Structural Engineering & Statics
where the load goes
Concept

Sign convention

2 essays name this object, across one field. What follows is each of them, and the objects they name alongside it.
2012.57.5shear 7.5moment 22.5the cut, at x = 5nothing was applied here — the internal forces are what the left-hand piece needs

What a cut reveals, and why it was there all along

Cut a beam anywhere and two quantities appear on the face — a shear force and a bending moment. Nothing was applied there. They are what the material was already doing.

internal-forces · internal forces 4 per unit lengthshear16.0moment32.0 at x = 4.00the moment peaks exactly where the shear passes through zero

The diagram is an integral, and that is why it can be drawn by eye

Load, shear and moment are one function and its two integrals. Once that is seen, the diagrams stop being things to calculate and become things to sketch.

internal-forces · diagram relations

Named alongside it

The objects these essays reach for when they reach for this one.

Area ruleBending momentDiscontinuityFree body diagramIntegrationLoad pathMoment diagramSaint-Venant's principleShear diagramShear forceStress resultantTorsion

All concepts