Null elements are used to create a rigid connection between two elements that do not have a common node.
For a null element, the normal thickness t = 0 mm. The shear thickness t* must be greater than zero for each element. Determination of the shear thickness t* is required for the null elements that are not affected by 'normal' elements (t > 0) along their entire length.
Cross-Section Properties Software
Section properties, stress analysis, and plastic design of open and closed thin-walled cross-sections