a1 genie crane pedestal

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Sesam Crane pedestal

DNV Software – GeniE Crane Pedestal WorkshopRevised by Magnus NekstadRevised 28 July 2008

Modelling in GeniE

Sesam User Course in Curved Structure ModellingGenie Workshop:

Local model of crane pedestal

• The purpose of this workshop is to create a model intended for stress analysis of a crane pedestal installed on a floating vessel.

• The focus is primarily on making the structure and not the loads nor detailed mesh control. There are 2 loadcases covering selfweight and the mass of the lifting object. In addition there is a load combination accounting for dynamic amplification factor of the crane load.

• It is assumed that the user is familiar with structure modelling (beams and plates using snap to point modelling techniques). Furthermore, it is required that the user has basic knowledge on GeniE’s user interface and how the user may interact with the model to derive necessaryinformation (such as length, positions, properties, display settings and so on).

� Some detailed guidance is given in the beginning of the tutorial to exemplify how to work with GeniE

• The workshop is also accompanied with input files for GeniE (Journal file)

� You need to make mesh and run analysis to see results

• This workshop should be viewed on-line or on colour print out to best see the property colour coding.

� All pictures have been created using “paper background”

� Default viewing settings have been modified

• The structural data as well as the loads are fictitious

• This tutorial has been made with GeniE version V4.0-14 (5 June 2008) – it may be that you need this or a later version to complete this workshop

Part 0 - General

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Modelling in GeniE

• Part 0 – General introduction to the workshopPages 1-3

• Part 1 – Design premiseDefine the units, material and section typesPages 4-10

• Part 2 – Guiding geometryDefine the guiding geometry needed to define the outer hull and deck levelsPages 11-13

• Part 3 – Make the outer hullModel the hull interactively. You will se the symbols to the right that represent start and stop of beams during modelling. Notice that the symbol for right mouse bottom click is different from left mouse bottom clickPages 14 - 18

• Part 4 – Make the deck platesCreate the deck levels and insert stiffening in between using both plates and beamsPages 19 – 27

• Part 5 – Make the columnInsert the column between lower deck and above upper deck level Pages 28 – 32

• Part 6 – Create the web framesInsert three simple web frames and connect to the Pages 33 – 34

• Part 7 – Column stiffeningInsert vertical stiffeners as well as a ring stiffener at top of column Pages 35 – 38

• Part 8 – The craneModel the crane using beams in order to apply the loads at end of crane tip Pages 39 – 43

• Part 9 – Boundary conditionsInsert pinned boundary conditions along all free edges and ensure that the simplified crane beam is connected properly to the shell column model by using linear dependencies Pages 44 – 45

• Part 10 – LoadsCreate one loadcase with selfweight, another with 75 tonnes load at the crane tip and a load combination where loadfactor 1.6 is used on the crane load Pages 46 – 48

Part 0 - General

Click start of beam

1

Click end of beam

2

Use right mouse button to activate the context sensitive menu

3

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Modelling in GeniE

• Part 11 – Verify modelVerify the model before launching the analysis,Page 49

• Part 12 – Run analysisRun the analysis and see how the mesh and results changes when performing changes in the global mesh settings.Learn how to work with sets in results presentation and open the results in XtractPages 50 -57

Part 0 - General

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Modelling in GeniE

• Define units meters and N

� Start the program and open a new workspace File|NewWorkspace. Specify name Crane_pedestal_tutorial and use the default values for database units. Click OK when done.

» Notice, if you want Finite Element results in other units than N and m, you need to change now.

• Define materials

� Use the command Edit|Properties and select Material. Select Create/Edit Material to give the details for MAT1 (remember to tick “Allow edit”). Set the material type to default and click OK when done

Part 1 – Design premise

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Modelling in GeniE

• Define section properties

� Section profiles Tbar425x120x12x25, Tbar575x150x12x25 and Tbar885x200x14x35 are found from section libraries

� Section profiles (user defined name) Column, Crane_inner, Crane_outer and Hydraulic_cylinder are defined by the user

� Use the command Edit|Properties and select Section. Select Create/Edit section to start defining the sections. Select “Section Library”

� Find the right section library from “Browse” and select the library ‘tbar’ (a library containing typical Tbar ship profiles)


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Modelling in GeniE

� You may find the profiles Tbar425x120x12x25, Tbar575x150x12x25 and Tbar885x200x14x35

