Upper bound — where it appears
Named by 2 essays across 2 fields — each of them below, with the objects they name alongside it.
After the first yield, which is not the end
A steel beam whose extreme fibre has reached yield has not failed. It has started forming a hinge, and collapse waits until there are enough hinges to make a mechanism.
The slab that spans both ways
A panel supported on four sides sends its load in two directions at once, and the share is decided by a fourth power — so a panel a third longer than it is wide has already stopped being a two-way slab in any useful sense. What it does at collapse is a different calculation with a different answer.
Named alongside it
The objects these essays reach for when they reach for this one.
Collapse mechanismPlastic hingeLoad pathLower boundMoment redistributionPlastic momentSpan scalingTributary areaTwo way spanningYield line