What is the sign convention

POSITIVE NEGATIVE
Axial force
Bending moments

The bending moment is drawn on the tensile side of the member

  • If the upper side (z’ > 0 or y’ > 0) is subjected to tension, the bending moment is positive.
  • If the lower side (z’ < 0 or y’ < 0) is subjected to tension, the bending moment is negative.
Shear force

The sign of the shear force depends on the variation of the corresponding moment.

  • Ascending curve for the bending moment → shear force is negative
  • Descending curve for the bending moment → shear force is positive
Reactions

(signs for reactions are shown in Diamonds 2020 or newer)

The sign of the reactions depends on its direction:

  • If the reaction goes in the same direction as the global coordinate system, the sign is positive.
  • If the reaction goes in the opposite direction of the global coordinate system, the sign is negative.

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