Go to the Edit menu, and choose Edit Input Command File.
1) Locate the line which says SET Z UP. Remove that line, or, put an asterisk in the first column of that line.
2) After all the member incidences have been defined, add the following command,
PERFORM ROTATION X -90
3) For the JOINT LOADS, all loads that are applied along FZ should be changed so they are along FY.
4) For the JOINT LOADS, all loads that are applied along FY should be changed so they are along negative FZ.
5) For MEMBER and ELEMENT LOADS, all loads which are applied along GZ should be changed so they are along GY.
6) For MEMBER and ELEMENT LOADS, all loads which are applied along GY should be changed so they are along negative GZ.
Similar switching has to be made wherever parameters for steel and timber design have been specified, such as KY, KZ, LY and LZ.
Save and exit the STAAD editor.
The orientation of the structure should now look proper on the screen.