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GTSTRUDL

Modeling Base PlateAttachments with Partial Welds

Rob AbernathyCASE CenterGTSUGJune, 2012 Seattle, WA

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GTSTRUDL

What is a Partially Welded Attachment?

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Attachments are assumed to be welded to the baseplate along all attachment lines. However, in some

situations, only part of the attachment is welded to thebase plate. In versions 31 and earlier of the BasePlate Wizard, this situation could only be modeled bycreating a custom attachment which included thewelded parts of the attachment and omitted the

unwelded parts. Version 32 adds new tools to allowmodeling the unwelded parts of attachments.

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GTSTRUDL

Custom Attachment Omitting Unwelded Lines

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A wide flange welded on the flanges but not the web couldbe modeled as 2 lines, leaving out the line representingthe web. You would need to create the two line versionsince the standard profiles are assumed to be welded allaround.

StandardW8x10

CustomW8x10 -Flanges

only

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GTSTRUDL

Custom Attachment .gtbp Files

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$ ---- Attachments: Standard W8X10 ---------------100 1 0 1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000110 1 1 0 W8X10 WSHAPES9 7.8900 3.9400 0.1700 0.2050 0.0000 0.0000

From Appendix A1 The GTBP File Format

100 ID type Profile_ID OffsetX OffsetY RotX RotY RotZ Extension110 Profile_ID Shape Mirrowed Name Table values[6]

int Profile_ID: Matches with Profile_ID in Attachment (100)int Shape: 1: I, 2: tube, 3: channel, 4: T, 5: 2L, 6: L, 100: Arbitrary

120 Profile_ID type X1 Y1 X2 Y2 CX CY THICK

$ ---- Attachments: Custom W8X10 ---------------100 1 0 1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000110 1 100 0 W8x10-Flanges Custom 7.8900 3.9400 0.0000 0.0000 0.0000 0.0000120 1 0 -1.9700 3.8425 1.9700 3.8425 0.0000 0.0000 0.2050120 1 0 -1.9700 -3.8425 1.9700 -3.8425 0.0000 0.0000 0.2050

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GTSTRUDL

Issues with Omitted Lines

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Omitting attachment lines that are not welded introduces twoconcerns. They may or may not affect your resultsengineering

judgment must be exercised.

Issue 1: If an unwelded and therefore un-modeled part of the

attachment were to translate in theZ direction (into the baseplate) or the base plate were to deflect in +Z direction in anarea where an omitted line was would cause aninconsistency between the physical structure and themathematical model.

Issue 2: An extension model could not be created for the un-modeled part of the attachment, effectively precluding usingthis method for unwelded portions of the attachment.

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GTSTRUDL

How to Model Unwelded Attachment Sections?

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The edge of a plate butted against but not welded to abase plate should transfer compressive force to thebase plate, but not tension or shear (ignoring friction)forces and no moments. This condition will bereferred to as Contact Only.

Two components in GTSTRUDL can model this typeof action: Nonlinear Spring (NLS) elements and TYPE

SPACE TRUSS members declared asCOMPRESSION ONLY with the NONLINEAREFFECTS command.

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GTSTRUDL

Modeling Contact Only with NLS

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Nonlinear springs are already used to model the

compression-only bearing surface, in much the sameway as is needed for Contact Only, exerting only +Z forcewithout shear. However, NLS elements add morecomplexity, requiring curve data and element stiffness

assignments like the bearing surface NLS:NONLINEAR SPRING PROPERTIES

CURVE 'BearSurf' FORCE0.0 0.0 -3907664.702093 -10.0

END OF NONLINEAR SPRING PROPERTIES

NONLINEAR SPRING ELEMENTSINCIDENCES

'S1 ATTACHED TO JOINT 1STIFFNESS'S1' Z CURVE 'BearSurf' FACTOR 0.06250

END OF SPRING DATA

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GTSTRUDL

Modeling Contact Only with Compression Only

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TYPE SPACE TRUSS members designated asCOMPRESSION ONLY with the NONLINEAR EFFECTScommand will also transfer only +Z resistance withoutshear or moments. For several reasons, compression

only members was decided as the modeling method:

1. Simple, easy to understand commands

2. Able to be viewed in GTMenu

3. Less complicated internal nonlinear processing

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GTSTRUDL

Stiffness Connection between Contact OnlyAttachment and Base Plate

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Both the compression-only and NLS methods need aspring constant to represent the resistance to

compression between the Contact Only attachmentand the base plate. This resistance can be viewed asthe transverse compression of the base plate due totheZ force applied by the Contact Only attachment. Aspring constant equal to a short, stubby steel member

was chosen to model the transverse stiffness of thebase plate.

