ISO 19905-1 BENCHMARK STUDY - ASSESSMENT IN … · 3100 AR Schiedam, the Netherlands Telephone +31...

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ISO 19905-1 BENCHMARK STUDY - ASSESSMENT IN ACCORDANCE WITH SNAME REV 3 (WITH DEEP CLAY ADDITION)

MSC ref P 11512-8175 rev A

Client ISO 19905-1 Benchmarking Panel Client doc nr

PI CA FI Unit CJ62 STATUS ISSUE DATE PREPARED BY REVIEWED BY APPROVED BY

X First 0 November 19, 2010 HOF EWI HOF X Revision A November 23, 2010 HOF EWI HOF Revision B Revision C Revision D Revision E Revision F

Copyright of MARINE STRUCTURE CONSULTANTS (MSC) BV whose property this document remains. No parts thereof may be disclosed, copied, duplicated or in any other way made use of except with the written approval of MSC BV WIF-MSC-431.1.17

Marine Structure Consultants (MSC) bv

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Marine Structure Consultants (MSC) bv WIF-MSC-431.1.17

TABLE OF CONTENTS

1. INTRODUCTION .......................................................................................... 1

2. ASSESSMENT OF THE NORTH SEA-SAND SITE .................................... 2

2.1. SITE CONDITIONS ............................................................................................................ 2

2.2. SOIL CONDITIONS ............................................................................................................ 3

2.3. RIG DATA ........................................................................................................................... 3

2.4. LEG PENETRATION ESTIMATE ....................................................................................... 4

2.5. FOUNDATION STIFFNESS FOR THE FIXITY CASE ....................................................... 4

2.6. LEG LENGTH RESERVE AND HULL ELEVATION CHECKS .......................................... 5

2.7. EXTERNAL LOADS ............................................................................................................ 5

2.8. PINNED CASE ................................................................................................................... 6

2.9. FIXITY CASE ...................................................................................................................... 9

2.10. CONCLUSION ................................................................................................................ 11

3. ASSESSMENT OF THE GULF OF MEXICO-CLAY SITE ......................... 12

3.1. SITE CONDITIONS .......................................................................................................... 12

3.2. SOIL CONDITIONS .......................................................................................................... 13

3.3. RIG DATA ......................................................................................................................... 13

3.4. LEG PENETRATION ESTIMATE ..................................................................................... 14

3.5. FOUNDATION STIFFNESS FOR (DEEP PENETRATION) FIXITY CASE ..................... 14

3.6. LEG LENGTH RESERVE AND HULL ELEVATION CHECKS ........................................ 15

3.7. EXTERNAL LOADS .......................................................................................................... 15

3.8. RESULTS FOR DEEP PENETRATION CASE ................................................................ 16

3.9. CONCLUSION .................................................................................................................. 19

4. SUMMARY OF RESULTS ......................................................................... 20

5. REFERENCES ........................................................................................... 21

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FIGURES & TABLES APPENDIX A Basic analysis methodology APPENDIX B LEGLOAD results for North Sea sand – pinned case APPENDIX C LEGLOAD RESULTS for North Sea sand – fixity case APPENDIX D Attachment from [ref 4] for use in SNAME clay assessment APPENDIX E` LEGLOAD results for Gulf of Mexico – clay case

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1. INTRODUCTION

The present report is part of the ISO 19905-1 phase 2 Benchmark study based on the ISO 19905-1 DIS 2009 [ref 1] documenting a complete assessment in accordance with SNAME rev 3 [ref 1] in line with the Request for Bid [ref 2]. For the fixity calculations of the clay site, additional Deep Penetration Guidance is used [ref 4].

The analyses have been done for the MSC CJ62 jack-up for a typical North Sea sand site and a typical Gulf of Mexico clay site. Site specific soil data as applied have been received from the Benchmark Panel. Met-ocean conditions are selected by MSC to arrive at utilizations around 1.

The main analysis is performed using the in-house MSC jack-up analysis program LEGLOAD assisted with spreadsheets such as to perform checks and penetration analyses.

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2. ASSESSMENT OF THE NORTH SEA-SAND SITE

This section documents the general input and results for the all sand site as provided which is taken to be a typical North Sea location with representative North Sea met-ocean conditions.

2.1. SITE CONDITIONS

The site assessment is performed for the unit in survival mode with selected 50-yr return period environmental conditions and received soil data for the site.

2.1.1. ENVIRONMENTAL CONDITIONS

The 50-yr return period omni-directional wind, waves, current and SWL are selected as listed below: • Max wave height 28.0 m • Associated wave period 15.8 s • Wind velocity (1 min) 45.0 m/s • Current velocity:

• At surface 1.00 m/s • 75% of depth 0.95 m/s • -50% of depth 0.90 m/s • 25% of depth 0.80 m/s • 1% of depth 0.50 m/s

• SWL above LAT 2.0 m

The wind velocity is defined at a height of 10 m above water level. For other heights the wind speed is given by: U(z) = U(10) x (z/10)0.09. The current speed is linearly interpolated between depth intervals.

No distinction is made between Intrinsic or Apparent wave period.

2.1.2. WATERDEPTH AND AIRGAP

The waterdepth at the site is taken as 104.7 m LAT. Maximum (total) water depth including SWL is then 106.7 m. An airgap of 25 m (to LAT) was taken.

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2.1.3. MARINE GROWTH

A marine growth thickness of 12.5 mm is taken into account on the entire leg length below MSL +2 m.

2.2. SOIL CONDITIONS

The soil conditions are taken from [ref 3] and summarized below: • Internal friction angle 34 deg • Effective submerged weight 11 kN/m3 • Steel-soil friction angle 29 deg • Relative density Dr 65% • Poisson’s ratio 0.2 • Shear modulus G 23765 x √(Vswl/(101.3A)

2.3. RIG DATA

See figures 2.1 and 2.2.

2.3.1. WEIGHT AND COG (loading conditions)

The elevated weight and eccentricities in survival conditions are taken from the Operations Manual.

The maximum elevated weight is 17118 t composed of light elevated weight and variable load. The minimum elevated weight is taken as lightweight plus 50% of the maximum variable load. For both maximum and minimum elevated weight the eccentricities relative to the center of legs are: • Longitudinal -2.20 m to +0.45 m (- is aft, + is forward) • Transverse 0.35 m to either side

2.3.2. LEGS

• Number of legs 3 • Longitudinal leg distance 53.7 m • Transverse leg distance 62.0 m • Type of leg triangular lattice • Bracing type X • Leg length 175.3 m • Leg face width 16 m • Spudcan diameter (equivalent) 17.84 m • Spudcan area 250 m2

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The leg-to-hull connection is provided by active fixation systems on all chords.

2.3.3. Pre-load conditions

The applied pre-load is 152.9 MN at spudcan level.