� The sections are now selected by clicking on Tbar425x120x12x25 and then RMB+click on Tbar575x150x12x25 and Tbar885x200x14x35

» The picture below shows the selection of Tbar425x120x12x25 and Tbar575x150x12x25

� Click OK and the profiles are now part of the design premise

� Click create/edit sectionto define the remaining profiles


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Modelling in GeniE

� Define the profiles Column, Crane_inner, Crane_outer and Hydraulic_cylinder as shown below. You may use mixed units as shown


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Modelling in GeniE

• Define the plate thicknesses Pl12, Pl15 and Pl30 as follows:

� Use the command Edit|Propertiesand select Thickness. Select Create/Edit Thickness to start defining the thickness properties


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Modelling in GeniE

• The thickness and section properties may now be accessed from the browser. Since the modelling will start with the outer hull, the plate thickness Pl15 should be set as default. Similarly, the first use of stiffeners will be at a deck level; you should set Tbar885x200x14x35 to defaults. Notice also the default symbol that will appear.

� Material default has already been set when creating the property



1


1

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Modelling in GeniE

• Specify the mesh settings for automatic mesh creation as follows:

� Edit|Mesh Rules


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Modelling in GeniE

• Insert a guiding plane from the command Insert|Guiding Geometry|Guide Plane Dialog and enter the values as shown.

� Give z-value 0 m, number of spacings 10 in each direction (equal length of all spacings)

» This plane is used as reference when making horizontal deck levels

� Using the view settings “Default display” you see the guide plane

Part 2 – Guiding geometry

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Modelling in GeniE

� Make a new guideplane to be used when creating the outer hull and other parts extending in vertical direction

» Enter the values as shown.


Type in your own values

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Modelling in GeniE

� Select GuidePlane 2 and copy to the other side of GuidePlane1.


Select guideplane

1


2

Select copy

3

Click startof copy vector

4

Click endof copy vector

5

Perform copyoperation

6

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Modelling in GeniE

• Insert two guidelines as follows:

� Insert|Guiding Geometry|Guide Line Dialog

� Before accepting above dialog,change z-coordinate for end point to 0.5 m

Part 3 – Make the outer hull

Start line

1

Find start point

2

End line

3

Find end point

4

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Modelling in GeniE

� Use the same technique to insert Curve2:

» Edit the lowest point and change z-coordinate from 2m to 2.5 m

� Insert|Guiding Geometry|Guide Line Dialog


Find start point

1

Find end point

2

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Modelling in GeniE

• Join Curve1 and Curve2 by using the fillet curve option

� The radius of the fillet curve shall be 2.5 m

� The steps are as follows:

» 1. Activate fillet curve

» 2. Click on Curve1 – it will change colour

» 3. Click on Curve2 – the minimum radius is calculated (2.278m)

» 4. Change radius to 2.5 by typing 2.5 and click <Enter>

» 5. The two curves (1&2) are now joined to a composite guide curve, Curve3


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Modelling in GeniE

• Copy Curve3 to the other end of the bottom guideplane as follows:

� 1. Select Curve3

� 2. Right click to activate the menu copy


Find start point

3

Find end point

4

Performcopy

5

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Modelling in GeniE

• Create the hull plate by a skin curve operation

� The steps are:

» 1. Activate skin curves

» 2. Click on Curve 3

» 3. Click on Curve4

» 4. Click on Curve 4 again to stop skinning operation and the hull plate is created having thickness 15mm since this was the default setting

• In case you had several curves click on each one sequentially and double-click on final curve


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Modelling in GeniE

• Create the horizontal deck levels at elevations2m, 5m, 7m, 11m, 14m and 15m. The stepsare:

� 1. Change default thickness value toPl12. Right click Pl12 in the Thicknessbrowser and select Set Default

� 2. Insert the top plate by clicking thefour plate corners as shown below. Usecommand Insert|Plate|Flat Plate Dialogor

Part 4 – Make the deck plates

First corner

1

Second corner

2

Third corner

3

Fourth corner

4

Above using ”Default display”

Right using ”Modelling – Structure”

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Modelling in GeniE

� 3. Copy Plate2 downwards to the other levels, also for elevation 2m. Find the copy vector from the model.

