Haunch — where it appears
The moment that goes round the corner
At a rigid knee the bending moment does not stop at the end of the beam. It turns and runs down the column, and in the same instant the beam's shear becomes the column's axial force — while the block of steel that has to carry the turn appears on no member diagram anywhere.
The section that changes along the span
A prismatic beam is checked where the moment is largest, and everyone knows where that is. A tapered one is not, because the capacity is moving too — and for a cantilever with a load at its tip the governing station is exactly where the depth has doubled, with no length, no load and no material in the answer.
Named alongside it
The objects these essays reach for when they reach for this one.
Bending momentContinuityContraflexureDeflectionFree body diagramFully stressed designMoment connectionMoment diagramPanel zonePortal frameSecond moment of areaSection modulus