Sesam for Collapse Analysis
-
Upload
joao-henrique-volpini-mattos -
Category
Technology
-
view
1.139 -
download
4
description
Transcript of Sesam for Collapse Analysis
Pål Dahlberg, Sesam Principal Sales Executive
1
17 April, 2012
SesamTM 40 years of success
Sesam for collapse analysis
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Benefits from using Sesam for jackets
2
Collapse analysis
Requalification
Extreme conditions,
accidents, fire, explosion
New builds covering
entire life cycle
MTO, deflection check,
code check, fatigue
Same model for all stages – can be shared with other units like the floating department
Manage existing
re-analysis models
Understand models over time,
produce and view results
Modification work
- all phases
Design of new parts
Re-design of existing
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
3
Non-linear analysis - Re-qualification - Accidents - Collapse & large scale deformations - Fire & explosions
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
4
Packages:
DeepC Coupled global
response
of moored deep water
floating systems
GeniE Design of beam and
plate offshore
structures
HydroD Hydrodynamic
analysis
of ship and floating
offshore structures
The SESAM suite of programs
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Our tools – your solutions – your decisions
5
Linear analysis (wave, pile/soil)
Deflections, Stresses,
Code-check, Fatigue, Earthquake
Transportation, lifting
Deflections, Stresses,
Code-check, Fatigue
xml
Transportation, launching
Deflections, Stresses,
Code-check, Fatigue
xml
Non-linear analysis,
collapse, accidents,
re-qualifications
fem
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
6
Structural analysis & design
Non-linear analysis - Accidents: Member yields and changes shape
- Impact, Collision, Explosion, Dropped objects
- Geometry changes significantly - Lifting operations, cable structures
- Loads depend on structural response - Wave, current, wind, motions
- Static analysis - Ultimate strength, Energy absorption
- Dynamic simulation (of real events) - Collision, explosion, motions
- Environment (wave, buoyancy, stability, wind)
- Foundation - Pile, soil, spudcan (jack-up)
- Temperature effects - Changed material properties, Fire
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
7
Non-linear analysis
USFOS is a specialized tool for ultimate resistance
evaluation of typical offshore structures
- Increased efficiency
- Better numerical predictions
- Lower threshold for new users to enter complex physics
The ultimate resistance of a structure is important
for many reasons
- New loading conditions, linear design exceeded, e.g.
- Extreme waves, increased explosion pressure
- Increased platform weight, extra conductors
- Damaged structure (cracks etc) – necessary to repair
immediately?
- Energy absorption performance
- Boat landing, crane operations/dropped objects, vessel
impact etc.
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
8
Non-linear analysis in Usfos
Why non-linear
- Linear codes cannot describe ductility
(metal)
- Linear codes cannot account for the
change in geometry for increasing
loads
- Usfos includes “all” physical effects and
predicts the “real” behaviour of a
structure
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Importing models into Usfos
9 9
GeniE Sacs
Model Wave loads Soil
Model consistency :
The Sacs input file The GeniE model The Usfos model
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Importing models to Usfos
Migration to Usfos
- Detailed model not needed for Collapse analysis
- This model would benefit from a “clean-up”
- Deck plating Coarse Mesh
- Necessary to get rid of the small gaps
- Beams One element per physical member
- Enough for detection of buckling & Plastic Hinges (end
nodes + middle of beam)
- Gravity + Explicit Deck Loads + Wave load (to be
exported to Usfos)
- More loads can easily be imported to Usfos, but they
should be relevant for collapse analysis
- Remove Dummy beams Not relevant for non-linear
analysis
- Wave loads exported from GeniE as explicit loads
- No need to define wave data and hydrodynamic
coefficients in Usfos
11
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Importing models to Usfos
How to do it?
- Start Usfos (Xact) and import the structure and wave load data
12
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Collapse analysis
History Plots
- Global Load vs. Displacement of Control Node (normally a node with large displacements)
- Global Stiffness vs. Step Numbers
13
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Collapse analysis
Displacements Plastic utilization
14
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Collapse analysis
Element forces
15
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Boat impact
Boat Impact
- Energy specified by user to be dissipated
- Local Denting of Tube
- Buckling & Plastic Hinges for local Hit Member
- Fracture Criteria based on strains
- In this case when less 0.15
- Global Deformation of the Global Model
16
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
Boat impact
History Plots (Global Load = 1, means
Max Impact Energy)
- Shown for control node
Plastic utilisation
17
© Det Norske Veritas AS. All rights reserved.
SesamTM
13 December 2011
18
Safeguarding life, property
and the environment
www.dnv.com