Sesam - A Complete System for Strength Assessments of Fixed Structures
Upcoming SlideShare
Loading in...5
×
 

Sesam - A Complete System for Strength Assessments of Fixed Structures

on

  • 1,159 views

Seminar "Efficient Design of Topside Structures" (Rio, April 2012) by Pal Dahlberg

Seminar "Efficient Design of Topside Structures" (Rio, April 2012) by Pal Dahlberg

Statistics

Views

Total Views
1,159
Slideshare-icon Views on SlideShare
1,152
Embed Views
7

Actions

Likes
0
Downloads
61
Comments
0

3 Embeds 7

http://storify.com 3
http://www.linkedin.com 2
https://www.linkedin.com 2

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Sesam - A Complete System for Strength Assessments of Fixed Structures Sesam - A Complete System for Strength Assessments of Fixed Structures Presentation Transcript

    • SesamTM40 years of successA complete system for strength assessments of fixed structuresPål Dahlberg, Principal Sales Executive, DNV SoftwareApril 2012
    • Efficient engineering of fixed 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 - Fatigue - Launching and upending  Fixed structures - Jackets, Jack-Ups, Bridges, Flare- booms….1 May 2011© Det Norske Veritas AS. All rights reserved. 2
    • Common challenges in design1 May 2011© Det Norske Veritas AS. All rights reserved. 3
    • The importance of the Sesam design loop 40-60% of engineering time often spent in evaluation How fast can you do it over again?1 May 2011© Det Norske Veritas AS. All rights reserved. 4
    • 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”1 May 2011© Det Norske Veritas AS. All rights reserved. 5
    • How can Sesam help you – Making a model in GeniE Structure1 May 2011© Det Norske Veritas AS. All rights reserved. 6
    • Overall capabilities for fixed structures  From modelling to stochastic fatigue - Linear structural analysis of unlimited size - Hydrodynamic and pile/soil analysis - Code check of beams and joints - Fatigue and earthquake analysis - Gust wind fatigue included - Non-linear analysis (push-over) - Launching & upending analysis1 May 2011© Det Norske Veritas AS. All rights reserved. 7
    • The Sesam Jacket Package  Packaged to meet your needs - Topside, equipments, flare booms, bridges... - Supporting structure (hydrodynamic and structural) - Pile/Soil (non-linear)  Based on Morison equation - Wave, current, wind - Deterministic or stochastic  Code checking, fatigue, result presentation, re-design, design reporting, push-over (non-linear), launching  GeniE is the main tool – supported by - Sestra, Wajac, Splice, Framework, Usfos, Installjac1 May 2011© Det Norske Veritas AS. All rights reserved. 8
    • The SESAM suite of programsPackages:DeepC Coupled globalresponse of moored deep water floating systemsGeniE Design of beam and plate offshorestructuresHydroD Hydrodynamicanalysisof ship and floatingoffshore structures1 May 2011© Det Norske Veritas AS. All rights reserved. 9
    • Application domains of GeniE  Jackets1 May 2011© Det Norske Veritas AS. All rights reserved. 10
    • Application domains of GeniE1 May 2011© Det Norske Veritas AS. All rights reserved. 11
    • The benefit of concept technology  Dynamic adjustment of can, stub, cone and gap when modifying chord or brace properties seen from above1 May 2011© Det Norske Veritas AS. All rights reserved. 12
    • GeniE uniqueness – structure modelling  Parametric modelling – define variables in script files 4.27E07 3.58E071 May 2011© Det Norske Veritas AS. All rights reserved. 13
    • Demo-time Make a local shell joint in a jacket model1 May 2011© Det Norske Veritas AS. All rights reserved. 14
    • Demo case – The base model  Structure (jacket beams only), piles, soil, environment1 May 2011© Det Norske Veritas AS. All rights reserved. 15
    • Demo case – The base model  Some typical results viewed in the plug-in component GLview Plugin not installed. Press here to install plugin1 May 2011© Det Norske Veritas AS. All rights reserved. 16
    • Demo case – The base model  The selected joint will be converted to a shell model - Beam model: Max deformation is 0.825 mm1 May 2011© Det Norske Veritas AS. All rights reserved. 17
    • Demo case – The base model  Max axial stresses 480 kpa at 0 m 469 kpa at 1 m1 May 2011© Det Norske Veritas AS. All rights reserved. 18
    • Demo case – Convert beams in joint to shells  Mesh density of shell 0.125 meter1 May 2011© Det Norske Veritas AS. All rights reserved. 19
    • Demo case – Convert beams in joint to shells  Deformations correspond to pure beam model1 May 2011© Det Norske Veritas AS. All rights reserved. 20
    • Demo case – Convert beams in joint to shells  The stresses differ from pure beam model – as expected1 May 2011© Det Norske Veritas AS. All rights reserved. 21
