Lines and arcs can be converted into beams and curved beams.
Access the command
On the Objects tab 
Beams panel, click
(Beam, from line).
Command line: _astm4CommLine2Beam
Convert lines to beams
- On the Objects tab Beams panel, click
(Beam, from line).
- Select one or several lines and arcs to convert and press <Enter>.
- Delete or keep the lines by choosing Y (Yes) or N (No).
- Press <Enter> to finish.
- The selected lines and arcs are converted.