In many problems, it is convenient and sometimes necessary to model beam and shell elements at a geometric location that does not match the actual physical location. Such cases are common when flanges or surfaces for shell and beam elements with varying cross-section properties have to be aligned. Another common instance is when beams are used as stiffeners for shells. It is most convenient to model the beam elements by sharing the shell nodes at the midsurface of the shell, as shown in part (a) of figure below. The fact that the beam is actually offset by half the plate thickness and half the height of the beam section will have to be achieved by providing a suitable beam offset as shown in part (b) of figure below.
The elements are specified at the original position in the model and the offset vectors at the nodes of the element are specified within the correspondent structural element. The current nodal offset is applied to each node of the offset element to calculate the offset element position.
All nodal vectors on the post file are calculated and depicted at the original nodal positions. This allows visual compatibility when elements with offsets and elements without offsets are in the model. Element quantities like strains and stresses on the post file are calculated based on the offset element geometries.