» Select the plate and RMB

» Click Copy Translate

» Click from position

» Click to position

» Picture to right shows copy toelevation 11m

» Use same copy technique and create plates at elevations 7m, 5m and 2m

» Notice for 2 meters use the same plate even though it is outside the hull. The plate will be trimmed in the next operation



2

From

3

To

4

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Modelling in GeniE

� 4. Trim Plate Pl7 so that it matches the hull form.

» Select the plate, RMB and select Divide

» The plate is now divided in two parts – the split is along the intersection with the hull. Select the outer part of the horizontal elevation and delete it.


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Modelling in GeniE

� 5. Make the stiffening between plates at elevation 14m and 15m

» Copy GuidePlane1 to elevations 14m and 15m

» Insert a vertical plate using the highlighted positions as the four plate corner points

» Select the new plate, RMB and click Copy Translate

» Specify copy vector 1.4 m in x-direction and copy 3 times


5 spacings

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Modelling in GeniE

» Repeat copy operation, but use vector (-1.4m, 0m, 0m)

» Select all the new vertical stiffening plates, RMB and click Copy Rotate

• Rotate around position (5m, 5m, 15m) which is the centre of the plate (and also centre of the column to be modelled)


Structural parts hidden for better visibility

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Modelling in GeniE

� 6. Make the vertical plates between lowest deck level and the hull. The steps are:

» Copy GuidePlane1 to deck elevation 2m

» Insert vertical plates at same positions as for the upper deck. Use same modelling procedure by inserting one plate and copy in positive and negative x-direction. Select all plates and rotate as on previous page

» Select all new vertical plates, RMB and click Divide

» Delete all plate parts outside the hull.


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Modelling in GeniE

� 7. For the remaining deck levels insert vertical stiffening using beams. Follow the steps:

» Set section property Tbar885x200x14x35 to default

» The stiffeners shall be inserted at the same locations as the vertical stiffener plates (see previous pages).

» Copy GuidePlane1 to elevation 11 m and use as reference.

» Insert one stiffener at elevation 11m (Insert|Beam|Straight Beam)

» Flush the stiffener to the plate elevation


From

1

To

2

RMB3

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Modelling in GeniE

» Select the stiffener and copy in positive and negative x-direction as follows

» Select all stiffeners, RMB and click Copy Rotate

• Rotate around position (5m, 5m, 11m)


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Modelling in GeniE

» Select all stiffeners and copy to the deck elevations below:


From

1

To

2

From

1

To

2

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Modelling in GeniE

• The steps are as follows

� 1. Select the top guideplane (GuidePlane5) and hide all other structure or guiding geometries. Right click the guideplane, click Visible Model and select Show selection only (or use ALT+S)

� 2. Look at the guideplane from top – rotate the guideplane or use tool button “View from Z” or (F8)

� 3. Make a curved guideline forming one quarter of the column circle

» Insert points for the curve first (Insert|Guiding Geometry|Guide Point Dialog)

» Use points to create the guide

Part 5 – Make the column

Origin

1

To

3

From

2

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Modelling in GeniE

� 4. Copy the guide curve to elevations 5m and 20m

» I.e. copy vectors (0,0,-10) and (0,0,5)

� 5. Copy and rotate the selected guidecurves-90 degrees

� 6. Select the guide curve highlighted above and move to the deck level below at elevation 2m, i.e. a copy vector (0,0-3)

� 7. Set default plate thickness to Pl30


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Modelling in GeniE

� 8. Make the column plates by a skin operation between the relevant curves. Remember to double click the end curve to finalise the skin command

» Make two quart parts and copy mirror these


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Modelling in GeniE

» Perform the Copy Mirror to complete the column

• You may also do a Copy Rotate using a rotation vector 180 degrees

� 9. Insert a vertical plate between deck levels 2m and 5m below the column

» Delete the highlighted beam

» Set plate thickness Pl12 to default

» Insert the plate


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Modelling in GeniE

� 10. Verify the plate thicknesses by using colour

» Remember to deactivate the Paintbrush tool button by clicking on it to get back to normal modelling view.


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Modelling in GeniE

• This part shows how to create three web frames. The procedure is as follows:

� 1. View the model from one side and make sure you see the vertical guideplane. Select the guideplane and show this only

� 2. Insert the web frame by using insert flat plate and snap point loop. Click the plate corners on the guideplane as shown, remember to close the loop by finally clicking on the start point again.

