This form uses the theory of beams under bending, normal stress and shear, also known as Timoshenko beam (Wikipedia).
The solution is based onto a polinomial formula obtained from strain energy V minimization ('Options'->'Show formulae' in the menu to see, relationships enforcing boundary conditions not shown).
To cancel the influence of normal stress and/or shear you may proceed as follows (for all members, but also for some of them):
a) to cancel both set the area of the cross section to a high value (10^3 to 10^6 times the actual value, but watch the results, you might cause numerical instabilities)
b) to cancel shear only leave the area as is and set the shear factor to a low value (10^3 to 10^6 smaller than the actual value)
c) to cancel normal stress only set both the area and the shear factor to a high value, multiplying both by the same factor
When present, the button 'Data' will download the vectors of coefficients (without dimensions) ab,c,...as defined in sheet's formulae. Note that it is up to the user to link the downloaded vectors to the input data: when you download it, the vectors correspond to the data in the sheet as you view it.