2.4. LEG PENETRATION ESTIMATE

The method of section 6.2.3 is applied, using: • Steel/soil friction angle = 29 deg • γ’ = 11 kN/m3 • Nγ = 19.33 • Sγ = 0.6 • Pre-load = 152.9 MN

At full contact area the resistance is approx 285 MN. At pre-load, the equivalent contact diameter is 14.5 m approx., which agrees with 1.45 m penetration. Partial contact is achieved.

The results are closely comparable to ISO DIS 2009 leg penetration results. For consistency between the analyses, the same values are used further: • Leg penetration 1.4 m • Contact diameter 14 m

2.5. FOUNDATION STIFFNESS FOR THE FIXITY CASE

The effect of foundation fixity is included in the (fixity case) analysis, using a yield surface approach according to section 6.3.4. The shear modulus is selected using the Commentaries resulting in initial stiffness and capacities: • Vl0 152.9 MN • HL0 18.3 MN • ML0 160.5 MNm

• G 46 MN/m2 • K1 2340 MN/m • K2 222 MN/m • K3 918 MNm/deg

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For the dynamic analysis (natural period calculation) the rotational stiffness is taken as 80% of K3.

The yield surface approach that is implemented in the program LEGLOAD implicitly checks the foundation by reducing the rotational soil stiffness until the combined vertical, horizontal and moment load falls within the defined yield surface.

2.6. LEG LENGTH RESERVE AND HULL ELEVATION CHECKS

For airgap calculations the clearance of the 50-yr wave with additional margin must be checked. The minimum airgap requirement, relative to LAT, is calculated below: • Tidal amplitude and surge 2.0 m • Wave elevation 16.1 m • Margin 1.5 m • Minimum airgap to LAT 19.6 m

The specified airgap of 25 m exceeds the minimum requirements for this location.

The reserve leg length is determined as follows: • Available total leg length 175.3 m • Leg penetration 1.4 m • Waterdepth (LAT) 104.7 m • Airgap to LAT 25.0 m • Top of jack-house above base of hull 25.0 m

Reserve leg length is 19.2 m.

The minimum required leg length reserve is 1.5 m.

2.7. EXTERNAL LOADS

External loads are determined using: • Deterministic approach • SDOF approach for DAF

2.7.1. WIND AREA

The effective wind area of the hull is 2650 m2, at a level of 18.0 m above base of hull based on wind tunnel tests. This wind area is used for all

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directions. A representative Cd is used for the leg CD related to wind loads.

2.7.2. HYDRODYNAMIC LEG PROPERTIES

The CD and CM of the legs are determined in accordance with section 4.6 [ref 1] using the ‘equivalent leg model’. The leg is divided in a smooth part above MSL + 2 m, and a rough part below. For the rough part a marine growth thickness of 12.5 mm is added.

The reference values for tubular are: CD CM

smooth 0.65 2.0

rough 1.0 1.8

The total leg coefficients are related to the leg reference diameter (= 16 m). The effect of raw water risers, jet pipes, etc. is taken into account.

2.7.3. Wave theory, kinematics reduction factor and current blockage factor

Stokes-5 wave theory is considered to be appropriate, see figure 2.2.

In order to obtain realistic wave forces in combination with a Stokes 5th order regular wave analysis, a kinematic reduction factor of 0.86 is applied to the wave height in line with instruction from the Benchmark Panel.

A current blockage factor of 0.92 is used.

2.8. PINNED CASE

The maximum wave/current overturning moment is selected for the assessment.

2.8.1. Inertia loading (pinned case)

The damping used is total 5% of critical, thought to be comprised of: • Structural 2% • Hydrodynamic 2% • Foundation 1% • Total 5%

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Natural Periods and DAF's: • Hull weight 17118 t (max) • TN 9.0 s (for all directions sway/surge) • Tw 15.8 s • Damping 5% • DAFSDOF 1.47

2.8.2. ACTION SUMMARY pinned case

The factored actions used in/resulting from the Extreme Storm analysis are listed below:

heading [deg] [deg] 180 210 240

base shear (factored)

wind [MN] 5.158 5.185 5.160

wave/current [MN] 16.785 17.159 17.018

inertial [MN] 4.569 4.683 4.654

total base shear [MN] 26.512 27.027 26.832

OTM

wind [MNm] 762.7 766.8 763.0

wave/current [MNm] 1354.3 1381.5 1374.1

inertial [MNm] 647.0 663.1 659.1

total OTM [MNm] 2764 2811 2796

Load factor on environmental loads (γ = 1.15) included.

Reference elevation for OTM = wrt support point at 0.4 m below mud line.

See figure 2.3 for wave heading definition.

2.8.3. Global response analysis

For the global response calculations the MSC jack-up assessment program LEGLOAD is used. The program applies a quasi-static design wave approach together with a non-linear (large displacements) FE-model. The dynamic behaviour is taken into account by a Single Degree Of Freedom (SDOF) analogy.

LEGLOAD output for relevant cases is included in appendix B.

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2.8.4. Overturning stability

The overturning stability unity check is 0.97. For maximum (100% variable load) weight, the utilization reduces to 0.94.

2.8.5. Leg strength

The highest chord strength unity check found is UC = 1.09.

2.8.6. Fixation system capacity

The fixation system has a characteristic resistance of 145 MN, giving a design resistance of 123 MN. The fixation system unity check is 0.90.

2.8.7. Foundation check

Step 1 pre-load check is used as a first level bearing check for the NS sand – pinned case under the following restrictions: • Analyses model is based on a pinned footing support response model • The ratio of Fh over Fv must fall within the range applicable to partial

contact conditions, Qh < 0.1 VL0

The first is true, the second depends on the soil reaction. The soil reaction for the leeward leg is Fh of 8.94 which is well within 0.1 VL0. Therefore the step 1 pre-load is found applicable. However, for comparison a step 2a VH bearing check was performed (for pinned condition) as well.

The resulting pre-load unity check is: • UC = 140 / (0.90 x 152.9) = 1.02

Taking into consideration that only 1 cm additional penetration will lead to a satisfactory unity check, the check is assessed acceptable as per SNAME guidelines. A step 3 analysis is therefore not required.

Step 2a is based on the formula for vertical-horizontal capacity envelope as per section 6.3.3.1, whereby the pre-loading capacity of the unit at the soil of VL,0 = 152.9 MN is found with the associated effective friction angle of 29 deg. Side resistance is considered (Rh = 0.12 MN). The required resistance factor for partial contact is φVH = 0.90.

The vector of the loads with respect to the origin of the loads in still water level, being Vswl = 79 MN for leeward legs, are constructed. The capacity vector is found with respect to the still water load in the same direction as

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the load vector. This capacity vector is factored by φVH. The utilization is found as: UC = vector of loads wrt Vswl / factored capacity vector wrt Vswl

Un-factored yield surface, load and capacity vectors and results are shown in figure 2.4.

Sliding of the windward leg is found to exceed 1.0 based on the step 1b check. Step 2b approach is applied as per below.

