Sesam - Efficient Engineering of Topside Structures

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Pål Dahlberg, Sesam Principal Sales Executive, DNV Software10 May 2011

SesamTM

40 years of success

Efficient engineering of topside structures

Presenter

Presentation Notes

Alternative title slide

© Det Norske Veritas AS. All rights reserved.

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Efficient engineering of topside structures Save man-hours and increase quality

by using the latest available capabilities in concept technologies for- Structure modelling- Loads & Environment modelling- Forces, stresses, deflections- Local models in global model- Beam code checking- Design iterations including redesign of

members- Plate code checking- Fatigue (separate presentation)

Wave or wind induced


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Common challenges in design


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The importance of the Sesam design loop

40-60% of engineering time often spent in evaluation

How fast can you do it over again?


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Closing the design loop – our strength

Efficient data transfer from initial modelling through analysis, results processing and code checking- “How long time does it take from modelling to first result?”

Efficient member code check iterations- “What is the effect of modifying a section or code check

parameters without re-running complete analysis?”

Efficient update of model based on code check iterations- “How long time does it take to re-generate a code

check-report based on a full re-run of model and analysis”


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How can Sesam help you –Making a model in GeniE

Structure


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Structure modelling Easy to facilitate the range from small to large and complex


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GeniE uniqueness – structure modelling Always a consistent concept model – made for frequent design changes

- Analysis models (FEM) derived from the concept model- Beams and plates always connected, can be disconnected by use of s.el. technique


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GeniE uniqueness - combined beam/shell models Faster modelling

- Stiffeners selected from libraries- No need for calculation and evaluation of

effective flange- No lumping of loads- No doubts – model structure as is- Always a consistent topology

More accurate results- No simplified assumptions on effective flange

and lumping of loads- Better visual verification of model and results

Faster and easier re-analysis and optimization- Easy change of beam profiles from libraries- Plate thickness changed without changing

properties for all stiffeners- Easy to change geometry, stiffener arrangement

and other properties- Easy to add new stiffeners or other details

(brackets, holes etc.)


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GeniE uniqueness – structure modelling Parametric modelling – define variables in script files

5.E074.23E07


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GeniE uniqueness – structure modelling Same system – offshore and maritime

- Fixed structures, semi’s, FPSO’s, Spar, TLP- Tankers, containership, bulk, +++


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GeniE uniqueness – structure modelling Combine detailed models in

a global model

FE shell

FE beam

Plates

Beam


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GeniE uniqueness – structure modelling Local models

- Easy to go from global to many local models – all are based on the same concept model


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How can Sesam help you –Making a model in GeniE

Loads


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Load application Easy to include load sources from structural mass (gravity and accelerations),

equipments, manually defined loads, rule based loads (compartment loads) and temperature loads


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GeniE uniqueness – load application Easy to define compartment loads

- Content and filling degree is enough


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GeniE uniqueness – load application Acceleration loads – multiple choices

- Constant and varying acceleration – different accelerations on various parts of structure

Lower level loads from mass x acceleration (x & z-dir)

Upper level loads from mass x acceleration (z-dir)

Rotational accelerationHarmonic induced wave

motion


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Topsides/modules on jackets or floaters Topside on Jackets

- All is done inside GeniE- Focus of this presentation

Topside on Floaters- Opt. 1 - Integrated: Results from HydroD

(hydrodynamic frequency or time domain analysis) imported into GeniE

- Opt. 2 - No load transfer: Accelerations and deflections are computed in HydroD and used as basis for load-cases in GeniE


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Floaters – frequency domain Waves give deformations and stresses in topsides and modules


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Floaters – frequency domain Waves give deformations and stresses in topsides and modules

- These must be converted to deterministic before import to GeniE- Our utility tool Prepost is used for this purpose


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Floaters – optionally no automatic load transfer Deformations and accelerations used to define load cases in GeniE

- Accelerations constant or centripetal (from HydroD)- Deformations from global structural analysis (used as prescribed displacements in GeniE)

