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Expansion joint local axes are the same as piping local axes, displayed below in line view with colored arrows. Red arrow points to local +1 (U1) longitudinal direction, green arrow points to local +2 (U2) which is vertical with horizontal piping, and blue arrow points to local +3 (U3), so R1, for example, would be torsional stiffness. The same colored arrow convention with red local 1, green local 2, and blue local 3 can be displayed for local axes of supports, joints, frames, and local axes of links.
Convoluted modeling approach required by other pipe stress software:
