STAAD.Pro Help

G.18.1.4 Force Envelopes

Force envelopes of the member forces FX (axial force), FY (Shear-y), and MZ (moment about local z-axis, i.e., strong axis) can be printed for any number of intermediate sections. The force values include maximum and minimum numbers representing maximum positive and maximum negative values.

The following is the sign convention for the maximum and minimum values:
FX A positive value is compression, and negative tension.
FY A positive value is shear in the positive y-direction, and negative in the negative y-direction.
FZ Same as above, except in local z-direction.
MZ A positive moment will mean a moment causing tension at the top of the member. Conversely, a negative moment will cause tension at the bottom of the member. The top of a member is defined as the side towards positive local y-axis.
MY Same as above, except about local y axis.