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OFFSHORE STRUCTURAL DESIGN

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Introduction

• Define the subject matter• Design philosophy;

Taguchi’s theory of robust design; Deming’s principles of quality control; Quality Function Deployment; Design for Manufacture; Concurrent Engineering; etc.

• Accuracy of Factor of Design (LRFD v WSD)• LEAN APPROACH TO DESIGN• R4D – Research for Design• AEE - Advanced Engineering Environment

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Generic mechanical engineering design process

START

Recognition of a need

Definition of the problem

Design synthesis

Evaluation of preliminary designs

Detailed design

END

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OFFSHORE FIELD DEVELOPMENT PLAN

ACQUIRE

EXPLORE & APPRAISE

DEVELOP

OPERATE

DECOMMISSION

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Feasibility Studies

Preliminary Design

Final Design

Reservoir Management

Drilling & Well Plans

FacilitiesPlatform

Offtake

Economics

External Constraints

Environmental Criteria

Offshore Development Design Spiral

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DESIGN WORK;ancient structures, ancient thinking

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DESIGN WORK;recent past offshore structures

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DESIGN WORK;modern thinking

Detailed Design

Design Synthesis

AEE

Need Recognition

LEAN DESIGN

R4D

Evaluation&

Selection

ProblemDefinition

Preliminary Designs

Continuous Learning

CL

ASS

ST

AN

DA

RDTEAM

WORK

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OFFSHORE STRUCTURESMajor Classes of Loads Considerations

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TUBULAR JOINT DESIGN

• Design Methods LRFD; WSD

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LRFD DNV OS C101

• Load & Resistance Factor Design:deterministic based, data gathered by observation of model testing or monitoring of full size structure

• Limit States: ULS, FLS, ALS, SLS

• Structural element design Ref. DNV OS C401

• Fatigue Ref. DNV RP C203

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WSD DNV OS C201

• Working or Allowable Stress Design:deterministic based, data gathered by observation of model testing or monitoring of full size structure; sensitive fatigue analysis necessary

• Joints to be designed to minimise stress concentrations and reduce complex stress flow pattern

• Structural element Ref. DNV OS C401

• Fatigue Ref. DNV RP C203

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Summary Offshore Engineering

• Offshore engineering is a process of group activity and it brings together a large number of expertise in order to fulfil it’s objectives.

• The aims of structures & structural element design are:

1. Sustain loads2. Maintain acceptable safety3. Posses adequate durability