Different temperature values, applied to the top and/or bottom fibers of a plate and/or wall structural element, cause deviations in the cross-section simultaneously in the local rotational directions X'r and Y'r of the element plane. Because the plate's local axis system is parallel to the global axis system, the relations X'r = Xr and Y'r = Yr are valid.
For compatibility reasons, the flexural temperature action for a plate element must be defined in the Yr direction, whereas for a wall element it must be defined in the Y'r direction.
A uniformly distributed temperature over the middle plane of a wall structural element causes the elongation of the cross-section simultaneously in the local X' and Y' directions of the element.
For compatibility reasons, the axial elongation temperature action for a wall element must be defined in the X' direction.