2.9. FIXITY CASE


2.9.1. Inertia loading (fixity case)

• Hull weight 17118 t (max) • TN 7.1 s (for all directions sway/surge) • Tw 15.8 s • Damping 5% • DAFSDOF 1.25

2.9.2. ACTION SUMMARY fixity case

The factored actions used in/resulting from the Extreme Storm analysis are listed below:


base shear (factored) wind

wind [MN] 5.158 5.185 5.160

wave/current [MN] 16.785 17.159 17.018

inertial [MN] 2.420 2.480 2.465


OTM

wind [MNm] 762.7 766.8 763.0

wave/current [MNm] 1354.3 1381.5 1374.1

inertial [MNm] 342.7 351.2 349.1

total OTM [MNm] 2459.7 2499.5 2486.2


Reference elevation for OTM = wrt support point at 0.4 m below mud line.

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LEGLOAD output for relevant cases is included in appendix C.


The resulting overturning stability unity check is 0.79.

2.9.5. Leg strength

The leg strength unity check at lower guide level is 0.92.


The fixation system unity check is 0.76.


The same conditions have been used as for the NS sand – pinned case, except that fixity was applied in the response model. The soil reactions thus differ from the pinned case.

In addition, the step 1 pre-load check is not applicable as the response model was not based on pinned supported condition. For fixity calculations step 2b applies. The leg reaction vector complies with the VHM yield surface. For foundation capacity checking refers further to step 2a. Results are shown in figure 2.5.

Step 2a was applied in the same way as for the previous case. Utilisations found are: • Foundation capacity UC = 1.05 • Sliding UC = 0.98

Step 2a was thus applied in the same way as for the previous case. Since the maximum utilization exceeds 1.0 a step 3 further assessment is adopted here (but not reported further) to verify that with additional

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penetration of only a few centimetres the situation is found acceptable. Sliding is found to be acceptable (UC = 0.98).

2.10. CONCLUSION

The results for assessment for the typical North Sea sand site conditions in accordance with the SNAME Recommended Practice rev 3 [ref 1], as described in the previous sections, results in the utilizations as summarized below:

criteria sand - pinned case sand - fixity case

overturning stability 0.97 0.79

chord strength at lower guide level 1.09 0.92

fixation system capacity 0.90 0.76

pre-load check 1.02 - **)

foundation capacity leeward 1.27 1.05

sliding 50% var load 3.7 0.98

sliding 100% var load 2.9 0.88

**) = Not applicable for a fixity case.

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3. ASSESSMENT OF THE GULF OF MEXICO-CLAY SITE

This section documents the general input and results for the deep penetration clay site as provided which is taken to be a typical Gulf of Mexico location with representative met-ocean conditions.

3.1. SITE CONDITIONS

The site assessment is performed for the unit in survival mode with selected 50-yr return period environmental conditions and received soil data for the site.

3.1.1. ENVIRONMENTAL CONDITIONS

The 50-yr return period omni-directional wind, waves, current and SWL are selected as listed below: • Max wave height 22.0 m • Associated wave period 16.0 s • Wind velocity (1 min) 50.0 m/s • Current velocity

• At surface 1.50 m/s • 75% of depth 1.43 m/s • 50% of depth 1.35 m/s • 25% of depth 1.20 m/s • 1% of depth 0.75 m/s

• SWL above LAT 2.5 m

The wind velocity is defined at a height of 10 m above water level. For other heights the wind speed is given by: U(z) = U(10) x (z/10)0.09. The current speed is linearly interpolated between depth intervals.

3.1.2. WATERDEPTH AND AIRGAP

The waterdepth at the site is taken as 80.0 m LAT. Maximum (total) water depth including SWL is then 82.5 m. An airgap of 20 m (to LAT) was taken.

3.1.3. MARINE GROWTH

A marine growth thickness of 12.5 mm is taken into account on the entire leg length below MSL +2 m.

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3.2. SOIL CONDITIONS

The soil conditions are taken from [ref 3] and summarized below or specified in figure 3.1: • Soil type very soft to stiff calcareous clay • Effective submerged weight 4 - 9 kN/m3 (see figure 3.1) • Un-drained shear strength 4 + 1.31 z (see figure 3.1) • OCR 1.0 – 1.4 (see figure 3.1) • Poisson’s ratio 0.5 • Sensitivity ratio 2.7 • Shear modulus see figure 3.1

3.3. RIG DATA

3.3.1. WEIGHT AND COG (loading conditions)

The elevated weight and eccentricities in survival conditions are taken from the Operations Manual.

The maximum elevated weight is 17118 t composed of light elevated weight and variable load. The minimum elevated weight is taken as lightweight plus 50% of the maximum variable load. For both maximum and minimum elevated weight the eccentricities relative to the center of legs are: • Longitudinal -2.20 m to +0.45 m (- is aft, + is forward) • Transverse 0.35 m to either side

3.3.2. LEGS

• Number of legs 3 • Longitudinal leg distance 53.7 m • Transverse leg distance 62.0 m • Type of leg triangular lattice • Bracing type X • Leg length 175.3 m • Leg face width 16 m • Spudcan diameter (equivalent) 17.84 m • Spudcan area 250 m2

The leg-to-hull connection is provided by active fixation systems on all chords.

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3.3.3. Pre-load conditions

The applied pre-load is 152.9 MN at spudcan level.

3.4. LEG PENETRATION ESTIMATE

The method of section 6.2.2 and commentaries is applied which results in approx 40-44 m penetration of the maximum contact area, see figure 3.1. This is in close agreement with the ISO result. Backflow and infill is expected to occur resulting in an estimated F’0A – γ’V = 36.7 MN.

Cavity remaining after pre-loading may be up to 8 m equivalent to 8 MN soil weight. The effect of in-fill is added to the (net) soil reactions resulting from the storm.

3.5. FOUNDATION STIFFNESS FOR (DEEP PENETRATION) FIXITY CASE

The effect of foundation fixity is included in the (fixity case) analysis, using a yield surface approach according to section 6.3.4. Upon request from the Benchmarking Panel [ref 4], the SNAME rev 3 (shallow) clay fixity capacities have been replaced by the capacities as indicated in the text received, see appendix D, whereby: • VLo = pre-load capacity 152.9 MN • HLo = cuoA + (cuo + cu1) As 19.2 MN • MLo = (0.1 + 0.05a(1+b/2)) VLo B 428 MNm

The capacities are based on net capacities for the deep penetration case with a = 0.99, b = 0.303, As = 26.76 m2, A = 250 m2, cu0 = 63.7 kPa, cu1 = 60 kPa and B = 17.84 m.

The shear modulus is selected using the Commentaries. The shear modulus is limited to G/su < 600 as per recommendation in the Commentaries. Embedment factors are included (approx 2.2) for a Poisson’s ratio of 0.5. This results in the following initial stiffnesses: • G 34 MN/m2 • K1 4370 MN/m • K2 2910 MN/m • K3 4850 MNm/deg

For the dynamic analysis (natural period calculation) the rotational stiffness is taken as 80% of K3.