� 3. Select the web frame, RMB and divide it.Trim the plate to the hull by deleting thepart outside the hull

Part 6 – Create web frames

1st corner

1

2nd corner

2

3rd corner

3

4

5

6

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Modelling in GeniE

� 4. Join the plate parts of the web frame. Select all of them, RMB and click Join

� 5. Move and copy the web frame to final positions

» Move to intersect with first occurrence of stiffener

• Vector (0.8,0,0)

» Copy to mid position and other side of column as shown

• Notice: Structure hidden for better visibility

• Copy vectors (4.2,0,0) and(8.4,0,0) used

Part 6 – Create web frames

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Modelling in GeniE

• Specify vertical stiffeners and a ring stiffener at top of the column. Follow the steps:

� 1. Select the following structure and hide rest of structure

� 2. Set Section property Tbar425x120x12x25 to default

� 3. Zoom in to the bottom part of the column

� 4. Insert stiffeners by using command Insert|Beam|Straight Beam Dialog. Click on bottom point and edit the upper point so that the z—coordinate becomes 5m+15m (or 20m)

» Select the beam, RMB, Edit Beam and offset the beam

Part 7 – Column stiffening

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Modelling in GeniE

� 5. Repeat the same procedure so that the stiffeners are orientated as shown:

» Notice that you need to rotate the stiffener to the right to align correctly before making the offset (select beam, RMB, Edit Beam and choose rotate around local x-axis)

� 6. Select all the 4 stiffeners and rotate 3 times using 90 degrees

» Rotate around column centre line


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Modelling in GeniE

� 7. Insert the top ring stiffener by using Insert Beam|Curved Beam

» Set section property Tbar575x150x12x25 to default

» Insert the beam by clicking the start point and double click the end point

» Select the beam, RMB and align beam local axis to column plate

» Flip the beam so that flange is on inside


1

3

2

Click on column plate

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» Flush the stiffener to the inside of the column plate

» Copy rotate the stiffener 3 times using 90 degrees

• Column centre line as rotation axis


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Modelling in GeniE

• The crane is represented with beams to ease the load application. I.e. the load of the lifted object is applied at the crane tip instead of applying a load with force and moments (as a result of crane arm x force). To ensure that plane sections remain plane linear dependencies are inserted between bottom of crane beam and top of column plates. Follow the procedure outlined below:

� 1. Set section property “Column” to default

� 2. Create a start point of the crane beam by inserting guide linesat top of column

� 3. Insert the crane beam by Insert|Beam|Straight Beam Dialog. Find the start point by clicking on the reference point defined by the two guide lines above. Edit the end point as shown below (z-elevation 33m)

» Notice that the cranebeam is modelled as a beamand not a plate

Part 8 – The crane

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Modelling in GeniE

� 4. Select the beam, RMB and divide the beam at 7 meters from start position

» Use parameter 7/13 to divide

» Select the upper beam and divide using parameter 4/6


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Modelling in GeniE

� 5. Create the crane cantilever

» Set section property Crane_inner to default

» Use command Insert|Beam|Straight Beam Dialog to create the beam.

• Start point is at elevation +27 m

• End point is edited as shown below

» Double click the horizontal beam and make segments as follows:


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Modelling in GeniE

» Select the segment to the left and change section property to Crane_outer

• RMB to activate thecommands

• Double click in graphic window to exit segmented modelling view

» Move the segmented beam upwards 4 meters. Select the beam, RMB and Move


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Modelling in GeniE

» Select the segmented beam and move the end 2 m upwards

• RMB, Edit Beam and Move end

� 6.Insert the hydraulic cylinder

» Set section property Hydraulic_cylinder to default

» Insert the beam by clicking between points P1 and P2 as shown above


P1

1P2

2

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Modelling in GeniE

• The boundary conditions along plate members are assumed to be /fixed, fixed, fixed, free, free, free)

� Ensure there are guide lines along all relevant edges

� Select the edges and click “Create Support Curve”

» You may also insert support curves by using Remember to double click the end point

� Select the Support Curves, RMB, Properties and change from fixed in all dof’s to (fix, fix, fix, free, free, free)

Part 9 – Boundary conditions

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Modelling in GeniE

• Connect the top of the shell column to the lower part of the beam column and ensure plane sections remain plane

