This course will be available in January semester. The material to be presented  might be slightly different as to be updated every semester to include the latest information. This course  is focused more on design aspects of steel jacket template type platforms.

• To understand and able to describe the design process of fixed offshore structures, the requirement of environmental data, site investigation, method and type of analysis, material behavior subjected to cyclic loading, interpretation of analytical results.

• To be able to use various codes, develop design criteria, conduct a preliminary study of offshore structural systems to investigate the advantages and disadvantages of structural configuration  and weight; material selection; joint connections.

• To fully aware to pile problem affected by seabed soil condition, fatigue life of tubular joints, overstressed steel sections due to live load or environmental forces, compatibility at interface points of jacket and piles, on-bottom stability, topsides area requirement appurtenances,  dynamic amplification factor; etc.

• To be able to prepare the requirement of input data for various detail analyses using the available program package for further detail analysis at work, to develop t-z, p-y and Q-z curves based  on API RP 2A, interpret the computer outputs and take remedial actions.

• To be able to perform local steel design calculations such as hydrostatic check, boat landing design, crane pedestal, deck beams, mudmat design, etc.

None.

1. Introduction:

a. Development history

b. Technologies

c. Operational consideration (WHP, QP, CPP, etc.), environmental consideration, site investigation, safety and others

2. Description of platform structures:

a. Monopod and cluster platforms:

i. Single caisson structure with topside

ii. Braced monopod with pile foundation and topside

iii. Cluster platform: multi-conductor cluster

b. Jacket template type platforms:

i. Topsides:

- Deck flooring system: pancake and inter-costal beam system

- Framing systems: open or braced

ii. Jacket:

- Space braced-frame structure

iii. Foundation system:

- Mudmat

- Grouted or non-grouted piles: main, skirt and insert

c. Compliant tower platforms

i. Topsides

ii. Jacket with or without mooring lines

iii. Base structure

d. Concrete Gravity Platforms

i. Topsides

ii. Concrete substructure: column

iii. Foundation system: concrete base consists of compartment (tanks)

e. Tension Leg Platforms (TLP)

i. Floating structure: deck, column, and hull

ii. Tendon (tether) system

iii. Foundation system: base structure with tension piles

3. Appurtenances to support platform operation:

a. Mezzanine deck

b. Pedestrian and utility bridges

c. Modules: living quarter, switchgear building

d. Boat landing, barge bumper with swing ropes, and heliport for personnel  transportation

e. Risers and pipelines as product lines, riser protectors

f. Flooding and grout lines

g. Corrosion protection: sacrificial anodes, impressed current, steel thickness allowance  at splash zone.

h. Crane pedestal, access platform and boom rest (cradle) for deck crane

i. Supporting structure for survival capsule, firewall for personnel safety besides other  safety means (life raft, life jacket, ring buoy).

j. Telecommunication tower for antennas and parabolic disks for communication at radio room.

k. Gutter, drains, sump caisson, coaming, flare boom or tower, vent stack for either water or air pollution control.

4. Design aspect of a jacket template platform

a. Preliminary design of topsides:

i. Platform topsides area requirement

ii. Local and global design using blanket live load: applied load factors, tributary loading pattern, loading distribution based on flexural stiffness ratio, maximum allowable deflections and displacements, allowable stresses

iii. Elevations of bottom elevations of lower (cellar) deck, upper (main) deck, sump (sub cellar) deck and mezzanine deck: air gap, equipment and piping

b. Preliminary design of jacket:

i. Site characteristics: water depth, mean sea level (MSL), chart datum, tidal height, design wave height, marine growth, properties of air and sea water, splash zone, rainfall intensity

ii. Elevations of top of jacket and intermediate horizontal framings

iii. Selection of batter of jacket leg: piling efficiency and jack-up rig considerations

iv. Preliminary member sizing based on jacket geometry: kl/r<80 and D/t <60

c. Preliminary of piles (main, skirt and insert piles):

i. Environmental and gravitational loading magnitudes, soil strength properties, available hammer driving energy, minimum thickness of pile, size of annulus gap, tubular size, jack up spud can effect

d. Preliminary design of appurtenances:

i. Design of boat landing single and split-level elevations: tidal height and type of supply barge

ii. Flare boom orientation and location: wind direction and operational consideration

iii. Mudmat: seabed soil condition, weather window and installation procedure

iv. Flooding and or grout lines: size of jacket, maximum hook height of derrick barge crane, stiffness of platform

