Limited 25 LENA LSc Tank Design Update 2 Limit crack widths to 0.2mm with 32 dia bars at 125 ctrs locally but at 150 ctrs on average

26. Technodyne International Limited 26 LENA LSc Tank Design Update 2 32 dia bars at 125 ctrs locally can remain elastic – crack widths will be large at 0.6 to 0.7mm

27. Technodyne International Limited 27 LENA LSc Tank Design Update 2 Not economic to provide for – tank will fail

28. Technodyne International Limited 28 LENA LSc Tank Design Update 2 Not economic to provide for – tank will fail

29. Technodyne International Limited 29 LENA LSc Tank Design Update 2 Crack Spacing, Reinforcement & Crack Widths due to Hoop Tension

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35. Technodyne International Limited 35 LENA LSc Tank Design Update 2 Water Testing The water testing is vital to prove the adequacy of construction and to seal any small shrinkage cracks that develop during construction. The test will be based on net external water pressure only as the net internal pressure case is an accidental condition and a test would create new cracks unnecessarily. The test must replicate a minimum of a 15m water head with no liquid on the far face. This is done by creating a 25m head above an internal water level and moving each up in steps of 10m. Each test must be kept on until any leak is reduced to an acceptably small amount. This will take on average 3 weeks per step.

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40. Technodyne International Limited 40 Risk & Cost Matrix LENA LSc Tank Design Update 2

41. Technodyne International Limited  Thank you, any questions? 41 LENA LSc Tank Design Update 2

42. Technodyne International Limited