COMPOSITE CONSTRUCTION TECHNOLOGY FOR FLOATING AND SUBSEA STRUCTURES

Obiettivo

Offshore hydrocarbon production is increasingly located at sites in very deep water and in extremely hostile environments, in particular Arctic and other areas subject to sea ice. Floating production or drilling facilities represent an important solution to the engineering problems.
The traditional materials for such offshore structures are stiffened steel plate or reinforced or prestressed concrete. Stiffened steel plate is a very expensive, time comsuming, problematic and an awkward form of construction. Concrete structures are relatively heavy thereby reducing their payload capacity; they also suffer from abrasion when subjected to ice attack. Steel-concrete-steel construction however uses the different physical properties of the two materials appropriately, and can be constructed in a very simple, cheap and robust manner.
The aim is to prepare guidance to enable practising engineers to produce designs using a steel-concrete-steel sandwich as the construction material.
The project has identified that existing knowledge on the flexural behaviour of steel-concrete-steel flat panels is good, but that less knowledge exists on other failure modes (ie. shear failure of beams, buckling of the steel plates, failure of the shear keys). A variety of shear keys have been used and their behaviour and the practicality of their use in industrial production is known. The significant cost benefit of using headed studs as the method of shear connection has been demonstrated. Consequently, understanding the behaviour of stud shear connectors within the steel-concrete-steel specimens has been one of the primary objectives of this project.
The project will develop design guidance and substantiated costings. A laboratory test programme will be undertaken to cover gaps in existing knowledge and to extend data into areas useful for the offshore production of hydrocarbons. Simultaneously an existing non-linear computer program will be enhanced to model the failure mechanism of the steel-concrete-steel sandwich.
Designs of existing facilities will be reworked using steel-concrete-steel as the construction material.
Detailed descriptions of the individual activities follow.
DATA REVIEW
Laboratory test data, theoretical considerations, existing and potential new applications will be investigated using standard literature review techniques. The review will identify the uncertainties to be covered by this project.
LABORATORY TEST PROGRAMMME
The test programme will be defined by the data review. It will be designed to develop steel-concrete-steel sandwich technology into those areas identified by the hydrocarbons industry asbeing relevant in the medium term.
The programme will concentrate on cylindrical components (representing the legs of floating facilities) and on the in-plane behaviour of flat panels. The behaviour of the joints between panels will also be investigated. Cylinders of up to 1800 mm diameter will be tested in a rig capable of developing 6000 tonnes axial load. The flat panels will model bulkheads of up to 1000 mm thickness.
Parameters to be investigated will include the relative contributions of the steel and the concrete, and the eccentricity of the applied loads. The sensitivity of the material to cyclic loadings will be determined, and the performance of lightweight concrete will be compared to that of normal concrete.
ANALYTICAL WORK
A general triaxial concrete material model will be selected and incorporated into an existing non-linear program. The program will be validated (not calibrated) against the results of the test programme.
DESIGN TOOL
The enhanced program will be usedto produce design curves for the full range of parametric variations including steel and concrete thicknesses and strengths, the nature of any shear keys, and the applied loading characteristics.
These curves will be formulated into a design program capable of being used by a practising engineer. Full design documentation will be produced.
DESIGN WORK
Recent existing offshore hydrocarbon facilities will be redesigned using steel-concrete-steel as the construction material. The redesign will meet the same design premise as the original design, although reconfigurations will ensure that the new design uses the full benefits of steel-concrete-steel construction.
COSTING ACTVITIES
The cost of steel-concrete-steel sandwich construction produced at an industrial scale will be determined. The costs will be verified by fabrication and construction companies. These costings will then be applied to the new design to stand in direct comparison with the known cost of the original design.

Programma(i)

ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989

Argomento(i)

1.9 - PRODUCTION SYSTEMS

Invito a presentare proposte

Data not available

Meccanismo di finanziamento

DEM - Demonstration contracts

Coordinatore

Billington Osborne Moss Engineering Ltd (BOMEL)

Contributo UE

Nessun dato

Indirizzo

LEDGER HOUSE FOREST GREEN ROAD FIFIELD
SL6 2NR MAIDENHEAD
Regno Unito

Costo totale