    • Demo case – Convert beams in joint to shells  Some typical results viewed in the plug-in component GLview Plugin not installed. Press here to install plugin1 May 2011© Det Norske Veritas AS. All rights reserved. 22
    • 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? - 15 min? - 10 min?  You can start your stop watches now - …..and not using a predefined special purpose build script for this case….1 May 2011© Det Norske Veritas AS. All rights reserved. 23
    • How can Sesam help you – Making a model in GeniE Loads1 May 2011© Det Norske Veritas AS. All rights reserved. 24
    • The benefit of concept technology  Load or mass definitions from equipments - Automatic - Always in balance - Load patterns – footprints - Load patterns – primary or secondary beams  Traditional load or mass definitions - Point loads - Line loads - Pressure loads - Point mass - Temperature loads - Prescribed displacements1 May 2011© Det Norske Veritas AS. All rights reserved. 25
    • GeniE uniqueness – load application  Easy to apply loads to complex shapes1 May 2011© Det Norske Veritas AS. All rights reserved. 26
    • Hydrodynamic analysis slender structures  Hydrodynamic analysis of stationary vessels - Morison equation on beam model - Several wave theories (Airy, Stoke 5th, Dean stream function, Cnoidal and Newwave) including the current - Wind included in deterministic analysis or separately  Results - Deterministic load calculation in time domain - Calculation of force transfer in the frequency domain - Time domain simulation of loads for a given short term sea-state - Global responses including rigid body motions and sectional forces/moments - Pressure and accelerations - The loads are automatically used by subsequent structural analysis1 May 2011© Det Norske Veritas AS. All rights reserved. 27
    • Pile/soil analysis  Non-linear analysis  Soil modelling - Scour - Soil types sand and clay - P-Y, T-Z and Q-Z curves - Standards and user defined - Soil curves - Soil data - Soil sub-layers  Pile - Modelling - Characteristics - Seabed scour1 May 2011© Det Norske Veritas AS. All rights reserved. 29
    • How can Sesam help you – Making a model in GeniE Analysis1 May 2011© Det Norske Veritas AS. All rights reserved. 30
    • Structural analysis & design  Linear static and dynamic analysis - Unlimited in size using standard hardware for large problems  Stress and deflection assessments - Efficiently combine results, scan results and present results for large models with many loadcases  Code checking yields utilisation factors - Beams according to API/WSD & AISC, API/LRFD & AISC, Norsok & Eurocode, ISO and DS - Stiffened and un-stiffened plates according to API, DNV RP C201.1, NPD and PULS (DNV RP C201.2)  Fatigue life - Deterministic (real waves) and stochastic approach (unit waves with load transfer functions) for beams - Stochastic approach for plates - Gust wind fatigue for beams1 May 2011© Det Norske Veritas AS. All rights reserved. 31
    • Local analysis Characteristic t x t1 May 2011© Det Norske Veritas AS. All rights reserved. 32
    • How can Sesam help you – Result assessment Beam deflections and stresses1 May 2011© Det Norske Veritas AS. All rights reserved. 37
    • Beam stresses Single load case  2D graphs, scanning and envelopes - Print to report Envelope (max/min)1 May 2011© Det Norske Veritas AS. All rights reserved. 38
    • Beam deflections Single load case  2D graphs, scanning and envelopes - Print to report Envelope (max/min)1 May 2011© Det Norske Veritas AS. All rights reserved. 39
    • How can Sesam help you – Result assessment Code checking of beams and joints1 May 2011© Det Norske Veritas AS. All rights reserved. 40
    • Code checking jackets/jack-ups/topsides  Approach - Make capacity manager(s) - Define members and/or joints - Specify code of practice, loadcases and code check settings - Compute code checking forces - Run code check - Reporting – graphically or text based - Re-design of members - Re-run all to update mass and stiffness1 May 2011© Det Norske Veritas AS. All rights reserved. 41
    • Code checking jackets/jack-ups/topsides  Supporting beam and tubular joint code check standards - API WSD 2002 (incl. AISC 2005) - API WSD 2005 (incl. AISC 2005) - API LRFD 2003 (incl. AISC 2005) - NORSOK 2004 (incl. Eurocode 2005) - ISO 19902 2007 (incl. Eurocode 2005) - DS 412 / 4491 May 2011© Det Norske Veritas AS. All rights reserved. 42
    • Create & modify joint capacity members  Used in punching shear1 May 2011© Det Norske Veritas AS. All rights reserved. 43
    • Code checking jackets/jack-ups/topsides  Demo case - Topside member code checking - Jacket tubular punching shear check1 May 2011© Det Norske Veritas AS. All rights reserved. 44
