FE Civil Exam Prep 39, Shear and Moment Diagrams — Sign Convention Trap
Aug 5, 2026
This podcast is made by Ran Chen, who holds an EA license, Insurance and Securities licenses (Series 6, 63, 65), and the CFP® designation. He is passionate about opening access to high-quality exam preparation resources and helping learners prepare more effectively for professional certification exams.
In this episode you will learn:
- The NCEES sign convention: Positive shear is down on the right face of a cut, and positive moment causes a beam to sag like a smile.
- The graphical relationship where the slope of the shear diagram equals the negative of the distributed load intensity (dV/dx = -w).
- The critical shear-moment relationship: The slope of the moment diagram equals the shear force value (dM/dx = V).
- How to find maximum moment: The maximum bending moment always occurs at the point where the shear force diagram crosses zero.
- The concentrated moment trap: A clockwise applied moment causes an immediate upward jump in the moment diagram, a common point of confusion.
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