Each Beam possesses a reference axis which serves the precise connection of Beams for clean intersections and establishes hotspots and edges for selecting, moving and transforming Beams. Its direction determines the beam’s “left” and “right” surfaces for the purpose of applying surfaces in the Model Panel of Beam Settings.
See Beam Model Panel.
The direction of the reference axis follows your cursor as you drag it to draw the beam. (To see the arrow on the beam that indicates the axis direction, turn on View > On-Screen View Options > Walls and Beams Reference Lines.)
By default, the reference axis runs in the center of the Beam’s upper face. You can also offset it from the center by any distance (for example, if you are using a beam with an asymmetrical profile): enter a value in the Offset field, in the Geometry and Positioning panel of Beam Settings.
In the 3D window, the reference axis of a selected Beam is shown in a separate color: you can change this color using the “Reference Lines in 3D” setting at Options > Work Environment > Selection and Element Information.