SOFTWARE. Sesam user course. 29 February 2016 Postresp basic. Ungraded SAFER, SMARTER, GREENER DNV GL 2014

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1 SOFTWARE Sesam user course DNV GL 1 SAFER, SMARTER, GREENER

2 Wadam in Sesam Overview Sesam Manager Fatigue Manager MAIN TOOLS GeniE HydroD Sima DeepC conceptual modeller and code checking beams & plates environmental modeller, stability and hydrodynamics marine operations deep water mooring and riser analysis PREPROCESSING import NAPA, Sacs, ACIS, DFX, Nastran, Ansys Patran-Pre general FE modelling Presel superelement assembly STRUCTURAL HYDRODYNAMICS Wadam frequency domain wave loads Wajac wave loads on frame structures Sestra linear statics and dynamics Submod submodelling Splice structurepile-soil interaction Waveship sea-keeping analysis for ships Wasim time domain wave loads Sesam Interface File Usfos progressive collapse Installjac launching of jackets Simo time domain motions Mimosa mooring analysis Riflex non-linear slender structures POSTPROCESSING Postresp presentation of statistical response Framework frame fatigue and earthquake Profast probabilistic fatigue and inspection Xtract presentation & animation of results Stofat shell/plate fatigue Cutres presentation of sectional results CAESES simulation-driven design Pipeline Tools strength and fatigue of offshore pipelines Proban probabilistic, reliability and sensitivity 2

3 What you can do with Postresp Display response variables Combine response variables Display response spectra Short term statistics significant/expected values probability of exceedance from response level and vice versa extremes Long term statistics fatigue extremes workability 3

4 Or in other terms: Use Postresp to compute the practical consequences for the structure in given sea-states based on the more abstract frequency domain results produced by Wadam, Wasim, Waveship, Wajac, Sestra. Wadam/Wasim Seastate Transfer function Postresp Response The following terms all mean the same thing Response amplitude operators (RAO) Transfer functions Response variable 4

5 Starting Postresp from HydroD Select a Wadam run, Wasim activity or Fourier activity in the browser Click Start Postresp after right-clicking on the Wadam run or Wasim activity 5

6 Postresp User Interface The Postresp menu and message window 6

7 Postresp input G*.SIF/.SIN/.SIU file (WAMIT files Currently not available) User specified transfer functions Other direct user input 7

8 Reading data from file Done automatically when started from HydroD 8

9 Which response variables do I have? Similar overview can be obtained for all read or created quantities 9

10 Reference frame for motions and forces Motions and forces are referred to the motion reference point defined in the input The reference frame has its origin in the motion reference point and the xy-plane is parallel to the free surface This reference frame must be used when points are defined in Postresp 10

11 Sending plots to file or printer Directly to printer Plot file for reports 11

12 Sending print to file or printer 12

13 Designing the plot - axes 13

14 Designing the plot - title Changes to axes or title only take effect on the next plot that is displayed 14

15 DEFINE menu To compare results from more than one dataset, select All 15

16 PRINT menu 16

17 DISPLAY menu 17

18 Identification of sectional loads In HydroD the Postresp name of the sectional loads is displayed The sections are automatically sorted by increasing x (or y or z) 18

19 CREATE menu Necessary for all statistical computations Offbody points defined in Wadam/Wasim are transferred to Postresp 19

20 Combination of response variables Built-in combinations Displacement, velocity or acceleration in specified points (absolute value in any of the x, y or z-directions) Relative vertical motion (relative to incoming wave) CREATE RESPONSE-VARIABLE COMBINED-MOTION First and second derivatives CREATE RESPONSE-VARIABLE FIRST-DERIVATED CREATE RESPONSE-VARIABLE SECOND-DERIVATED General combinations Specified by user CREATE RESPONSE-VARIABLE GENERAL-COMBINATION 20

21 Combination of response variables Accelerations including g-component due to roll motion. To keep mass in place a force is required: F=m yacc+m g sin(phi)=m(yacc+g phi) yacc Z Z' -gsin(phi) Y' g Y phi 21

