Currently there is no option in Staadpro to get the deisgn of Curved Beams as well a plates apart from splitting the member up into a number of nodes. But, there is option to draw curve beam elements. Bentley should resolve this issue to induce the effects of curved elements and get design output in Staadpro since, the other software developers (e.g csi) have taken initiatives to get design results of curved beams & shell elements which would certainly create a drawback for staad users.
The curved beam implementation in STAAD.Pro has limitation due to which we recommend using segments of straight members instead. The limitations are explained in detail at the following wiki communities.bentley.com/.../8353.limitations-of-the-curved-beams-in-staad-pro-tn I will however pass on your request to the product management so that this can be considered for future development.