Revit Architecture
Revit StructureYou can create a structural beam system either by picking the structural supporting elements, such as beams and structural walls, or by sketching the border. After specifying the beam system boundaries, you can specify the beam direction and beam system properties, such as spacing, justification, and beam type. For more information, see Beam System Layout Rules and Patterns.
To create a structural beam system

Structure panel
Beam System 
Structure panel
Beam System
Beam System panel
Sketch Beam System.
Mode panel
Finish Edit Mode.