The loading is In-Plane only (uniaxial tension test). If I understand correctly, the question becomes:

For In-Plane loading, when using reduced integration on the SHELL281 element with 5 integration points, there will still be 5 integration points through the thickness of the element. Because the loading is In-Plane only, one expects that the stress results will be the same no matter which layer in the shell element they are taken from (TOP, MIDDLE, or BOTTOM). When using the Options for Output in ANSYS and selecting the MIDDLE LAYER of the SHELL281 element, does ANSYS ordinarily compute the maximum stress output from the MIDDLE LAYER as the maximum of the 5 integration points, the average of the 5 integration points, or the extrapolation of the stress to the nodes?

Thank you so much!