Sp1: 2mm

Sp2: 3mm

Sp3: 5mm

Sp4: 2mm

CentripetalAcceleration


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Reporting All reports can be reproduced and automatically recreated

- The report generation is scripted- Text, html, Excel(xml), Word(xml)

The user decides the content- Structure- Properties- Masses- Loads- Analysis (FEM) results- Frame code check- Plate code check


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Demo-time Make a local shell joint in a topside model


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Demo case – The model A traditional topside model build from beams


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Demo case – The loads A combination of equipment and acceleration loads


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Demo case – The results Viewing results in plug-in component for online presentation purposes


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Demo case – Deformations at selected joint The selected joint will be converted to a shell model

- Beam model: Max deformation is 3.6 mm


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Demo case – Deformations at selected joint The joint is now a shell model part of the global model

- Combined beam and shell model: Max deformation is 3.6 mm


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Demo case – Deformations at selected joint Consistency between beam and shell elements


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Demo case – The results Viewing results in plug-in component for online presentation purposes


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Demo case – speed! Question becomes – how long time does it take

to convert the beam joint to a shell model and re-run analysis?- 1 day- 1 hour- 30 min?- 5 min?- 4 min?

You can start your stop watches now- …..and not using a predefined special purpose build

script for this case….

http://www.online-stopwatch.com/full-screen-stopwatch/


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Demo case – add details Add brackets


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How can Sesam help you –First assessment in GeniE


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Efficient engineering – typical steps First assessment

- Forces, stresses and deflections

Code checking- Check against prescriptive standards

Member re-design- Evaluate the effect of modifying section

properties or code check parameters- Often many attempts – depends on the

engineer’s experience

Design iteration- A complete re-run of all to document the re-

design


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Beam forces and stresses Forces and stresses in 2D view as well as tabular


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Beam forces and stresses Force envelope Stress envelope


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Beam deflections – 3D view Standard 3D deformation view Using the option to compute beam

deflections without increasing number for finite elements (absolute deflections)


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Topside – 3D beam deflection view The effect of adding cubic deformations

With cubic deflection

Linear deflection ≈ deformation view


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Beam deflections – 2D view Dy, Dz and Defl = sqrt(Dy^2 + Dz^2)

Per load-case(s)

Envelopes

Worst condition

Relative deflections


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Beam deflections – tabular report 3 results are reported

- Beam length (flexible length)- Deflection (deflections & rotations) - relative- DELTA = Flexible beam length/Deflection- 5-11 points may be reported per beam- All positions or worst positions- Per load-case or envelopes (scan)


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Topside – check deflection ratio against AISC levels AISC: Allowable deflection ratio 180, 240, 360 and scanning all load cases


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Excellent design – a real case scenario Part of a super-element analysis


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Topside – all in one view You decide what you want to see


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How can Sesam help you –Beam code checking in GeniE


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Code checking in GeniE - members Supporting

- API WSD 2002/AISC ASD 2005- API WSD 2005/AISC ASD 2005- API LRFD 2003/AISC LRFD 2005- NORSOK 2004/Eurocode 3 1993- ISO 19902 2007/Eurocode 3 1993- DS 412/449


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Easy to create capacity members Members may be defined using complete structure or sub-sets

- Global default buckling lengths decided by the engineer

Buckling length? Buckling length?

Buckling length?


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Document code check results

Graphically – complete model


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Document code check results

Graphically – parts of structure only


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Report code check results Print out using filters Loadcases

- All- Worst- User defined

Positions- All- Worst

Utilisation factor- All- Above- Below

Members- All- Current selection


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Report code check results Example on layout


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Efficient redesign of members Redesign (“design iterations”)

- Step1: Preliminary results when modifying section, material, stiffener spacing or buckling length parameters- Note: The loads and stiffness

are not updated- Step2: Commit changes to model- Step3: Re-run analysis and code

check- Reports may be automatically

re-created


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Redesign – single members Select a capacity member for redesign