5. Structural Modelling of fixed offshore platforms

a. Integrated structural model using one-dimensional (line) element

i. Monopod, braced-monopod and cluster platforms

ii. Jacket template platform: topside, jacket and pile (linearized model for dynamics)

iii. Compliant tower platform with or without mooring lines

b. Integrated structural model using two-dimensional (shell and plate) element

i. Concrete gravity platforms: topside, substructure and foundation

c. Integrated structural model using one and two dimensional elements

i. Tension Leg Platforms

d. Computer laboratory: using Sacs software package to develop jacket template structural model (flooded/non-flooded members) including boat landing, barge bumper, risers, sump caissons, conductors, non-modelled structural components: topsides and mudmat plating with or without stringers, sacrificial anodes, pad eyes, gratings, handrails, stairways, crown shims, etc.

6. Sea states

a. Wind: wind distribution versus height, location and ground surface, wind rose, surveys and measurement

b. Wind generated waves:

i. Terminology

ii. Wave theories: small amplitude (linear/Airy) and finite amplitude wave (Stokes), Stream function wave and diffraction, laboratory experiment

iii. Drag, inertia and lift coefficients: Reynolds numbers associated with fluid flows, Keulegan-Carpenter Number, roughness to diameter ratio (friction)

iv. Regions of applicability of wave theory

c. Tide: hydrostatic and hydrodynamic pressures

7. Design loads (gravity loadings and environmental forces)

a. Gravity loading:

i. Dead (gravitational) loads: structural self-weight and appurtenances, dry weight of mechanical equipment, vessels, piping, electrical equipment, instruments, modules, etc.

ii. Live loads: blanket at unoccupied area and equipment content (supply and storage loads)

iii. Operational loads: pedestal crane lift load, work-over rig hook and set-back loads, helicopter landing impact loads, boat berthing impact load, thermal load due to flare

b. Environmental forces

i. Vertical force: buoyancy

- Hydrostatic pressure during still water

- Hydrodynamic pressure due to wave and tide

ii. Horizontal forces:

- Sustained wind force: shape coefficients, height factor, Strouhal Number

- Wave and current force: Doppler’ effect, conductor shielding factor, wave kinematics factor, current blockage factor, classification for wave force method (Morison or Diffraction (or Froude-Krylov) analysis)

iii. Force on the inclined member

8. Aspects of structural analysis:

a. Design criteria: strength and serviceability criteria

i. Strength and serviceability criteria: conditions of maximum stress and maximum deflection or frequency

ii. Loading scenarios: load cases and load combination, storm (typhoon) and operating (monsoon)

iii. Maximum pile-head lateral deflections: large displacement (P-Δ) effect, serviceability criteria

iv. Material selection with respect to mechanical strength properties (yield stress, ultimate stress, rupture (breaking) stress, lamellar tearing stress), Charpy Vþnotch criteria, thru thickness test (Z test)

b. Static or dynamic in-place analysis

i. Determination of fundamental period of jacket template platform

ii. Compatibility condition at pile-head joints: brief theory of substructure technique, tolerance of pile head displacements for convergence criteria, pile head forces

iii. Stresses at joint face: cut-off bending moments and shear forces (if member offset is not modelled)

9. Code checks:

a. Brief description of codes, standards and specifications, used in oil and gas industry practice (DNV 1977 Appendix B and C, API RP 2A 21st Ed. ‘WSD’, AISC 9th Ed. ‘ASD’, AWS D1.1 2004, API 2C 6th Ed.)

b. Member code checks: interaction ratio less than one

c. Joint code check: joint classification, types and geometric notation, punching shear check, nominal loads in the brace

10. Design of offshore platform pile foundation:

a. Single/group driven or grouted piles, scour effect

b. Pile target penetration depth: open and close ended pile bearing capacity, factor of safety

c. Pile stress analysis for in-place and seismic: soil-pile interaction, p-y, t-z, and Q-z curves (static and cyclic soil data)

d. Pile make-up: selection of hammer, pile add-ons and initial pile length, pile initial settlement, pile drivability analysis

e. Bearing capacity and stability of shallow foundation: Concrete Gravity Platform, on bottom stability of jacket (design of mudmat)

