ProSteel/ProStructures uses a file called pro_st3d.lin
This file controls the line types that you can use within ProSteel/ProStructures. The Line type that a user would like to use should be added to this file in order for ProSteel/ProStructures to read and use it.
By default it is located under C:\Program Files\Bentley\ProStructures\V8i_Version\AutoCAD Version\Prg.
Changing Line Styles from the ProSteel Options to Reflect in 2D Drawings [TN]
Assigning Line Styles from the Detail Style to Reflect in 2D Drawings [TN]