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The yield surface approach that is implemented in the program LEGLOAD implicitly checks the foundation by reducing the rotational soil stiffness until the combined vertical, horizontal and moment load falls within the defined yield surface. The stiffness reduction factor is as per section 6.3.4.3, so different from the ISO definition. However, all failure ratios are (close to) 1.0 which means that the yield capacities determine the final remaining fixity.

3.6. LEG LENGTH RESERVE AND HULL ELEVATION CHECKS

For airgap calculations the clearance of the 50-yr wave with additional margin must be checked. The minimum airgap requirement, relative to LAT, is calculated below: • Tidal amplitude and surge 2.5 m • Wave elevation 12.7 m • Margin 1.5 m • Minimum airgap to LAT 16.7 m

The specified airgap of 20 m exceeds the minimum requirements for this location.

The reserve leg length is determined as follows: • Available total leg length 175.3 m • Leg penetration 45.6 m • Waterdepth (LAT) 80.0 m • Airgap to LAT 20.0 m • Top of jack-house above base of hull 25.0 m

Reserve leg length is 4.7 m.

The minimum required leg length reserve is 1.5 m.

3.7. EXTERNAL LOADS

External loads are determined using: • Deterministic approach • SDOF approach for DAF

3.7.1. WIND AREA

The effective wind area of the hull is 2650 m2, at a level of 18.0 m above base of hull based on wind tunnel tests. This wind area is used for all

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directions. A representative Cd is used for the leg CD related to wind loads.

3.7.2. HYDRODYNAMIC LEG PROPERTIES

The CD and CM of the legs are determined in accordance with section 4.6 [ref 1] using the ‘equivalent leg model’. The leg is divided in a smooth part above MSL + 2 m, and a rough part below. For the rough part a marine growth thickness of 12.5 mm is added.

The reference values for tubular are: CD CM

smooth 0.65 2.0

rough 1.0 1.8

The total leg coefficients are related to the leg reference diameter (= 16 m). The effect of raw water risers, jet pipes, etc. is taken into account.

3.7.3. Wave theory, kinematics reduction factor and current blockage factor

Stokes-5 wave theory is considered to be appropriate.

In order to obtain realistic wave forces in combination with a Stokes 5th order regular wave analysis, a kinematic reduction factor of 0.86 is applied to the wave height in line with instruction from the Benchmark Panel.

A current blockage factor of 0.92 is used.

3.8. RESULTS FOR DEEP PENETRATION CASE


3.8.1. Inertia loading

• Hull weight 17118 t (max) • TN 6.0 s (for all directions sway/surge) • Tw 16.0 s (apparent, see above) • Damping 5% (additional damping of deep penetration in clay

neglected) • DAFSDOF 1.16

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3.8.2. ACTION SUMMARY

The factored actions used in/resulting from the Extreme Storm analysis are listed below.


base shear (factored)

wind [MN] 5.762 5.773 5.764

wave/current [MN] 14.933 15.232 15.120

inertial [MN] 1.305 1.331 1.325


OTM

wind [MNm] 927 929 927

wave/current [MNm] 1537 1569 1558

inertial [MNm] 203 207 206

total OTM [MNm] 2667 2705 2691


Reference elevation for OTM = wrt support point at 44 m below mud line.




LEGLOAD output for relevant cases is included in appendix E.


The resulting overturning stability unity check is 0.61.

3.8.5. Leg strength

The leg strength unity check at lower guide level is 0.70.


The fixation system unity check is 0.59.

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The step 1 pre-load check is not applicable as the response model was not based on pinned supported condition. For fixity calculations step 2b applies which for foundation capacity checking refers further to step 2a. Step 2a was thus applied in a similar same way as for the sand cases.

Step 2a is based on the formula for vertical-horizontal capacity envelope of section 6.3.3.2 and section 6.2.2 for penetration in clay. The ultimate vertical bearing capacity of clay is equal to pre-load taking into account the effect of backflow and soil replaced by the spudcan: • VL0 = Fv – F0’ A + γ’V Where: Fv = (cu0Ncscdc + p0’) A for zero horizontal loading F0’ A - γ’V = 36.7 MN

This results in Fv = 189 MN, taken as the ultimate capacity of at the soil comprising VL,0 = 152.9 MN and F0’ A + γ’V = 36.7 MN. Full contact is achieved. In line with section 6.3.3.2 the associated horizontal capacity at a certain Fv includes side resistance: • FH = FH + (su0 + su1) x As

The required resistance factor for full contact is φVH = 0.85.

The vector of the loads with respect to the origin of the loads in still water level, being Vswl = 82 MN which includes the additional weight of 8 MN infill after pre-loading, are constructed. The capacity vector is found with respect to the still water load in the same direction as the load vector. This capacity vector is factored by φVH. The utilization is found as

UC = vector of loads wrt. Vswl/ factored capacity vector wrt Vswl.

Un-factored yield surface, load and capacity vectors and results are presented in figure 3.2. Utilisations found are: • Foundation capacity UC = 0.83 • Sliding UC = 0.67

For the purpose of the present Benchmark study, the verification does not progress beyond this level of checks which could be a step 3 procedure.

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3.9. CONCLUSION

The results for assessment for the typical Gulf of Mexico (soft) clay site conditions in accordance with the SNAME recommended Practice revision 3 [ref 1] with the prescribed Deep Clay Fixity addition [ref 4], as described in the previous sections, results in the utilizations as summarized below:

criteria clay case

overturning stability 0.61

chord strength at lower guide level 0.70

fixation system capacity 0.59

pre-load check -*)

foundation capacity leeward 0.83

sliding 50% var load 0.67

*) = Not applicable for a fixity case

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4. SUMMARY OF RESULTS

A summary of the assessment results for sand-pinned, sand-fixity cases and clay case is provided in the table below:

criteria sand - pinned case

sand - fixity case

clay case

overturning stability 0.97 0.79 0.61

chord strength at lower guide level 1.09 0.92 0.70

fixation system capacity 0.90 0.76 0.59

pre-load check 1.02 - **) -*)

foundation capacity leeward 1.27 1.05 0.83

sliding 50% var load 3.7 0.98 0.67

*) = Not applicable for a fixity case

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5. REFERENCES

[1] SNAME Recommended Practice for Site-specific Assessment of Mobile Offshore Units Rev 3, 2008

[2] ISO Benchmark committee ISO Phase 2 Benchmarking of ISO 19905-1 Request for Bid Received by email from J. Stiff, 24 Jun 2009

[3] ISO Benchmark committee ‘Official request to commence ‘Early start’ work on phase 2 Benchmarking’ Received by email from J. Stiff, 05 Nov 2009

[4] ISO Benchmark Committee ISO Benchmarking – Deep penetration addition to SNAME analyses Received by email from J. Stiff, 12 May 2010

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Figure 2.1.: MSC CJ62 type drilling rig, here in skid-over mode on Froy.

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Figure 2.2.: View on the spudcan.

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Figure 2.3.: Heading of external loading.

