If you want to design a member with one or more shapes that are not available from the Structural Member Catalog and cannot be created using the Structural Member Style Wizard, you can use the Style Manager to create custom shapes.
When you create a custom shape, you can define three separate geometries (Low Detail, Medium Detail, and High Detail) to accommodate the different levels of detail in different display representations (for example, Plan Low Detail, Plan, and Plan High Detail). The geometries for the new shape can be set entirely from linework in the drawing area, or you can use an existing custom shape definition as a template and edit it to redefine any of its geometries.
Hollow core concrete plank display representations example
Once you have created a custom shape, it is added to the list of Structural Member Shape Definitions in the Style Manager. You can then create a new style from the shape, or you can assign the shape to an existing structural member style by adding it as a component in the design rules of the style. You can also edit, copy, paste, and purge shape definitions just as you can other styles.