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GTSTRUDL

Implementing Contact Only in theBase Plate Wizard

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A Contact Only designation has been added toattachment lines, along with a lines start and end location

and its thickness. Because any part of an attachment may

be Contact Only, any attachment with Contact Only willmake that attachment Arbitrary, instead of wide flange,channel, etc. More on Arbitrary vs. standard profiles later.

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GTSTRUDL

Contact Only Modeling Rules #1 and #2

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#1 - If a joint is part of both welded and unwelded lines, it isconsidered to be welded. Note: this should only occur at lineends.

#2 - Base plate joints along a Contact Only line have new jointscreated plate thickness above (+Z) them, corresponding to thetop of the plate.

$ ---- Base Plate Wizard user defined data ----------------------

$ Plate: 4.000 in X 6.000 in x 0.5000 in Thickness = 0.5

$ ---- CONTACT ONLY joints and connecting members ----

JOINT COORDINATES

36 1.723 1.637 0.250; 37 1.723 3.000 0.250; 38 3.319 1.637 0.250

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GTSTRUDL


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#3 - Compression-only members (TYPE SPACE TRUSS)are added between the plate joints and the new ContactOnly joints.

#4 - AX equal to MeshSize*MeshSize is assigned to thenew members.

TYPE SPACE TRUSS

MEMBER INCIDENCES

25 36 13; 26 37 18; 27 38 14

MEMBER PROPERTIES AX 1.00000025 TO 27

NONLINEAR EFFECTS

COMPRESSION ONLY MEMBERS 25 TO 27

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GTSTRUDL


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#5 - If the attachment is modeled as a Rigid Footprint,then the RIGID SOLID includes the new Contact Only

joints, but not the plate joints.

#6 - If the attachment is modeled as 2D finite elements(extension), then the first row of the extension elementsare incident to the new Contact Only joints, not theplate joints.

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GTSTRUDL

Simple Example

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Create an 8 x 10 plate with a

W8X10 centered, with a 1 mesh.

Generate a .gtbp file and an inputfile and run it.

View in GTMenu, noting theRIGID BODY display.

Edit the attachment and set theweb as Contact Only (unwelded).

Generate a .gtbp file and an input

file and run it.

View in GTMenu, noting theRIGID BODY display.

Compare the two .gtbp files.

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GTSTRUDL

Simple Example: Generate files

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Save the fully welded standardprofile into Simple.gtbp andthen create an input fileSimple.gti. Check theProcess Input File box to be

able to view the model inGTMenu.

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GTSTRUDL

Simple Example: View in GTMenu

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GTSTRUDL

Simple Example: SetWeb as Contact Only

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On the Attachment page, edit theattachment by double-clickingthe column, then click the Edit

Weld Status button.

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GTSTRUDL

Simple Example: Select Web and Change Status

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Note that the web is marked as line1. Click the 1 in the Line #

column. Line 1 becomes dashed,indicating its selected.

In the Tools menu, select Set selected

lines as Contact Only. Line 1 returnsto a solid line, but is now rose colored,

indicating that the web is nowconsidered Contact Only.

Click the OK button to accept thenew weld status.

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GTSTRUDL

Simple Example: Accept Contact Only Change

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When you return to the Edit

Attachment dialog, the webline will still be blue. Clickthe OK button at the bottomof the dialog to commit thenew weld status.

GTSTRUDL

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GTSTRUDL

Simple Example: Generate Contact Only Files

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When a standard profile has Contact Onlylines, it must be stored as an Arbitrary

profile. This dialog informs you of that andalso offers two renaming options. Click theNO button (reject the suggested new name)to bring up the New Attachment Namedialog.

