Parametric Bridge Engineering

Access an Example Steel Bridge Model

Follow the steps below to open the Steel I-Girder Training Example.

1. Log in to your account and locate Project in the top-right corner.

   
2. Click Project, then click NEW in the top-left corner.

   
3. Under Example Project, click New Project within Steel I-Girder Training Example.

   

   
4. Provide a name for your project and open the example.

   

   

The initial download of the library components takes approximately 2 minutes 30 seconds. Subsequent openings of the same project are noticeably faster because OpenBrIM library objects are cached in your browser; loading then takes less than 2–3 seconds.

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OpenBrIM Parametric Modeling

This section demonstrates how OpenBrIM's cloud-based parametric approach updates every connected output (3D model, FEA model, drawings, reports) when you change a single input.

In the steps below, you will modify the Web Depth parameter of a girder in the spreadsheet. Both the 3D model and the FEA model will update automatically.

1. Click the DATA button in the bottom-middle of the screen to open the spreadsheet.

   

   

   • To resize the spreadsheet, click and hold the DATA button with the left mouse button and drag.
   • To close the spreadsheet, click the DATA button once.
2. Click Plate Girder under Superstructure in the workflow tree. All project girders and their parameters appear in the spreadsheet.

   
3. To compare the FE model before and after the change, open the sliding menu in the top-left corner and click FEA to switch to the Finite Element view. The menu also offers MODEL, CAD, DOCS, SUPPORT, and USER SETTINGS.

   

   

   

   Zoom with the mouse scroll wheel. Pan by holding the scroll wheel down while moving the mouse. To recenter the view, click the Zoom Extents button in the top-right corner; after selecting an object, Zoom Extents orbits the view around that object. Rotate by dragging with the left mouse button.

   
4. The current Finite Element model uses an 84 in web depth. To change it for girder G4, click the Web Depth cell for that girder and enter 55 inches.

   

   

   After the change, the 3D model and Finite Element model take roughly 10 seconds to refresh. OpenBrIM recompiles using your inputs to regenerate the 3D model, FEA model, CAD drawings, and dynamic reports (such as the quantity report) so all outputs stay in sync.
5. The new Finite Element model now reflects the updated web depth.

   
6. Open the sliding menu again from the top-left corner and click MODEL to switch back to the 3D view.

   
7. The change is visible in both the 3D and Finite Element views.

   

For a full description of girder plate dimensions, see Plate Girder [SIG].

For a worked example, see Plate Girder [EX1-SIG].

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OpenBrIM Spreadsheets: Excel-Like Functionality with Parametric Dependencies

This section shows how OpenBrIM spreadsheets behave like Excel — cells can reference one another to keep related parameters in sync.

Cross-frame skew, roadway skew, and support-line skew are independent inputs by default, so the same value must be entered in three places. The steps below link them so that changing the support-line skew updates the others automatically.

1. Click Support Line under Bridge Geometry in the workflow to access the skew angle parameter.

   
2. To change the skew angle of Abut1, click the corresponding cell (marked in red).

   
3. With the skew angle of Abut1 set to 0, the bridge appears as shown.

   
4. With the skew angle of Abut1 set to −15°, the bridge appears as shown.

   

The cross-frames are no longer aligned with the support line.

To link them parametrically:

1. Copy the support line's skew angle value with Copy Parameter.
2. Paste the parametric expression into the cross-frame's skew angle.
3. The cross-frame skew now follows the support line skew automatically.

1. Click the skew angle cell for Abut1. Click the three-dot menu that appears on the right side of the cell, then choose Copy Parameter. The skew angle parameter (not the value) is copied.

   

   The parameter copied: =Abut1.s_skew
2. Expand Cross Frames under Superstructure in the workflow, then click Cross-frame K Top to access its parameters.

   
3. Click the skew angle cell for CFTK1. Open the three-dot menu that appears on the right side of the cell and choose Paste.

   

   You can also paste the copied parameter into the active cell with CTRL+V.
4. Repeat the paste for CFKT28 and CFKT29. The cross-frames are now aligned with the support line.

   
5. Cross-frame skew angles are now parametrically linked to the support-line skew, so changing one updates the others.

   

The cross-frame skew now references the support line's skew the way one Excel cell references another. OpenBrIM cells accept arithmetic, functions, and logical operators, so more complex equations are supported. See Mathematical Functions in the ParamML documentation.

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Aligning Roadway with Skew Angle

Use the same Copy Parameter approach to align the roadway with the skew angle of the support line.

1. Expand Superstructure Attachments in the workflow and click Roadway to access the roadway alignment parameters.
2. Open the three-dot menu on the right of the Roadway Dimensions cell and click Edit.
3. Paste the skew angle copied from Abut1 into the Skew parameter at station 0.