I see in the Maxima help file you can instruct the SUPP command to superimpose either the VX and VY for QUAD elements. My question is whether it is possible to request to superposition the principal shear in the quad i.e. sqrt(VX^2 + VY^2)?

Any advice or pointing me in the right direction will be appreciated.

yes, it is possible the superimposed the resultant shear forces in QUAD or in their nodes (QNOD) using an objectiv function in the record SUPP in such a way. A detailed description with input example you can find in the manual MAXIMA chapter 3.11.5 Definition of an Objective Function.
Please note, that here the directions are missung due to the square root.

With kind regards
Sabine Fahrendholz
Senior Product Manager

Dear Sabine, thank you very much! This worked for the superposition part.

If I can ask one more question in this regard, how do I view this result in Graphic? Say the results are stored in lc 2137, I donâ€™t see an option to choose the objective function from the list