The topping joint width is defined as the smallest value of b_topping and b_beam, measured a distance of 𝛿 from the bottom of the topping (or top of the beam, as it is the same point). The tolerance is set to a very small value (1.0e-6) to take into account if the elements may have been imported (in case of hollowcore dwg-profiles) by not being drawn exactly perfect, or at a very smal angle.

b_joint = min (b_topping, b_beam)

In some extreme cases the picture would look like this (projected quite excessive).

That is why some imported cross sections may have very small value for b_joint. In that case go back and verify the input cross section from the dwg-import.