You can select from the existingtables or type in a new name.Type in a new profile name. 39character limit for both names.

GTSTRUDL

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GTSTRUDL

Simple Example: View Contact Only in GTMenu

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Note the web is now modeled as a row of joints above the mid-plate joints.These new joints are plate thickness in the +Z direction and the RIGIDSOLID includes the new joints and not the plate joints.

GTSTRUDL

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GTSTRUDL

Simple Example: Geometry Close-up

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$ ---- CONTACT ONLY joints and connecting members ----

JOINT COORDINATES

100 4.000 2.000 0.250; 101 4.000 3.000 0.250;

TYPE SPACE TRUSS

MEMBER INCIDENCES

81 100 23; 82 101 32;

MEMBER PROPERTIES AX 1.000000

81 TO 87

NONLINEAR EFFECTS

COMPRESSION ONLY MEMBERS 81 TO 87

Only Z force (which is FXfor the members) is carriedby the truss members (81and 82 in this picture) andonly a compressive force.If joints 100 and 23 move

away from each other, themember 81 transmits noforce.

GTSTRUDL

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GTSTRUDL

Simple Example: Compare .gtbp Files

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Simple.gtbp

$ ---- Attachments: 1 attachments specified ---------------100 1 0 1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000110 1 10 W8X10WSHAPES97.8900 3.9400 0.1700 0.2050 0.0000 0.0000

SimpleContactOnly.gtbp$ ---- Attachments: 1 attachments specified ---------------

100 1 0 1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000110 1 1000 W8x10-FlangesPartiallyWelded7.8900 3.9400 0.0 0.0 0.0 0.0120 1 40.0000 -3.8425 0.0000 3.8425 0.0000 0.0000 0.1700120 1 0-1.9700 3.8425 0.0000 3.8425 0.0000 0.0000 0.2050120 1 00.0000 3.8425 1.9700 3.8425 0.0000 0.0000 0.2050120 1 0-1.9700 -3.8425 0.0000 -3.8425 0.0000 0.0000 0.2050

120 1 00.0000 -3.8425 1.9700 -3.8425 0.0000 0.0000 0.2050

Attachment type ( 1 = W shape, 100 = Arbitrary)ProfileTable nameLine type (0 = welded, 4 = Contact Only)

GTSTRUDL

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GTSTRUDL

Example 2: Partially Welded Channel

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Pattern 1 Pattern 2

Compare results from a fullywelded channel (C8x11.5) withresults from two partially weldedchannels welded with thepatterns shown.

GTSTRUDL

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GTSTRUDL

Example 2: Plate with Anchors and Loads

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Loads are applied at theend of 10 2D

extension, creating MX(loads Down and UP)and MY (loads Left andRight).

GTSTRUDL

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GTSTRUDL

Example 2: Create Custom Attachment

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Since the weld patterns do not match the standard profilelines (flanges and web), a custom attachment is requiredwith the line definition matching the weld pattern. Thecustom attachment below (MyChannels::C8x11.5-Parts2x4) breaks the flanges into 2 parts and the web into

4 parts.

110 1 100 0 C8x11.5-Parts2x4 MyChannels 8.0000 2.2600 0.0 0.0 0.0 0.0120 1 0 -0.4610 -3.8050 -0.4610 -1.9025 0.0000 0.0000 0.2200120 1 0 -0.4610 -1.9025 -0.4610 0.0000 0.0000 0.0000 0.2200

120 1 0 -0.4610 0.0000 -0.4610 1.9025 0.0000 0.0000 0.2200120 1 0 -0.4610 1.9025 -0.4610 3.8050 0.0000 0.0000 0.2200120 1 0 -0.4610 3.8050 0.6690 3.8050 0.0000 0.0000 0.3900120 1 0 0.6690 3.8050 1.7990 3.8050 0.0000 0.0000 0.3900120 1 0 -0.4610 -3.8050 0.6690 -3.8050 0.0000 0.0000 0.3900120 1 0 0.6690 -3.8050 1.7990 -3.8050 0.0000 0.0000 0.3900

GTSTRUDL

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GTSTRUDL

Example 2: View Custom Attachment

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This is the view you would seein Edit Weld Status. Createseparate .gtbp files for eachpattern.

