Sesam - Efficient Engineering of Topside Structures

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SesamTM 40 years of success Efficient engineering of topside structures Pål Dahlberg, Sesam Principal Sales Executive, DNV Software 10 May 2011

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 -

SesamTM 25 March 2011 © Det Norske Veritas AS. All rights reserved.

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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? SesamTM 25 March 2011 © Det Norske Veritas AS. All rights reserved.

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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

 Faster and easier re-analysis and optimization

- 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

- 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.)

 More accurate results - No simplified assumptions on effective flange and lumping of loads - Better visual verification of model and results


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

4.23E07

5.E07


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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

Beam

Plates

FE beam

FE shell


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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)


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Rotational acceleration Harmonic induced wave motion

Topsides/modules on jackets or floaters  Topside on Jackets

 Topside on Floaters

- All is done inside GeniE

- 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

- Focus of this presentation


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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

Centripetal Acceleration


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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….


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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 redesign


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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 SesamTM 25 March 2011 © Det Norske Veritas AS. All rights reserved.

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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? SesamTM 25 March 2011 © Det Norske Veritas AS. All rights reserved.

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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


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Loadcases - All - Worst - User defined

Utilisation factor - All - Above - Below

Positions - All - Worst

Members - All - Current selection

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 nonrectangular 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 SesamTM 25 March 2011 © Det Norske Veritas AS. All rights reserved.

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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 The “master” model

 Multiple analysis in same project - E.g. Lifting, transport, in-place - Varying parameters - Structure - Boundary conditions - Load cases

Lifting Condition

Transport Condition


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In_place Condition

Multiple analysis – graphic results  Different results at your finger-tips - Bending moments shown

Lifting Condition Transport Condition

In_place Condition SesamTM 25 March 2011 © Det Norske Veritas AS. All rights reserved.

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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

Transport Condition

In_place Condition

Max Uf = 2.51

Max Uf = 1.85

Max Uf = 4.58


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Multiple analysis  Frigg TCP2 MSF removal

Transportation

MSF: Main Support Frame

Lifting Condition


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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


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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

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