� Use a support rigid link

� Step 1: Select the independent point

» The bottom point of the crane beam

� Step 2: Decide boundary conditions for independent point

» Free in all degrees of freedom, i.e. free to move and rotate

� Step 3: Decide dependent region

» Centre of volume is in the middle of the column (i.e. same as the independent point)

» Ensure that all edges of the shell circle is part of region, use dx=6m, dy=6m, dz=0.2m)

� The symbols for the rigid support link looks like:

Part 9 – Boundary conditions

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Modelling in GeniEPart 10 – Loads

• Before making the loadcases make an analysis activity

� Right click in right browser pane area to accessthe commands

� Specify activity name Linear_static

• Make two loadcases to represent the structure selfweightand the crane load

� Create the loadcases from the browser pane area as shown

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• Include selfweight in LC1_stru

� Select the laodcase, RMB and choose Properties. Tick for ”Include structure self-weight in structural analysis”

• Ensure that LC2_cran is the active loadcase by selectingthe loadcase, RMB and choose SetCurrent

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• Include a point load at the crane tip equalto 75 tonnes x gravity≈ 750.000 N

� Insert|Explicit Load|Point Load

• Make a loadcombination LC3_comb and use load factor 1.6 on LC2_cran

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Modelling in GeniEPart 11 – Verify model

• Run Tools | Structure | Verify to verify the model before launching the analysis.

� The model verification should indicate that there are two disjoint model parts, but this is due to the program not treating the rigid support link as geometry. The analysis will run.

� If no other warnings or problems are reported, you can continue to the next page to run the analysis.

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Modelling in GeniEPart 12 – Run analysis

• Run the analysis from Tools|Analysis|Activity Monitor (or by using the shortcut ALT+D)

� There are several ways of verifying analysis details. The example below shows how to open the listing file from the analysis done by Sestra

• You may now look at the finite element mesh and results by selecting e.g. the view setting “Results with mesh”

� It is not the objective of this tutorial to do results presentation, but the results are accessed as follows or from using short-cut ALT+P (in this case the displacements are shown for the whole structure using load combination LC_comb)

� The mesh is also very coarse since nomesh details have been specified

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• Specify mesh setting of maximum 1 meter

� Create the mesh density Md_def from the Property Mesh browser and set to default.

• Re-run analysis by clicking ALT+D and investigate the new mesh and results

� In this case the VonMises stresses are shown

� The mesh is shown with a shrink factor of 0.9

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• Refine mesh setting to maximum 0.75

� Change Md_def from the Property Mesh browser

� Notice this change is not part of the attached input journal file

• Re-run analysis by clicking ALT+D and investigate the new mesh and results

� In this case the VonMises stresses are shown

� The mesh is shown with a shrink factor of 0.9

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• Make named sets and use these when presenting the results.

� Select structure, RMB and select Named Sets -> Give a name. If you want to use the sets when viewing results in other programs than GeniE the names should be max. 8 characters.

� You may also insert structure to existing sets

• Create the following named sets as follows:

� Acc_deck

� Complete

» Select all structure and create names set <Complete>

� Hull

» Select the outer hull and create <Hull>

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� One_deck

» Select members as shown and define <One_deck>

� Sec_deck

» Select members as shown and define <Sec_deck>

� Thi_deck

» Select members as shown and define <Thi_deck>

� Web_fram

» Select members as shown and define <Web_fram>

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� Pedestal

» Select members as shown and define <Pedestal>

• Remember to include internal stiffeners

� Tank_pla

» Select members as shown and define <Tank_pla>

• All sets are available from the Sets browser pane. You may show one (or several) at a time by selecting one, RMB and choose Visible Model|Showselection only (or use ALT+S)

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• Run analysis again by ALT+D – you may now look at results for this set only.

� Use same procedure for selecting other sets.

• Go to a view where you can select plates, click the top deck plate and use short command ALT+Minus to hide the plate. Go to the Results with mesh view and click exclamation mark (refreshing the graphics). You now see the results for the interior parts and bottom plate only

� Named set Pedestal also shown

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• Open the results database (R1.SIN) in Xtract to get access to general FE results processing

� You find the file where you have stored your GeniE model and results

» See picture below

� You have access to the sets in Xtract as well.

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a1 genie crane pedestal

Documents

crane load pages

local model of crane

end of crane tip pages

column pages

simplified crane beam

structure modelling

upper deck level pages

lower deck