Applies To
	Product(s):	STAAD.Pro
	Version(s):	ALL
	Environment:	ALL
	Area:	Modeling Solutions
	Subarea:	Other
	Original Author:	Bentley Technical Support Group

See the attached image and notice that Infilled Plates 470 and 471 do have same orientation but different local axes.

The vector pointing from I to J defined to be local x- axis.
The cross-product of vectors IJ and JL defines a vector parallel to the local z-axis, i.e., z = IJ x JL
The cross-product of vectors z and x defines a vector parallel to the local y- axis, i.e., y = z x x.
The origin of the axes is at the center (average) of the four joint locations (three joint locations for a triangle).



Please look at the model and you will see the logic is as stated. For your square plates, the local X axis is parallel to the line defined from Node A to Node B.