Warping
The moment that will not lie flat
A plane cut exposes three actions. A real cut exposes six, and the fourth of them behaves unlike the others — torsion is resisted by a loop of shear, and one slit down the length of a tube destroys it.
The point that is not in the section
A channel loaded down its web twists. To stop it, the load must be applied through a point outside the steel entirely — in the air beside the section, where nothing can be attached.
The beam that fails sideways
A deep narrow beam bending in its strong plane can, at a moment well below its capacity, swing out of that plane and twist. The failure has nothing to do with how much it can carry and everything to do with what is holding it.
Named alongside it
The objects these essays reach for when they reach for this one.
TorsionOpen sectionShear centreShear flowCompression flangeCritical momentEccentricityEffective lengthHollow sectionI-sectionLateral restraintLateral torsional buckling