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BEARING SLIDINGPreload at leg tip 152.9 MN Friction angle sliding 34 degReq'd resistance factor 0.90 - Side resistance 0.00 MN

Req'd resistance factor 0.80 -Heading 240 210 180 Heading 240 210 180Leg 1 2 4 Leg 2 2 1horizontal [MN] - Legload 8.5 8.3 8 Hor [MN] 9.285 10.800 10.500vertical [MN] - Legload 140 132 109 Vert [MN] 36.643 6.900 5.200

UTILIZATIONS (bearing) UTILIZATIONS (sliding)Heading 240 210 180 Heading 240 180 full 180Bearing SlidingLeg 1 2 4 Leg 2 2 1horizontal [MN] 8.5 8.3 8vertical [MN] 140.000 132.000 109.000 FH 15.949 4.654 3.507H_Still Water [MN] 0.000 0.000 0.000 QH 9.285 10.800 10.500V_Still Water [MN] 79.000 79.000 79.000 QV 36.643 6.900 5.200Safety (All./Actual) [-] 0.87 0.97 1.38 safety 1.72 0.43 0.33Min required safety 1.11 1.11 1.11 required safe 1.25 1.25 1.25UC 1.27 1.15 0.81 UC 0.73 2.90 3.74

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Foundation sliding and bearing capacityYield surfaceBearing margin Leg 1 Heading 240Bearing margin Leg 2 Heading 210Bearing margin Leg 4 Heading 180Sliding capacitySliding margin Leg 2 Heading 240Sliding margin Leg 2 Heading180 fullSliding margin Leg 1 Heading 180

Figure 2.4.: Foundation checks for pinned case.

Revision A



BEARING SLIDINGPreload at leg tip 152.9 MN Friction angle sliding 34 degReq'd resistance factor 0.90 - Side resistance 0.12 MN

Req'd resistance factor 0.80 -Heading 240 210 180 Heading 240 180 full 180Leg 1 2 4 Leg 2 2 1horizontal [MN] - Legload 7.6 7.7 7.82 Hor [MN] 8.600 8.780 8.590vertical [MN] - Legload 127.5 121.8 120.6 Vert [MN] 43.000 18.300 16.020

UTILIZATIONS (bearing) UTILIZATIONS (sliding)Heading 240 210 180 Heading 240 180 full 180Bearing SlidingLeg 1 2 4 Leg 2 2 1horizontal [MN] 7.6 7.7 7.82vertical [MN] 127.500 121.800 120.600 FH 17.226 12.459 10.922H_Still Water [MN] 0.000 0.000 0.000 QH 8.600 8.780 8.590V_Still Water [MN] 79.000 79.000 79.000 QV 43.000 18.300 16.020Safety (All./Actual) [-] 1.06 1.14 1.16 safety 2.00 1.42 1.27Min required safety 1.11 1.11 1.11 required safe 1.25 1.25 1.25UC 1.05 0.97 0.96 UC 0.62 0.88 0.98

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Foundation sliding and bearing capacityYield surfaceBearing margin Leg 1 Heading 240Bearing margin Leg 2 Heading 210Bearing margin Leg 4 Heading 180Sliding capacitySliding margin Leg 2 Heading 240Sliding margin Leg 2 Heading180 fullSliding margin Leg 1 Heading 180

Figure 2.5.: Foundation checks for fixity case.

Revision A



D B dc z g' p0' r1 su‐profile su(z=D+B/2su, avg q, bear Rbear[m] [m] [‐] [m] [kN/m^3] [kPa/m] [kPa] [kPa] [kPa] [kPa] [MN]

0 17.84 1.00 0 4 0 1.31 2.4 14.0852 8.2426 50.84036 12.708325 17.84 1.06 5 4 20.0 1.31 8.95 20.6352 14.7926 116.3551 29.08474

10 17.84 1.11 10 4 40.0 1.31 15.5 27.1852 21.3426 186.3991 46.593315 17.84 1.17 15 4 60.0 1.31 22.05 33.7352 27.8926 260.9723 65.23419 17.84 1.21 19 5.8 76.0 1.31 27.29 38.9752 33.1326 323.8919 80.961725 17.84 1.28 25 5.8 110.8 1.31 35.15 46.8352 40.9926 434.5062 108.611430 17.84 1.34 30 5.8 139.8 1.31 41.7 53.3852 47.5426 531.667 132.898335 17.84 1.39 35 5.8 168.8 1.31 48.25 59.9352 54.0926 633.357 158.317240 17.84 1.45 40 5.8 197.8 1.31 54.8 66.4852 60.6426 739.5761 184.868345 17.84 1.50 45 8 226.8 1.96 67.0 84.4832 75.7416 927.5613 231.858150 17.84 1.50 50 8 266.8 1.96 76.8 94.2832 85.5416 1058.231 264.520955 17.84 1.50 55 8 306.8 1.96 86.6 104.0832 95.3416 1188.9 297.183860 17.84 1.50 60 8 346.8 1.96 96.4 113.8832 105.1416 1319.57 329.846665 17.84 1.50 65 8 386.8 1.96 106.2 123.6832 114.9416 1450.24 362.509570 17.84 1.50 70 8 426.8 1.96 116 133.4832 124.7416 1580.909 395.172375 17.84 1.50 75 8 466.8 1.96 125.8 143.2832 134.5416 1711.579 427.835280 17.84 1.50 80 8 506.8 1.96 135.6 153.0832 144.3416 1842.248 460.498

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Figure 3.1.: Leg penetration in soft clay.

Revision A



assumed fully embedded and suction availablefooting reactions 240 210 180 180Q_V MN 122.1 117 40.5 37.7 INCLUDING 8 MN back-fillQ_H MN 7 7.1 8.1 8Q_M MNm 337 350 377 377f_1 1 1 1 1f_2 1 1 1 1r_f - 1.031752344 1.0500031 1.117328 1.1152914K_final MNM/defailure failure failure failure

Foundation assessmentphi_p 0.9 - resistance factor for foundation during preloadphi_Hfc 0.64 -phi_VH 0.85 - 152.86 152.86 152.86 152.86

max bearing area assumed to be mobilisedV_stat MN 82 82 74 74

UC preload - 0.89 0.85 0.29 0.27

F_H ! MN 18.816 18.816 18.816 18.816UC horizontal - 0.58 0.59 0.67 0.66

H surface MN 10.12 11.12 17.89 16.31V surface MN 138.87 136.39 0.00 0.00(H/V-Vstat) - 0.18 0.20 -0.24 -0.22UC VH - 0.83 0.76 0.53 0.58

graph

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Q vector static DNV surface factored surface

Figure 3.2.: SNAME rev 3 – GoM clay.

Revision A

P 11512-8175


APPENDIX A

BASIC ANALYSIS METHODOLOGY

Revision A

P 11512-8175 A-1.


A general description of the basic method is given.

The overall analysis is performed using the in-house developed MSC program LEGLOAD, based on a quasi-static and geometrically non-linear method. The P ∆ effect has been taken into account in the calculations. The effect of dynamics will be assessed in terms of structural properties (first natural period) and environmental properties (wave period and amplitude of cyclic loading).

