it is confusing. when we say the horizontal axis as principle it means local Z? what if the member is vertical. if local Z is principle axis which side is top? is it the side the local Z arrow pointing to? equally confusing is what does it mean when we say vertical axis as principal. it means the local Y axis? thanks
Yes, by default, the member local Y axis is vertical and Z is horizontal, while X axis is oriented along the member length, pointing from start node to the end node. Please see more in STAAD.Pro Help manual, chapter G.4.3 Relationship Between Global and Local Coordinates.
Thanks But sorry. if local Z is the principal axis which side is Top? is the local Y arrow pointing to? same question which side is right hand side for ULR?
Sorry it should be UNR. which side is right side?