11. Deterministic fatigue analysis (optional)

a. Selection of wave blocks

b. Stress analysis due to wave

c. Stress concentration factors for tubular joints: Kuang, Smedley, Kellog, etc.

d. Hot spot stress: simple and stiffened tubular joints

e. Cumulative fatigue damage ratio: Palmgren-Miner rule, S-N curves

12. Earthquake analysis (optional)

a. Mass: equipment and content, structural steel, non-steel mass, marine growth, entrapped water mass, added mass

b. Selection of master and slave DOF’s

c. Response spectrum method: response spectra

d. Combination of responses: modal response combination (CQC method) and directional response combination (SRSS method)

e. Stress combination: gravitational stress and seismic induced stresses for member and joint

None

Lecture notes and selected papers provided by instructor.

1. Introduction to Offshore Structures: Design, Fabrication, Installation, by W.J. Graff, Gulf Publishing Company, Houston

2. Offshore Structural Engineering, T.H. Dawson, Prentice-Hall 1983

3. Applied Offshore Structural Engineering, by Teng H. Hsu, Gulf Publishing Company,

4. 'Offshore Structures', vol. 1, 'Conceptual Design and Hydromechanics', vol. 2, ‘Strength and Safety for Structural Design’, by Clauss, G. et al., Springer-Verlag 1992.

5. The Structural Design of Offshore Jackets, by Visser, W., Marine Technology Directorate  1994

6. Planning and Design of Fixed Offshore Platforms, by McClelland, B. and Reifel, M. D., Van Nostrand Reinhold 1985

7. Design of Pile-supported Steel Jacket Platforms, by Jerome J. Connors, Amir S. Azzouz and S. Shyam Sunder, Dept. of Civil Engineering, Massachusetts Institute of Technology, July 1981

8. Dynamics of Fixed Marine Structures, by Barltrop NDP & Adams AJ, Marine Tech. Directotate 1991

9. Mechanics of Wave Forces on Offshore Structures, Sarpkaya T. and Isaacson M., Van Nostrand Reinhold Company, New York, 1981

10. Design Guides for Offshore Structures Offshore Pile Design, by Ed. Piere Le Tirant, Edition Technip 1992

11. Construction of Marine and Offshore structures, 3rd Ed, by Ben C. Gerwick Jr., CRC Press, 2007.

12. Design of tubular joints for Offshore Structures, Vol 1, UEG 1985

13. Offshore Structure Modelling, by Chakrabarti S, World Publishing Pty. Ltd. 1994

14. Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms – Working Stress Design, API RP 2A-WSD, 21th Ed., 2000

15. Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms – Load Resistance Factor Design, API RP 2A-LRFD, 1st Ed., July 1, 1993

25. Rules for the Design, Construction and Inspection of Offshore Structures, Det Norske  Veritas (DNV), Oslo, Norway, Appendix B an C.

16. Manual of Steel Construction – Allowable Stress Design, AISC 9th Ed.

17. Manual of Steel Construction – Load Resistance Factor Design, 1st Ed.

18. Building Code requirements for minimum design loads in buildings and other structures, American National Standard Institute (ANSI) A58.1-1997

19. Formulas for Stress and Strain, 6th Ed, RJ Roark & WC Young, McGraw-Hill International Book Coy 2000

20. Guide for the Design and Construction of Fixed Offshore Concrete Structures, ACI 357R-84, (re-approved 1997)

1. Journal of Petroleum Technology

2. Journal of Offshore Mechanics and Artic Engineering, Transaction of ASME

3. Proceedings of Offshore Technology Conference (OTC), Houston, USA

4. American Oil & Gas Reporter

5. Applied Ocean Research

Others: 

1. Offshore Engineer, www.offshore-engineer.com

2. World Oil, www.gulfpub.com

3. Offshore, www.offshore-mag.com

This 3-credit course 3(3-0) will last for four months and consists  of three hours of lecture per week. On top of that, for each equivalent lecture hour, the students have  to spend from 3 to 6 hours of self-study for homework, studying lecture notes and textbooks, reading  research papers.

Lectures, in-class exercises, homework, presentation.

The final grade will be computed according to the following weight distribution: 

tutorial assignments (30%):

analytical concept and solution; mid-semester report and presentation of 

case study (30%):

problems in design; final semester report and group presentation of project (40%): 

design of offshore platforms