For a given design wave the program calculates the instant that results in the maximum overturning moment. For this wave position, detailed wave, current and wind forces are calculated. With these forces the program determines the overall response (deflections and loads) taking into account geometric non-linear behaviour of the structure. To provide some background, the following items are briefly discussed.

Geometric input

The following items are required for the geometric input: • Distance between the legs • The elevation of the platform • The penetration of the leg into the seabed • The location of the seabed support point • The height of the jacking structure • The elevation of the lower guide

Weight input

The following items are required for the weight input: • The elevated weight and the horizontal position of the center of gravity • The weight and buoyancy of the legs; the submerged weight of the leg

footing is also specified

Structural input

The effective leg stiffness is calculated taking into account the actual leg scantlings of the chords (for bending stiffness) and bracings (to take into account shear deformation). The stiffness of the leg-to-hull interface is represented by a rotational linear spring and depends on the actual configuration of the leg-to-hull interface.

Revision A

P 11512-8175 A-2.


The hull stiffness is modelled with beam elements between the three legs. These beams have representative stiffnesses.

Foundation

Either pinned support footing or fixity in accordance with the method described in the SNAME-RP or ISO is taken into account. The stiffness and capacities are based on geotechnical calculations and guidance in the relevant document.

Hydrodynamic input

The drag and inertia coefficients CD and CM are used as generalized applicable to the legs as single sticks. The coefficients are calculated on the basis of all elements of the leg, each with their own diameter and CD/ CM coefficients. This also includes a provision for non-structural elements such as jetting lines and raw water pipes.

Environmental input

The environmental input is taken directly from the specified design conditions specified as 50 year return period conditions. Wave/current loading and wind loading on the legs are calculated by the program. The wind area of the hull is calculated separately.

Wave theory

The use of a deterministic, regular wave analysis method requires an appropriate wave theory, based on waterdepth, wave height and period.

Current

The surface, mid-depth and bottom current are specified. Current velocities at all depths are based on linear interpolation.

Wind

The wind load is calculated for three main parts: • The hull • The legs below the hull base • The legs above the top of the jacking structures

Revision A

P 11512-8175 A-3.


The wind load on the hull is based on an effective wind area and wind arm above the base. LEGLOAD will lift the hull to its airgap accounting for the specified wind profile.

Dynamics

The natural period of the unit is determined with the program. Based on a SDOF analogy, the DAF is calculated and equivalent inertia loading is determined.

Revision A

P 11512-8175


APPENDIX B

LEGLOAD RESULTS FOR NORTH SEA SAND –

PINNED CASE

Revision A

P 11512-8175 B-1.


---------------------------------------------- * * ****** ****** - 1 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:10:19 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - pinned case Case: Survival heading 180 *** Operational data *** *** Environmental conditions *** Elevated weight..: 167.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 180.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.475 m Overturning stability: 1.115 over legs 2 and 3 Natural period.......: 9.014 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 16.785 1354.32 80.687 180. Wind........: 5.158 762.71 147.882 180. Dynamic.....: 4.569 647.04 141.600 180. Load / leg .............: 1 2 3 Waveload inline.(MN ): 4.148 6.318 6.318 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 79.520 81.070 81.070 Guides........hor.(MN ): 6.633 1.815 1.838 .......vert.(MN ): -11.448 90.653 88.725 .....moment.(MN.m): 1264.968 988.295 985.943 Footing.......hor.(MN ): 10.781 7.915 7.935 .......vert.(MN ): 6.872 108.912 106.985 .....moment.(MN.m): 0.000 0.000 0.000 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.295 0.295 0.295 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 B-2.


---------------------------------------------- * * ****** ****** - 2 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:10:19 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - pinned case Case: Survival heading 210 *** Operational data *** *** Environmental conditions *** Elevated weight..: 167.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 210.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.473 m Overturning stability: 1.296 over legs 2 and 3 Natural period.......: 9.014 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 17.159 1381.52 80.515 210. Wind........: 5.185 766.82 147.891 210. Dynamic.....: 4.683 663.05 141.600 210. Load / leg .............: 1 2 3 Waveload inline.(MN ): 5.647 4.711 6.801 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 81.229 77.500 82.010 Guides........hor.(MN ): 5.075 3.734 1.583 .......vert.(MN ): -4.110 113.554 58.486 .....moment.(MN.m): 1178.247 1170.909 957.915 Footing.......hor.(MN ): 10.601 8.278 8.383 .......vert.(MN ): 14.165 131.901 76.735 .....moment.(MN.m): 0.000 0.000 0.000 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.305 0.305 0.305 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 B-3.


---------------------------------------------- * * ****** ****** - 3 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:10:19 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - pinned case Case: Survival heading 240 *** Operational data *** *** Environmental conditions *** Elevated weight..: 167.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 240.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.499 m Overturning stability: 2.400 over legs 2 and 3 Natural period.......: 9.014 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 17.018 1374.08 80.743 240. Wind........: 5.160 763.00 147.870 240. Dynamic.....: 4.654 659.07 141.600 240. Load / leg .............: 1 2 3 Waveload inline.(MN ): 6.430 4.158 6.430 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 82.193 76.258 82.193 Guides........hor.(MN ): 2.981 4.310 2.875 .......vert.(MN ): 18.402 121.610 27.919 .....moment.(MN.m): 1005.169 1256.312 1015.360 Footing.......hor.(MN ): 9.285 8.468 9.189 .......vert.(MN ): 36.643 139.967 46.158 .....moment.(MN.m): 0.000 0.000 0.000 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.295 0.295 0.295 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 B-4.


---------------------------------------------- * * ****** ****** - 4 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:10:19 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - pinned case Case: Survival heading 180 *** Operational data *** *** Environmental conditions *** Elevated weight..: 154.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 180.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.400 m Overturning stability: 1.085 over legs 2 and 3 Natural period.......: 8.669 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 16.785 1354.32 80.687 180. Wind........: 5.158 762.71 147.882 180. Dynamic.....: 4.085 578.42 141.600 180. Load / leg .............: 1 2 3 Waveload inline.(MN ): 4.148 6.318 6.318 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 79.520 81.070 81.070 Guides........hor.(MN ): 6.344 1.715 1.736 .......vert.(MN ): -13.115 84.911 83.134 .....moment.(MN.m): 1220.206 952.856 950.775 Footing.......hor.(MN ): 10.492 7.815 7.833 .......vert.(MN ): 5.207 103.172 101.396 .....moment.(MN.m): 0.000 0.000 0.000 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.295 0.295 0.295 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09

Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175


APPENDIX C

LEGLOAD RESULTS FOR NORTH SEA SAND – FIXITY

CASE

Revision A

P 11512-8175 C-1.


