This software does the trick for curved steel beam design. It uses a 2-d grillage model for analysis so diaphragm stiffness is accounted for in stress calculations. The learning curve on this one is pretty high--plan to initally spend some time on it. This is probably the only straight/curved steel beam software you'll ever need. The user interface needs a bit of updating. This program utilizes a text-based input file which, to me, means it could be old software, but also may reduce input time on future analysis. It has been a while since I have seen a price quote but my memory tells me it was of the moderate variety.