I need to analyze a frame whose members have been rotated about the local z axis. Is there anyway to model this situation using STAAD? Can you input a point and define the orientation of the local axis of that point? Or is there some other way to model this situation?
We presume you mean that the member is rotated about the local "X" axis and not the local "Z" axis. When you use STAAD's default coordinate system, the local "X" is the longitudinal axis of the member, and local Z is generally the major axis of the member. So, changing the orientation of a member involves rotation about the local "X" axis, and not the local "Y" or local "Z" axes.
There are a couple of ways to change the orientation.
a) By specifying an angle using the BETA command. This is explained in Sections G.4.2, G.4.3 and TR.26.2 of the STAAD.Pro Help. You may also refer to example 1 of the Examples manual for a sample problem which shows the usage of the command.
b) Using the REFERENCE POINT method. This too is explained in Sections G.4.2, G.4.3 and TR.26.2of the STAAD.Pro Help. Also, in the section Ribbon Control Reference > Specification tab > Reference Point dialog.
In the STAAD.Pro GUI, you may click the right mouse button, select Labels, and switch on Beam Orientation to get a visual representation of the directions the local X and Y axes point to.
Graphically, you can specify the BETA angle from 2 places :
If you go to the Properties page, you will find the Properties dialog box on the right side and it contains a tab called Beta Angle through which the value can be specified.
You can also go to Specification > Beam > Beta Angle in the ribbon menu.
Graphically, you can specify the REFERENCE POINT by going to the Specification > Beam > Beam Reference Point.