You can create your own customized 3D girders by modeling them in Inventor (*.ipt file) and bringing them into InfraWorks. There are two requirements to use 3D girders, Depth1 and Depth2.
Select the bridge and select the girders to modify.
In the Stack, select the type of girder.
The Select Components dialog displays.
Search for a 3D girder.
Select one of the 3D girders.
The selected girder changes to the 3D girder.
To find the 3D Super Tee girder in the content library
In the toolbar, click Manage Content
(Style Palette) to open the Style Palette.
Select the Parametric Models tab Bridge
Girders
Super Tee 3D (the provided 3D girder).
Double-click the style to display the Configure Parameters dialog.
Here you can duplicate the 3D girder for further customization, see all of the parameters, part types and UI appearance tabs for the 3D Girder, as well as access the Inventor model, by clicking Show in Explorer.
Depth1 and Depth2 must have a green check for the girder to work properly.