---------------------------------------------- * * ****** ****** - 1 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:54:04 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - fixity case Case: Survival heading 180 *** Operational data *** *** Environmental conditions *** Elevated weight..: 167.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 180.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 9: Non-linear footing restraint analysis 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.191 m Overturning stability: 1.377 over legs 2 and 3 Natural period.......: 7.111 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 16.785 1354.32 80.687 180. Wind........: 5.158 762.71 147.882 180. Dynamic.....: 2.420 342.68 141.600 180. Load / leg .............: 1 2 3 Waveload inline.(MN ): 4.148 6.318 6.318 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 79.520 81.070 81.070 Guides........hor.(MN ): 4.635 1.656 1.690 .......vert.(MN ): -0.034 84.944 83.020 .....moment.(MN.m): 1006.624 808.967 806.303 Footing.......hor.(MN ): 8.783 7.814 7.846 .......vert.(MN ): 18.291 103.209 101.284 .....moment.(MN.m): 0.000 120.562 123.103 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.295 0.295 0.295 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 C-2.


*** Non-linear footing restraint analysis data *** Restraint model: RP standard Soil type.................: SAND Internal angle of friction: 34.000 degr Soil shear modulus........: 46.000 MN/m2 Soil Poisson ratio........: 0.200 - Degree of adhesion factor.: 0.000 - in Clay Preload at footings.......: 152.900 MN Effective footing diameter: 14.000 m penetration: 0.000 m Embedment factor..........: 1.000 - Ultimate moment factor....: 1.000 - Note: Used natural period and DAF are based upon given K3.: 734. MN.m/degr *** Soil stiffness *** Foot: 1 2 3 Vertical K1 .............[MN/m]: 0.234E+04 0.234E+04 0.234E+04 Horizontal K2 .............[MN/m]: 222. 222. 222. Rotational K3 initial [MN.m/degr]: 918. 918. 918. Rotational K3 ..final [MN.m/degr]: 0.00 135. 139. Failure ratio rf .............[-]: 1.000 0.984 0.982 Iteration error ..............[%]: 0.000 0.001 0.000

Revision A

P 11512-8175 C-3.


---------------------------------------------- * * ****** ****** - 2 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:54:04 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - fixity case Case: Survival heading 210 *** Operational data *** *** Environmental conditions *** Elevated weight..: 167.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 210.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 9: Non-linear footing restraint analysis 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.215 m Overturning stability: 1.581 over legs 2 and 3 Natural period.......: 7.111 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 17.159 1381.52 80.515 210. Wind........: 5.185 766.82 147.891 210. Dynamic.....: 2.480 351.17 141.600 210. Load / leg .............: 1 2 3 Waveload inline.(MN ): 5.647 4.711 6.801 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 81.229 77.500 82.010 Guides........hor.(MN ): 3.477 3.075 1.394 .......vert.(MN ): 5.908 103.497 58.525 .....moment.(MN.m): 942.671 954.226 766.222 Footing.......hor.(MN ): 9.042 7.695 8.194 .......vert.(MN ): 24.182 121.843 76.773 .....moment.(MN.m): 32.411 79.186 138.979 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.305 0.305 0.305 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 C-4.


*** Non-linear footing restraint analysis data *** Restraint model: RP standard Soil type.................: SAND Internal angle of friction: 34.000 degr Soil shear modulus........: 46.000 MN/m2 Soil Poisson ratio........: 0.200 - Degree of adhesion factor.: 0.000 - in Clay Preload at footings.......: 152.900 MN Effective footing diameter: 14.000 m penetration: 0.000 m Embedment factor..........: 1.000 - Ultimate moment factor....: 1.000 - Note: Used natural period and DAF are based upon given K3.: 734. MN.m/degr *** Soil stiffness *** Foot: 1 2 3 Vertical K1 .............[MN/m]: 0.234E+04 0.234E+04 0.234E+04 Horizontal K2 .............[MN/m]: 222. 222. 222. Rotational K3 initial [MN.m/degr]: 918. 918. 918. Rotational K3 ..final [MN.m/degr]: 34.3 85.4 155. Failure ratio rf .............[-]: 1.000 1.000 0.974 Iteration error ..............[%]: 0.000 0.000 0.000

Revision A

P 11512-8175 C-5.


---------------------------------------------- * * ****** ****** - 3 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:54:05 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - fixity case Case: Survival heading 240 *** Operational data *** *** Environmental conditions *** Elevated weight..: 167.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 240.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 9: Non-linear footing restraint analysis 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.166 m Overturning stability: 2.844 over legs 2 and 3 Natural period.......: 7.111 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 17.018 1374.08 80.743 240. Wind........: 5.160 763.00 147.870 240. Dynamic.....: 2.465 349.08 141.600 240. Load / leg .............: 1 2 3 Waveload inline.(MN ): 6.430 4.158 6.430 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 82.193 76.258 82.193 Guides........hor.(MN ): 2.252 3.433 2.231 .......vert.(MN ): 24.672 109.138 34.120 .....moment.(MN.m): 801.432 997.271 803.545 Footing.......hor.(MN ): 8.572 7.590 8.555 .......vert.(MN ): 42.918 127.507 52.367 .....moment.(MN.m): 105.156 59.153 120.660 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.295 0.295 0.295 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 C-6.


*** Non-linear footing restraint analysis data *** Restraint model: RP standard Soil type.................: SAND Internal angle of friction: 34.000 degr Soil shear modulus........: 46.000 MN/m2 Soil Poisson ratio........: 0.200 - Degree of adhesion factor.: 0.000 - in Clay Preload at footings.......: 152.900 MN Effective footing diameter: 14.000 m penetration: 0.000 m Embedment factor..........: 1.000 - Ultimate moment factor....: 1.000 - Note: Used natural period and DAF are based upon given K3.: 734. MN.m/degr *** Soil stiffness *** Foot: 1 2 3 Vertical K1 .............[MN/m]: 0.234E+04 0.234E+04 0.234E+04 Horizontal K2 .............[MN/m]: 222. 222. 222. Rotational K3 initial [MN.m/degr]: 918. 918. 918. Rotational K3 ..final [MN.m/degr]: 119. 63.7 138. Failure ratio rf .............[-]: 0.996 1.000 0.982 Iteration error ..............[%]: 0.000 0.000 0.000

Revision A

P 11512-8175 C-7.


---------------------------------------------- * * ****** ****** - 4 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 08/10/2010 10:54:05 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 North Sea - sand - fixity case Case: Survival heading 180 *** Operational data *** *** Environmental conditions *** Elevated weight..: 154.93 MN Waterdepth.......: 106.70 m Eccentricity -X-: -2.20 m Wave height......: 24.08 m -Y-: -0.35 m Wave period......: 15.80 sec Airgap...........: 23.00 m Wave angle.......: 180.0 degr Clearance........: 9.40 m Wave theory......: Stokes-5 Support position.: 0.40 m Wave length......: 383.27 m Penetration......: 2.00 m Wave elevation...: 13.60 m Leg reserve......: 18.60 m Wind velocity....: 45.00 m/sec Footing restraint: NO Current velocity.: 1.00 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 9: Non-linear footing restraint analysis 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 2.130 m Overturning stability: 1.333 over legs 2 and 3 Natural period.......: 6.852 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 16.785 1354.32 80.687 180. Wind........: 5.158 762.71 147.882 180. Dynamic.....: 2.208 312.71 141.600 180. Load / leg .............: 1 2 3 Waveload inline.(MN ): 4.148 6.318 6.318 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 79.520 81.070 81.070 Guides........hor.(MN ): 4.442 1.640 1.668 .......vert.(MN ): -2.305 79.502 77.732 .....moment.(MN.m): 973.950 783.727 781.495 Footing.......hor.(MN ): 8.590 7.806 7.832 .......vert.(MN ): 16.021 97.767 95.997 .....moment.(MN.m): 0.000 127.494 129.353 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.295 0.295 0.295 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 4.460 4.460 4.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 C-8.


