I found this problem when I was importing HSS sections from AISC profile file, that the default material for HSS is not 46ksi and all the tube were imported with Fy=50ksi. It was tedious to go and change every HSS material one by one to Fy=46ksi.
Here is the procedure which should be followed in order to avoid this issue:
1. Click Section Properties > Frame Sections
2. Click “Import New Property” button
3. Click “Tube” button
4. Select file to import from computers and structures > SAP2000 folder. File name will be AISC13.pro for AISC 13th Edition in English units and or AISC13M.pro for metric units. (Also sizes per 14th edition is also included in new version)
5. The box will appear with sizes to import. Change the material to A500GrB46 or any material which is required.
Select sizes to import and click ok.
6. The material for all HSS tube will be A500GrB46.