General Process for Creating a Bridge Object

In its simplest form, three steps are involved in creating a Bridge Model using CSiBridge:

  1. Define Layout Lines

  2. Define Bridge Deck Sections

  3. Define Bridge Objects

With these three steps, CSiBridge can generate a bridge model using default definitions. After the bridge model has been built, the bridge analysis can be performed.

Process for Tailoring a Bridge Object

In some cases, more control over the parameters used to define the bridge model may be necessary. The following process is intended to demonstrate the relationship among the various commands and forms that can be used to define the bridge object that is used to generate the bridge model.

  1. Orient the model to the coordinate system. Click the Layout > Layout Lines > Expand arrow command to access the Define Bridge Layout Line form and define a layout line using the Bridge Layout Line Data form.

The layout line specifies the orientation of the bridge relative to the coordinate system. The placement of  bridge objects (e.g., abutments, columns, bents, spans) is accomplished relative to the layout line. Click the Set Preferences button on that form (or click the Layout > Preferences command) to display the Bridge Layout Preferences form and specify the orientation of the North arrow relative to the X axis of the global coordinate system and the discretization (i.e., smoothness) of any curves used in the bridge model.

In rare instances, it may be desirable to adjust the horizontal or vertical alignment of the layout line. Use the Bridge Layout Line Horizontal Layout Data form (or the Horizontal Layout Line Data - Quick Start form) and the Bridge Layout Line Vertical Layout Data form (or the Vertical Layout Line Data - Quick Start form) in such a case. Note that changing the alignment of the layout line adjusts the reference line, and therefore, the placement of bridge objects. Step 8 below explains how to adjust the alignment of deck sections relative to the layout line rather than adjusting the layout line itself.  For the beginner, it likely is better to use the commands identified in Step 8 to adjust bridge alignment rather than using these two buttons to adjust the layout line.

  1. Define the deck sections. Click the Components > Superstructure Item > Deck Sections > Expand arrow command to display the Define Bridge Deck Sections form. That form provides access to the Select Bridge Deck Section Type form that can be used to select a template shape for the deck section and girder assembly.

The templates can be used to quickly model common bridge deck section configurations (e.g., vertical girders, sloped girders, tee beams, and flat slabs, among others). After selecting the shape for the bridge deck section, also specify the section property, material property, the slab and girder thicknesses, and the left and right overhang.

  1. Specify diaphragm properties. Click the Components > Superstructure Item > Diaphragms > Expand arrow command to access the Define Bridge Diaphragm Properties form and define diaphragm properties using the Bridge Diaphragm Property form.

  2. Specify restrainer properties. Click the Components > Substructure Item > Restrainers > Expand arrow command to access the Define Bridge Restrainer  form and define restrainer properties using the Bridge Restrainer Data form. The properties defined in this step are assigned to the bridge model by defining a Bridge Object (see Step 9).

  1. Specify bridge bearings. Click the Components > Substructure Item > Bearings > Expand arrow command to access the Define Bridge Bearings  form and add bearing properties to the model using the Bridge Bearing Data form. The properties defined in this step are assigned to the bridge model by defining a Bridge Object (see Step 9).

  1. Specify bridge supports. Click the Components > Substructure Item > Foundation Springs > Expand arrow command to display the Define Bridge Foundation Springs form and define supports for the model using the Foundation Spring Data form.

Click the Components > Substructure Item > Abutments > Expand arrow command to access the Define Bridge Abutments form and define bridge abutments using the Bridge Abutment Data form. The properties defined in this step are assigned to the bridge model by defining a Bridge Object (see Step 9).

  1. Define the bent assembly. With the bridge column supports and deck section specified, click the Components > Substructure Item > Bents > Expand arrow command to display the Define Bridge Bents form. Use that form to access the Bridge Bent Data form and define the number of columns, the cap beam section property, the length of the cap beam, and the location(s) of the column(s) in the bent assembly. The properties defined in this step are assigned to the bridge model by defining a Bridge Object (see Step 9).

  2. Add parabolic shapes, curves, or slopes to the alignment of bridge segments. If necessary, click the Components > Substructure Item > Parametric Variations command to display the Define Parametric Variations form. Use the form to access the Variation Definition form and specify parabolic and curve adjustments to bridge segment alignments.

  3. Build the bridge model. Click the Bridge > Bridge Objects > Expand arrows command to display the Define Bridge Objects form. Use that form to access the Bridge Object Data form, which has the options needed to assign spans, supports, superelevation, prestress tendons, girder rebar and loads.  Highlighting an item in the Modify/Show Assignments Display Area and clicking the Modify/Show button provides easy access to the forms used to assign the elements comprising the bridge objects.  

  4. Generate the bridge model from the bridge object. Click the Bridge > Update command to create an object-based model based on the various definitions specified in the preceding steps. When the Update Linked Model option is selected in the Action drop-down list, the model can be modified and updated again using any of the commands described in this topic). Using the Convert to Unlinked Model option also will create the object-based model, but will then "disconnect" the model from CSI Bridge. Thus, an unlinked model can no longer be modified or updated using the commands described in this topic. However, an unlinked model can be edited using the Advanced commands (e.g., Edit, Draw, Assign).

  5. After the bridge model has been built, the bridge analysis can be performed.

See Also

Bridge Wizard