Limit point — where it appears
Named by 2 essays across 2 fields — each of them below, with the objects they name alongside it.
The roof that jumps
Every stability failure in this collection so far has been a bifurcation — a straight thing discovering it can be bent. A shallow frame does something else entirely. It stays perfectly symmetric, deforms steadily, and at some point the load it can carry starts to fall while it is still moving in the direction it was pushed.
The force nobody put in the model
A slab strip whose ends cannot move apart is not the strip in the yield-line calculation. Deflecting shortens the chord between its ends, the ends do not come in, and the strip is forced into an arch — worth four times the load it was designed for, at a movement nobody would see.
Named alongside it
The objects these essays reach for when they reach for this one.
Alternative load pathBifurcationBucklingCatenaryCollapse mechanismCompatibilityEquilibrium pathGeometric nonlinearityHorizontal thrustMembrane actionNo tension materialProgressive collapse