    • How can Sesam help you – Result assessment Fatigue1 May 2011© Det Norske Veritas AS. All rights reserved. 45
    • Principles for fatigue - basics  Miner’s rule of cumulative damage gives a usage factor (interaction ratio)  Fatigue life = target fatigue life / usage factor  Framework fatigue analyses - Deterministic according to American Welding Society (AWS) - Many waves stepped through structure - Static (or dynamic) linear analysis - Stochastic (or spectral) according to Vugts & Kinra - Frequency domain wave load analysis - Quasi-static or dynamic frequency domain analysis - Rainflow counting (new in Sesam 2011 ) - Regular or irregular wave load time series fatigue  Which method to use? - Your decision1 May 2011© Det Norske Veritas AS. All rights reserved. 46
    • Principles for fatigue – SCF’s  3 SCFs for each hotspot local beam - Axial stress – SCFax coordinate system - In-plane bending stress – SCFby z x - Out-of-plane bending stress - SCFbz in-plane  Type of SCFs axial force - DEFINE FATIGUE-CONSTANTS … bending - Global SCFs where no other SCFs assigned - Minimum SCFs when parametric formulae used - ASSIGN SCF JOINT … - LOCAL / GLOBAL out-of-plane - PARAMETRIC: Efthymiou, Kuang, Wordsworth, Lloyds, Smedley & Fisher bending - ASSIGN SCF MEMBER … - LOCAL / GLOBAL - Parametric: BUTT-WELD / CONE-TRANSITION1 May 2011© Det Norske Veritas AS. All rights reserved. 48
    • Deterministic fatigue  Wajac - Several wave directions wave directions - Several waves (any theory) for each direction - Each wave stepped through structure (non-linear drag)  Sestra steps - Structural analysis waves: theory + height + length - Loads = directions  waves  steps - No other loads (*)  Framework stress H - Maximum stress difference for each wave gives stress range stress range: - Environmental data: S = max. diff. long term wave height distribution Hi determines number of cycles log N ni (*) Utility tool – DetSfile - converts “regular loads” to “wave loads”1 May 2011© Det Norske Veritas AS. All rights reserved. 50
    • Stochastic fatigue  Wajac - Several wave directions wave directions - Several frequencies (linear harmonic waves) for each direction - Linearization of drag 1  Sestra - Quasi-static or dynamic analysis - Loads = directions  wave frequencies waves: harmonic, unit height - Complex loads and complex results  Framework - Each wave direction given probability - Wave statistics defined and assigned to directions: - Create scatter diagram - long term distribution of wave heights vs. zero up-crossing - Assign wave spectrum to scatter diagram - Create wave spreading function and assign to scatter diagram1 May 2011© Det Norske Veritas AS. All rights reserved. 53
    • Stochastic fatigue  Unit waves, different frequencies / directions  Demands linearity wave height / wave force - Linear harmonic Airy wave 1 - Linearization of drag (FD = ρ (D/2) Cd vn |vn|) - Linearization of variable submergence: max! - Choose between two linearization methods: 1 - Equivalent linearization - Linearization with respect to wave height - No contribution from current to loads  Distributed loads (load transfer functions) transferred to structural analysis for all waves  Frequency domain  complex loads  Prepares for quasi-static or dynamic structural analysis (Sestra) and stochastic fatigue analysis (Framework)1 May 2011© Det Norske Veritas AS. All rights reserved. 55
    • Deterministic & Stochastic Fatigue Some pro’s and con’s  Deterministic - More accurate wave loads (any theory and proper drag), but many load cases - Together with piles and soil - Simple and straight forward - Often used to establish the general acceptability of fatigue resistance or screening to identify most critical details to be considered in stochastic approach  Stochastic - Structural dynamics and better coverage of environmental conditions - Prior to fatigue analysis partial damage may be set - More preparation of input needed – need to run eigenvalue analysis to determine quasi-static approach or not - Natural periods higher than 3 sec. -> use dynamic1 May 2011© Det Norske Veritas AS. All rights reserved. 58
    • How can Sesam help you – What is unique about us?1 May 2011© Det Norske Veritas AS. All rights reserved. 59
    • 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 - Reporting1 May 2011© Det Norske Veritas AS. All rights reserved. 61
    • “Keppel chose Sesam software for its user-friendliness and technical reliability as well as cost-effectiveness.” Paul Liang, Section Manager, Engineering Division Keppel O&M.1 May 2011© Det Norske Veritas AS. All rights reserved. 62
    • Safeguarding life, property and the environment www.dnv.com1 May 2011© Det Norske Veritas AS. All rights reserved. 63