Hi Yijia,
I think part of the problem is that a structural member's rotation in regards to the ACS is actually along its length; i.e., the member line connecting the P & Q points (which are linked to GC Point nodes). So in the case of a column it would essentially be rotating from vertical to some other angle, whereas beams typically rotate about the Z axis (which in most cases is not unusual).
The Rotation property itself is a numeric data type which is why it doesn't connect with an ACS. I'm not sure how we could accomplish rotating a member about itself in some other fashion, so as Volker mentioned perhaps it's best to log a Service Request with support so this can be filed as an Enhancement request.
I think part of the problem is that a structural member's rotation in regards to the ACS is actually along its length; i.e., the member line connecting the P & Q points (which are linked to GC Point nodes). So in the case of a column it would essentially be rotating from vertical to some other angle, whereas beams typically rotate about the Z axis (which in most cases is not unusual).
The Rotation property itself is a numeric data type which is why it doesn't connect with an ACS. I'm not sure how we could accomplish rotating a member about itself in some other fashion, so as Volker mentioned perhaps it's best to log a Service Request with support so this can be filed as an Enhancement request.