Modify parameters- Preliminary results automatically computed


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Redesign – single members Look at all details (Full Table)

- Shown with colour coding


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Redesign – re-run all The “Run All” command will

- Update structure from members- Run analysis- Generate code check loads (positions)- Execute code check


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Redesign – multiple members Select capacity members for redesign

Modify parameters- Preliminary results automatically computed


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Redesign – segmented beams Single or multiple


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Redesign – segmented beams Before and after


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How can Sesam help you –Plate code checking in GeniE


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Code checking of stiffened panels Create panels

- Panels are independent of analysis and finite element mesh

Three different options to define panels- Min Box finds the smallest idealised rectangular

panel possible enclosing the possibly non-rectangular structural region

- Max Area Moment is an alternative algorithm finding the major axis based on calculation of area moment of inertia of the surface. This algorithm will also work for irregular panel shapes

- CSR Tank Default is the algorithm usually used when doing a CSR Tank (PULS) code check

Min Box

Max Area Moment


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Code checking of stiffened panels – ships and offshore Code checking according to PULS (DNV RP-C201.2)

- Linear and non-linear


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Code checking of stiffened panels - offshore Yield check of plates – based on membrane stress

- Includes a safety factor S


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Code checking of stiffened panels


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Code checking of stiffened panels Demo case

- PULS non-linear on stiffened panel- Simplified yield check of plates in stiffened panel (membrane stresses)


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How can Sesam help you –Multiple analysis in GeniE


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Multiple analysis Multiple analysis in same project

- E.g. Lifting, transport, in-place- Varying parameters

- Structure- Boundary conditions- Load cases

The “master” model

Lifting Condition Transport Condition In_place Condition


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Multiple analysis – graphic results Different results at your finger-tips

- Bending moments shown

Lifting Condition

Transport Condition

In_place Condition


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Multiple analysis – code check results Different results at your finger-tips

- API WSD and default settings used in example below

Lifting Condition

Max Uf = 2.51

Transport Condition

Max Uf = 1.85

In_place Condition

Max Uf = 4.58


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Multiple analysis Frigg TCP2 MSF removal

Transportation

Lifting Condition

MSF: Main Support Frame


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How can Sesam help you –What is unique about us?


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Our value proposition and uniqueness An integrated and scalable life cycle solution for optimizing fixed and floating

structure design, modification and operation

Accumulates 50 years of software experience from the maritime and offshore industry

Commercial benefits- One vendor delivering a complete software suite for engineering design of ship and offshore

structures- Proven track record on work done on structures- Global presence with local sales, support and training- Scales with your business - Flexible licensing model- SW revenues used for further development – there are no share dividends to stock owners


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Our value proposition and uniqueness Closing the design loop by modern concept modelling and work process tools

- Quick modelling- Local model in global model- Scripting/parametric models- Changes during design- One model – many analyses- Interaction with hydro- Advanced hydrodynamics- Beam/plate code checking- Beam/plate fatigue- Non-linear pushover- Reporting

Presenter

Presentation Notes

Our uniqueness can be summarized as Efficient design iterations by combining modern concept modelling tools with workflow process tools. For fixed structures we support what other tools have, but we are particularly strong on Quick modelling Changes during design Beam code checking Non-linear pushover Reporting Similarly, for floaters where we are market leaders we are better in Quick modelling Interaction with hydro Advanced hydrodynamics Plate code checking Stochastic fatigue


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What’s needed to do topsides? Full blown version of GeniE

- Including waves, current, wind and soil- For floating structures – HydroD is needed

GeniE.lite- Limited by model size

- 500 beams or 10.000 finite elements- No plate code checking, waves, current, wind

and soil


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“Keppel is very pleased to participate and being consulted in the development of the redesign feature

to be launched in GeniE.”Gao Ming, Keppel Offshore and Marine


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Safeguarding life, property and the environment

www.dnv.com

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Sesam - Efficient Engineering of Topside Structures