Catamaran Float-Over Barge Preloading for Topsides Stress Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The challenge in installing topsides on deepwater Spar platforms and other offshore structures lies in the high loading conditions and material requirements due to wave-induced stresses on catamaran float-over systems, which necessitate increased member sizes and weight, leading to higher costs and inefficiencies.

Innovation Solution

A method and system that preloads float-over barges with an upward lifting force to counteract the sagging bending moment of the topsides' self-weight, reducing stress on members and allowing for lighter, more efficient construction by positioning ballast and bracing members to distribute loads more effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If catamaran float-over system is used to install topsides on deepwater Spar platforms, then the installation can be performed in deep water with float-over capability, but wave-induced stresses on separated barges cause high loading conditions requiring increased member sizes and weight

Engineering Contradiction:

Improvefloat-over capabilityVSAvoidmember weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent applies counterweight principle by positioning ballast on the barges to create upward lifting forces that counteract the sagging bending moments caused by wave-induced stresses. This reduces the net loading on the topsides and grillage members, allowing for lighter member weights while maintaining structural integrity during float-over operations

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent changes the loading parameters by introducing preloading forces through ballast positioning. This modifies the stress state in the grillage members from pure sagging bending moments to a combined state with upward counteracting forces, reducing the required member sizes and weights

Inventive Principle:

Principle #35Parameter changes

2Strength

If member sizes are increased to withstand wave-induced loads on catamaran system, then structural strength is improved, but material requirements and construction costs increase

Engineering Contradiction:

Improvestructural strengthVSAvoidmaterial quantity

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

By positioning ballast to create upward lifting forces that counteract wave-induced sagging moments, the patent reduces the net stress on structural members. This allows maintaining required structural strength with reduced member sizes and material quantities

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent applies preliminary preloading to the catamaran system by positioning ballast before float-over operations. This pre-positioning of counteracting forces prepares the structure to withstand wave-induced loads more efficiently, reducing the material required while maintaining strength

Inventive Principle:

Principle #10Preliminary action

3Power

If traditional multi-lifting method is used for topsides installation, then lifting capacity limitations of available HLV are addressed, but steel weight per unity area of topsides increases

Engineering Contradiction:

Improvelifting capacityVSAvoidtopsides steel weight

Core Design Contradiction:

PowerVSWeight of moving object

Solution Approach 1:

The patent merges the topsides installation with the float-over barge system, combining transportation and installation operations. This eliminates the need for multiple separate lifting operations by HLV, allowing the topsides to be installed as a single integrated deck while reducing steel weight per unity area

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces the material and weight requirements for the topsides and grillage system, resulting in significant cost savings and improved structural integrity without increasing member sizes, enabling efficient float-over installations on offshore structures.

Implementation Method 1

adding a ballast to the barges to at least partially counteract a sagging bending moment caused by the weight of the topsides

Methodology Applied

Scientific EffectSagging bending moment:

Implementation Method 2

adding a ballast to the barges to at least partially counteract a sagging bending moment caused by the weight of the topsides

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP2389311B1Preloading to reduce loads and save steel on topsides and grillage of catamaran systems

Publication Date: 2014.10.29 TECH FRANCE SA

Figure 1A~1B
Figure 2A~2B
Figure 3A~3D

AI summary

The present invention reduces loads and saves steel on topsides and grillage of a catamaran system by creating an upward, lifting force from a barge to the topsides to offset a sagging bending moment of the self-weight on the topsides during transportation. The present invention can reduce the span of the supports on the topsides on the catamaran float-over barges and move the reaction forces toward inner edges of the float-over barges. The upward force can cause a reduction of stress on the topsides' and grillage's members caused during the topside offloading and transportation. The stress reduction can result in the members withstanding the additional dynamic load caused by a catamaran system without increasing member sizes adequate for an offloading operation. The reduction results in a significant savings, given the size of a typical topsides for a Spar hull or other offshore structure.