To set the structural model representation
- On the ribbon, click Structure tab
Parts panel Line Model drop-down. 
- Click one of the available model types.
To create a structural member
- On the ribbon, click Structure tab Parts panel Member.
- In the drawing area, specify the start point.
- In the drawing area, specify the end point.
- The prompt is redisplayed to enable you to create multiple members. Press Enter when finished creating members.
To restore (undo changes to) a structural member
- On the ribbon, click Structure tab Cutting panel Restore Member.
- In the drawing area, select the member that you want to restore.