Negative Y co-ordinates for imported STAAD file

Question

Why values of Y co-ordinates are in negative when Tekla co-ordinates are compared with staad co-ordinate
after importing a Staad file into Tekla using Import FEM settings?

Answer

This happens because co-ordinate systems of Staad and Tekla Structures are different.

Staad axes in plan -->  

Tekla axes in plan -->  

So while importing Staad file, Tekla Structures matches origin as per Staad and X axis as per Staad, because of which positive z axis in Staad becomes negative Y axis in Tekla and hence positive Z coordinates of staad will be negative Y co-ordinates in Tekla Structures.