*** Non-linear footing restraint analysis data *** Restraint model: RP standard Soil type.................: SAND Internal angle of friction: 34.000 degr Soil shear modulus........: 46.000 MN/m2 Soil Poisson ratio........: 0.200 - Degree of adhesion factor.: 0.000 - in Clay Preload at footings.......: 152.900 MN Effective footing diameter: 14.000 m penetration: 0.000 m Embedment factor..........: 1.000 - Ultimate moment factor....: 1.000 - Note: Used natural period and DAF are based upon given K3.: 734. MN.m/degr *** Soil stiffness *** Foot: 1 2 3 Vertical K1 .............[MN/m]: 0.234E+04 0.234E+04 0.234E+04 Horizontal K2 .............[MN/m]: 222. 222. 222. Rotational K3 initial [MN.m/degr]: 918. 918. 918. Rotational K3 ..final [MN.m/degr]: 0.00 149. 151. Failure ratio rf .............[-]: 1.000 0.977 0.976

Iteration error ..............[%]: 0.000 0.000 0.000

Revision A

P 11512-8175


APPENDIX D

ATTACHMENT FROM [REF 4] FOR USE IN SNAME

CLAY ASSESSMENT

Revision A

P 11512-8175 D-1.


Revision A

P 11512-8175


APPENDIX E

LEGLOAD RESULTS FOR GULF OF MEXICO – CLAY

CASE

Revision A

P 11512-8175 E-1.


---------------------------------------------- * * ****** ****** - 1 -- L E G L O A D -- ** ** * * -- -- -- * ** * ****** * -- -- Version: 5.13 -- * * * * -- -- HOF 22/11/2010 10:43:55 -- * * ****** ****** -- -- MARINE STRUCTURE CONSULTANTS bv Pob 687 -- SCHIEDAM --- HOLLAND -- ---------------------------------------------------------------------- Unit: CJ62 GoM - clay case Case: Survival heading 180 *** Operational data *** *** Environmental conditions *** Elevated weight..: 167.93 MN Waterdepth.......: 82.50 m Eccentricity -X-: -2.20 m Wave height......: 18.92 m -Y-: -0.35 m Wave period......: 16.00 sec Airgap...........: 17.50 m Wave angle.......: 180.0 degr Clearance........: 6.80 m Wave theory......: Stokes-5 Support position.: 44.00 m Wave length......: 367.44 m Penetration......: 45.60 m Wave elevation...: 10.70 m Leg reserve......: 4.70 m Wind velocity....: 50.00 m/sec Footing restraint: NO Current velocity.: 1.50 m/sec The following options were ON: 1: User defined wave parameters 2: User defined current type and profile 3: User defined wind profile 4: Load factors 5: Marine growth 9: Non-linear footing restraint analysis 10: Extended FE-solver was used 14: User defined time step *** Results *** Platform deflection..: 1.730 m Overturning stability: 1.771 over legs 2 and 3 Natural period.......: 6.014 sec Total load Load Moment Level Angle ---------- [MN] [MN.m] [m] [degr] Wave/current: 14.933 1537.19 102.939 180. Wind........: 5.762 926.90 160.862 180. Dynamic.....: 1.305 202.88 155.500 180. Load / leg .............: 1 2 3 Waveload inline.(MN ): 3.769 5.582 5.582 transverse.(MN ): 0.000 0.000 0.000 level.(m ): 102.078 103.230 103.230 Guides........hor.(MN ): 4.407 1.418 1.459 .......vert.(MN ): 13.982 77.895 76.052 .....moment.(MN.m): 730.587 568.166 567.262 Footing.......hor.(MN ): 8.176 6.914 6.953 .......vert.(MN ): 39.879 103.741 101.898 .....moment.(MN.m): 377.252 365.429 368.977 *** Leg and hull data *** Leg No: 1 2 3 Coordinates -X-...(m ): 35.800 -17.900 -17.900 -Y-...(m ): 0.000 -31.000 31.000 Orientation ......(degr ): 0. 0. 0. Specific diam. D (m ): 16.000 16.000 16.000 CD (- ): 0.295 0.295 0.295 CM (- ): 0.025 0.025 0.025 CA (- ): 0.013 0.013 0.013 Moment of inertia.(m4 ): 26.440 26.440 26.440 Specific weight...(kN/m ): 96.20 96.20 96.20 Specific buoyancy.(kN/m ): 25.20 25.20 25.20 Can subm. weight..(MN ): 12.460 12.460 12.460 Can rot.stiffness.(MN.m/deg): 0.100E+09 0.100E+09 0.100E+09 Total leg length..(m ): 175.3 175.3 175.3

Revision A

P 11512-8175 E-2.


*** Non-linear footing restraint analysis data *** Restraint model: RP standard Soil type.................: CLAY Undrained shear strength..: 63.700 kN/m2 Soil shear modulus........: 61.200 MN/m2 Soil Poisson ratio........: 0.500 - Degree of adhesion factor.: 1.000 - in Clay Preload at footings.......: 168.000 MN Effective footing diameter: 17.840 m penetration: 1.450 m Note: Footing is assumed fully embedded Note: Suction (uplift resistance) is available Embedment factor..........: 1.200 - Ultimate moment factor....: 1.428 - Note: Used natural period and DAF are based upon given K3.: 0.388E+04 MN.m/degr *** Soil stiffness *** Foot: 1 2 3 Vertical K1 .............[MN/m]: 0.437E+04 0.437E+04 0.437E+04 Horizontal K2 .............[MN/m]: 0.291E+04 0.291E+04 0.291E+04 Rotational K3 initial [MN.m/degr]: 0.485E+04 0.485E+04 0.485E+04 Rotational K3 ..final [MN.m/degr]: 764. 743. 757. Failure ratio rf .............[-]: 0.979 0.981 0.979 Iteration error ..............[%]: 0.000 0.001 0.000

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P 11512-8175 E-3.



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P 11512-8175 E-5.



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P 11512-8175 E-8.



ISO 19905-1 BENCHMARK STUDY - ASSESSMENT IN … · 3100 AR Schiedam, the Netherlands Telephone +31...

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Transcript of ISO 19905-1 BENCHMARK STUDY - ASSESSMENT IN … · 3100 AR Schiedam, the Netherlands Telephone +31...