It is apparent that my version of STAAD is performing calculations backwards for uniform member loads defined in local member coordinates, and uniform member loads defined in global coordinates. See the attached screenshots and .std files for example. The example building is 30.35m wide.
Using loads defined in global coordinates (test.std), the displayed load direction is correct, but the calculated vertical reactions are incorrect (simple hand calculation says (30.35m) * (5.16 kN/m) / (2) = ~78.3 kN)
If I define the loads in local member coordinates (test2.std), displayed load directions are again correct, but the calculated reactions appear to be calculated as though the load was defined in global coordinates (they agree with the hand calculation above).
I am currently downloading the most recent version of STAAD to see if the problem will be fixed. I'm really just looking for someone more experienced to validate these findings. If I am correct, then I have many analyses to review/fix, and perhaps Bentley can fix the bug.
UPDATE: I get the same, seemingly incorrect results, in the newest version of STAAD. Any ideas? Please let me know if I can clarify anything with the problem I'm having.