Then write and run the .gtifiles and compare theResultsSummary files.

GTSTRUDL

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GTSTRUDL

Example 2: Results Comparison

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All Welded Pattern 1 Pattern 2

Von Mises 15675 18658 31578S1 17580 19951 35413

S2 -18089 -20309 -34347

B1 612 607 614

B2 701 703 646

GTSTRUDL

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GTSTRUDL

Attachments in .gtbp and the Attachment File

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The .gtbp and Attachment File formats are described inAppendices A1 and A2 of the Base Plate Wizard UserGuide. In addition, examples of custom attachments areshown in the file SampleUserDefinedAttachments.txt in

the \GTStrudl\xx\BasePlate folder ( =

C:\Program Files (x86) or your alternative location, andxx = the version number).

Custom attachments built on a standard profile are simple,

as we have seen. The next slide shows the standardprofile linesif they match your welds it is simple to createa partially welded attachment file.

GTSTRUDL

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GTSTRUDL

Standard Profile Lines

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This the line layout with line numbers for the standard profilesfrom the GTSTRUDL AISC 9thEdition tables. The Edit WeldStatus dialog easily lets you change the status of anyindividual line to Contact Only. If only part of a line is ContactOnly, then you will need to create a custom Attachment File.

GTSTRUDL

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GTSTRUDL

Custom Attachments in the Attachment File

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$ In the AttachmentFileTABLE 'MyChannels'$ Name NumberOfLines100 C8x11.5-Pattern2 8$ X1 Y1 X2 Y2 THICK Type

$ ------- ------- ------- ------- --------- -----0.4610 -3.8050 -0.4610 -1.9025 0.2200-0.4610 -1.9025 -0.4610 0.0000 0.2200 4-0.4610 0.0000 -0.4610 1.9025 0.2200 4-0.4610 1.9025 -0.4610 3.8050 0.2200

$ In the .gtbp file110 1 100 0 C8x11.5-Pattern2 MyChannels 8.0000 2.2600 0.0 0.0 0.0 0.0120 1 0 -0.4610 -3.8050 -0.4610 -1.9025 0.0000 0.0000 0.2200120 1 4 -0.4610 -1.9025 -0.4610 0.0000 0.0000 0.0000 0.2200120 1 4 -0.4610 0.0000 -0.4610 1.9025 0.0000 0.0000 0.2200120 1 0 -0.4610 1.9025 -0.4610 3.8050 0.0000 0.0000 0.2200

GTSTRUDL

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GTSTRUDL

Export Anchor Results for Capacity Anchor Check

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The new ANCHOR commandsin GTSTRUDL 32 need theanchor geometry and resultsto check anchor capacity byAppendix D of the ACI code.The ability to extract this data

has been added to the AnchorResults dialog. Click the WriteANCHOR LOADS button tocreate a file with the geometry(optional) and results in theformat required by the

ANCHOR CONFIGURATIONcommand.

GTSTRUDL

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GTSTRUDL

Generated ANCHOR CONFIGURATION Commands

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ANCHOR 1 X 1.000 Y 1.000 TYPE 'Anchor1'

ANCHOR 2 X 9.000 Y 1.000ANCHOR 3 X 1.000 Y 9.000

ANCHOR 4 X 9.000 Y 9.000

LOAD 'Down'

1 VX 113.9 VY 257.7 TENSION 34.7

2 VX -99.7 VY 243.8 TENSION 22.2

3 VX -119.1 VY 256.5 TENSION 506.0

4 VX 104.9 VY 241.9 TENSION 631.2

END LOAD DATA

LOAD 'Up'

1 VX -119.1 VY -256.5 TENSION 506.0

2 VX 104.9 VY -241.9 TENSION 631.2

3 VX 113.9 VY -257.7 TENSION 34.7

4 VX -99.7 VY -243.8 TENSION 22.2END LOAD DATA

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