Bridge Modeler Basic Concepts

Let us first give you a brief overview of the SAP2000/Bridge module (or bridge modeler) available in SAP2000. The bridge modeler enables you to parametrically define several types of girder bridges. This parametric modeling can save a significant amount of work, since you do not need to manually create every single element (frame, shell, etc.) of the bridge. Instead, the bridge is parametrically defined using higher level objects, such as deck section (to describe cross-section of the bridge), layout line (to describe the profile of the bridge both in plan and elevation), etc. and the program creates the low level objects from this parametric definition. The parametric definition is also used to automatically obtain resultant forces acting on the bridge superstructure.

The parametric definition is well suited for bridges that are regular. For irregular bridges, the bridge modeler can be used to develop the core of the model but then it may be necessary to model the irregular features of the bridge manually, outside of the bridge modeler. (In this case, however, the manual changes may get overwritten if the parametric definition is changed and the analysis model is regenerated.)

Based on the above, the typical workflow is to create the model in the bridge modeler first and then enhance it in SAP2000, if and as needed.

For non-girder type of bridges (arch, suspension, cable-stayed, truss, etc.), you could perhaps utilize the bridge modeler to create the deck and substructure portion of the bridge, but the remaining geometry would need to be modeled outside of the bridge modeler. Depending of the specific details of your bridge, you may even find out that the best approach could be to model the entire bridge outside of the bridge modeler.

Other advantages of the bridge modeler include the following:

• ability to generate spine, area and solid models from the same parametric definition

See Also

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The Bridge Modeler enables parametric definition of girder-type bridge systems. Users initiate high-level parametric modeling by defining span length, layout lines, cross section, and other geometric and structural specifications. The Bridge Modeler then assembles frame, shell, and solid objects, and connects them with link elements, to automatically create bridge objects. The Bridge Modeler expedites design by automatically generating, meshing, and analyzing complex bridge models. Templates are also available for several superstructure and substructure design checks.

References

• Aviram, A., Mackie, K., Stojadinovic, B. (2008). Guidelines for Nonlinear Analysis of Bridge Structures in California. Berkeley, CA: Pacific Earthquake Engineering Research (PEER) Center.

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