ClearCalcs supports open web steel joists (bar joists) for flat roofs through our Steel Joist Calculator, which adheres to U.S. building standards, specifically the Steel Joist Institute’s SJI 100-2020 and SJI Load Tables.
For a practical demonstration, here’s a worked example detailing the design process of open web steel joists on the roof of a single-story commercial building:
https://www.clearcalcs.com/support/steeljoistsasd-worked-example
Additionally, you might find this overview video helpful:
Open Web Steel Joists - Overview
Feel free to explore these resources, and don’t hesitate to ask if you have any questions! 