22 Combination of response variables Accelerations including g-component due to pitch motion. To keep mass in place a force is required: F=m xacc-m g sin(theta)=m(xacc-g theta) Z Z' theta xacc gsin(theta) g X' X 22

23 Short term statistics Step 1: Create a wave spectrum CREATE WAVE-SPECTRUM 23

24 Wave spectra Pierson-Moscowitz (parameters Hs, Tz) fully developed sea JONSWAP (parameters Hs, Tz, ) default is normally used for other parameters 1 < < 5, typical value 3.3 ( =1 gives PM-spectrum) Gamma (parameters Hs, Tz, l, n) Cannot be displayed or plotted l=5, n=4 gives PM-spectrum Double-peaked (Torsethaugen) (parameters Hs, Tp) Ochi-Hubble (combination of two Jonswap spectra) ISSC (parameters Hs, T1) User defined 24

25 Short term statistics Step 1: Create a wave spectrum CREATE WAVE-SPECTRUM Step 2: Create a wave spreading function CREATE WAVE-SPREADING 25

26 Wave spreading function 26

27 Short term statistics Step 1: Create a wave spectrum CREATE WAVE-SPECTRUM Step 2: Create a wave spreading function CREATE WAVE-SPREADING Step 3: Create response spectrum for a selected response variable CREATE RESPONSE-SPECTRUM 27

28 Heave RAO 28

29 Wave spectrum 29

30 Response spectrum 30

31 Response/wave spectrum statistics 31

32 Response/wave spectrum statistics n Spectral moments: M n S( ) d( ) 2 Variance: M 0 0 Standard deviation: Significant response: Hs 4 (Mean of largest 1/3, double amplitude) Mean zero up-crossing period: Tz 2 M 0 / M 2 Mean period: T1 2 M 0 / M1 Printed by Postresp: Hs, Tz, M 0, M1, M 2, M 4 32

33 Short term statistics Step 1: Create a wave spectrum CREATE WAVE-SPECTRUM Step 2: Create a wave spreading function CREATE WAVE-SPREADING Step 3: Create response spectrum for a selected response variable CREATE RESPONSE-SPECTRUM Step 4: Compute and print short term statistics PRINT SHORT-TERM-STATISTICS 33

34 Available short term statistics computations For a given response level Compute probability of exceedance For a given probability of exceedance Compute corresponding response level For a given duration of a sea state Compute most probable largest response Compute probability of exceedance No. of zero up-crossings For a given duration of a sea state and a given probability level Compute the response level for which the probability that the maximum response in a randomly selected time series with the given duration is larger than this value, has the specified value Compute probability that a single peak is larger than the computed response value 34

35 Short term statistics computations 35

36 Probability of exceedance two different things This is the probability that a single peak is larger than the computed value Here probability of exceedance means the probability that the maximum response in a time series with the given duration is larger than the computed value 36

37 Most probable largest response The computed most probable largest response for a given duration has a 63% probability of being exceeded It is a 63% chance that the highest peak in a selected realization will be larger than the predicted most probable largest response Max. response 37

38 Short term response Step 1: Create a sequence of wave spectra CREATE WAVE-SPECTRUM FULL-RANGE Step 2: Create short term response for a selected response variable CREATE SHORT-TERM-RESPONSE Step 3: Display or print short term response DISPLAY SHORT-TERM-RESPONSE PRINT SHORT-TERM-RESPONSE 38

39 Short term response as function of Tz First order quantities: Significant value per Mean drift: Expected value per 39

40 ULS-analysis of semi-submersible 40

41 Design wave selection 41

42 Responses for design wave selection Cut plane is at centreplane Moments are computed relative to a point in the waterline above COG Accelerations are computed at centre of deck 42

43 Environmental description 43

44 100 year contour example (DNV RP C205) DNV-WW scatter diagram Correction for steepness criteria Hs Scatter diagram Steepness criteria Tz 44

45 The world-leading provider of software for a safer, smarter and greener future DNV GL Software software.support@dnvgl.com SAFER, SMARTER, GREENER 45