Compared to the SAP2000 standard bridge design tools available from the Define menu > Bridge Loads commands, the Bridge Modeler utility provides further advances and is easier to use when designing complex bridge structures. An additional license is required for the Bridge Modeler (see the Options menu > Request License command for more information).
Quick Start
The Bridge Modeler can be used to quickly generate a bridge model. In its simplest form, three steps are involved:
Define Layout Lines
Define Bridge Deck Sections
Define Bridge Objects
With these three steps, SAP2000 can generate a bridge model using default definitions. After the bridge model has been built, the bridge analysis can be performed.
Note: Some of the
Define menu > Bridge Loads and Bridge
menu commands achieve the same result. Specifically, the following
command pairs function identically:
Define menu > Bridge Loads > Lanes and
Bridge menu > Lanes
Define menu > Bridge Loads > Vehicle Classes and
Bridge
menu > Vehicle Classes
Define menu > Bridge Loads > Vehicles and
Bridge menu > Vehicles
Define menu > Bridge Loads > Bridge Responses and
Bridge menu > Bridge Responses
In-Depth Process Using Bridge Modeler
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.
Enable the Bridge Modeler. If the commands on the Bridge menu are not available, click the Options menu > Request Module License command and select the Bridge Modeler item from the submenu.
Orient the model to
the coordinate system. Click the Bridge menu
> Layout Lines command to access the Define Bridge Layout Line form and
define a layout line. The layout line specifies the orientation of the
bridge relative to the coordinate system. The placement of bridge
objects (e.g., abutments, columns, bents, hinges, spans) is accomplished
relative to the layout line. Click the Set Preferences
button on that form 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 and the Bridge Layout
Line Vertical Layout Data 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 6 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
6 to adjust bridge alignment rather than using these two buttons to adjust
the layout line.
Specify bridge supports. Click the Bridge menu > Abutments command to access the Define Bridge Abutments form and define bridge abutments. Click the Bridge menu > Bridge Column Supports command to display the Define Bridge Foundation Springs form and define column supports for the model.
Define the deck sections. Click the Bridge menu > Deck Sections command to display the Define Bridge Deck Sections form. That form provides access to another 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.
Define the bent assembly. With the bridge column supports and deck section specified, click the Bridge menu > Bents command to display the Define Bridge Bents form. Use that form to access another form to 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.
Add hinges/expansion joints. Click the Bridge menu > Hinges (Expansion Joints) command to display the Define Bridge Hinges (Expansion Joints) form. Use the form to access the Bridge Hinge (Expansion Joint) Data form and specify the type of hinge, the bridge restrainer, and the location of the expansion joints.
Add parabolic shapes, curves, or slopes to the alignment of bridge segments. If necessary, click the Bridge menu > 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.
Build the bridge model. Click the Bridge menu > Bridge Objects command to display the Define Bridge Objects form. Use that form to access the Bridge Object Data form, which has the options needed to build the bridge model. The options can be used to specify a single span from the starting abutment to the ending abutment, or to specify bridge segments using station locations along the bridge alignment, which can be adjusted by specifying vertical and horizontal offsets for the specified bridge segment(s). The buttons available on the form (e.g., Modify/Show Span Definition, Modify/Show Abutment Definitions and so on) provide easy access to the forms used to define the elements comprising the bridge objects, making adjustments to the bridge model quick and easy. In addition, those forms provide access to additional forms that can be used to define prestress tendons for the model.
Generate the bridge model from the bridge object. Click the Bridge menu > Update Linked Bridge Model 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 Bridge Modeler (i.e., the commands on the Bridge menu). Using the Convert to Unlinked Model option also will create the object-based model, but will then "disconnect" the model from Bridge Modeler. Thus, an unlinked model can no longer be modified or updated using Bridge Modeler. However, an unlinked model can be edited using SAP2000's other menu commands (e.g., Edit menu, Draw menu).
After the bridge model has been built, the bridge analysis can be performed.
See Also