# In SHAPE-THIN, I want to connect a free-standing cross-section part by means of a null element with the rest of the cross-section. Graphically, this is no problem.For the calculation, however, SHAPE-THIN always asks to specify a thickness t* for the shear calculation.

In chapter 7.2.1 of the SHAPE-THIN manual, you can find the formulas for shear areas and Bredtschem torsional moment of inertia. There, the element thickness t * is in the denominator, so the division by zero would be a problem. For "free" null elements, an equivalent thickness must therefore be defined by the user, for example Example, the thickness of one of the adjacent elements.

Select the null element and select "Effective thickness for shear transfer" in the "Edit Element" dialog box. Then, the input field t * becomes accessible. Then, the calculation is possible.