Concept
Bending moment
3 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
The hinge put in on purpose
An arch with two pinned feet cannot be solved by statics. Add a third hinge at the crown — deliberately weakening it — and the whole structure falls out of one moment equation.
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.
The train that is worse than its heaviest axle
An influence line says where to stand one load. A vehicle is several loads at fixed spacings, and the worst arrangement never puts the heaviest one at the peak.
Named alongside it
The objects these essays reach for when they reach for this one.
Axle trainBarre ruleDeterminacyFree body diagramHorizontal thrustInfluence lineLoad pathMoment envelopeMoving loadPattern loadingResultantSaint-Venant's principle