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. 2

Common challenges in design

SesamTM
25 March 2011

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

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”

SesamTM
25 March 2011

How can Sesam help you –
Making a model in GeniE

Structure

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25 March 2011

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

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25 March 2011

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

SesamTM
25 March 2011

GeniE uniqueness - combined beam/shell models
 Faster modelling  Faster and easier re-analysis and
- Stiffeners selected from libraries optimization
- No need for calculation and evaluation of - Easy change of beam profiles from libraries
effective flange - Plate thickness changed without changing
- No lumping of loads properties for all stiffeners
- No doubts – model structure as is - Easy to change geometry, stiffener arrangement
- Always a consistent topology and other properties
- Easy to add new stiffeners or other details
 More accurate results (brackets, holes etc.)
- No simplified assumptions on effective flange
and lumping of loads
- Better visual verification of model and results

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 Parametric modelling – define variables in script files

4.23E07 5.E07

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 Same system – offshore and maritime
- Fixed structures, semi’s, FPSO’s, Spar, TLP
- Tankers, containership, bulk, +++

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25 March 2011

 Combine detailed models in
a global model
Beam

Plates

FE beam

FE shell

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

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25 March 2011

Making a model in GeniE

Loads

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25 March 2011

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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25 March 2011

GeniE uniqueness – load application
 Easy to define compartment loads
- Content and filling degree is enough

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25 March 2011

GeniE uniqueness – load application
 Acceleration loads – multiple choices
- Constant and varying acceleration – different accelerations on various parts of structure

Lower level loads from mass Upper level loads from Rotational acceleration
x acceleration (x & z-dir) mass x acceleration (z-dir) Harmonic induced wave
motion
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25 March 2011

Topsides/modules on jackets or floaters
 Topside on Jackets  Topside on Floaters
- All is done inside GeniE - Opt. 1 - Integrated: Results from HydroD
- Focus of this presentation (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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25 March 2011

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

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25 March 2011

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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25 March 2011

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 Centripetal
Acceleration
 Sp4: 2mm
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25 March 2011

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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25 March 2011

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

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25 March 2011

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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25 March 2011

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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25 March 2011

 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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 Consistency between beam and shell elements

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25 March 2011

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

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25 March 2011

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….

SesamTM
25 March 2011

Demo case – add details
 Add brackets

SesamTM
25 March 2011

First assessment in GeniE

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25 March 2011

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

SesamTM
25 March 2011

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

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25 March 2011

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)

SesamTM
25 March 2011

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

With cubic deflection

Linear deflection ≈ deformation view
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25 March 2011

Beam deflections – 2D view
 Dy, Dz and Defl = sqrt(Dy^2 + Dz^2)
 Per load-case(s)
 Envelopes
 Worst condition
 Relative deflections

SesamTM
25 March 2011

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)

SesamTM
25 March 2011

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

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25 March 2011

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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25 March 2011

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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25 March 2011

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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25 March 2011

Document code check results
 Graphically – complete model

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25 March 2011

Document code check results
 Graphically – parts of structure only

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25 March 2011

Report code check results
Loadcases Utilisation factor
 Print out using filters - All - All
- Worst - Above
- User defined - Below

Positions Members
- All - All
- Worst - Current selection

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25 March 2011

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

SesamTM
25 March 2011

Redesign – single members
 Select a capacity member for redesign
 Modify parameters
- Preliminary results automatically computed

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25 March 2011

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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25 March 2011

Redesign – multiple members
 Select capacity members for redesign
 Modify parameters
- Preliminary results automatically computed

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25 March 2011

Redesign – segmented beams
 Single or multiple

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25 March 2011

Redesign – segmented beams
 Before and after

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25 March 2011

Plate code checking in GeniE

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25 March 2011

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

Max Area Moment

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25 March 2011

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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25 March 2011

Code checking of stiffened panels - offshore
 Yield check of plates – based on membrane stress
- Includes a safety factor S

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25 March 2011


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25 March 2011

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

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25 March 2011

Multiple analysis in GeniE

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25 March 2011

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

Lifting Condition Transport Condition In_place Condition

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25 March 2011

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

Lifting Condition

Transport Condition

In_place Condition
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25 March 2011

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
SesamTM
25 March 2011

Multiple analysis
 Frigg TCP2 MSF removal

Transportation

MSF: Main Support Frame

Lifting Condition

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25 March 2011

What is unique about us?

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25 March 2011

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

SesamTM
25 March 2011

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

SesamTM
25 March 2011

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

SesamTM
25 March 2011

“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

SesamTM
25 March 2011

Safeguarding life, property
and the environment

www.dnv.com

SesamTM
25 March 2011

Sesam - Efficient Engineering of Topside Structures

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