Collapse load — where it appears
Named by 4 essays across 4 fields — each of them below, with the objects they name alongside it.
The point the mechanism turns about
A collapsing frame is a chain of rigid pieces, and every piece is rotating about some point. Find those points and the whole collapse load reads off two ratios of lengths, with no trigonometry anywhere — and for a pitched roof the point in question is well above the top of the drawing.
The smallest of six failures
Everything else in this collection that fails does so in one way at a time. A dowel through timber does not — the wood can crush while the steel stays straight, or one plastic hinge can form in it, or two — and the capacity is the smallest of the six, which is the kinematic theorem of plasticity applied to a joint rather than to a frame.
The pressure that needs no direction
Every buckling problem in this collection has had a load with a direction — a column pushed along its axis, a plate along its edge, an arch by what is on it. A buried pipe has none. The pressure is the same everywhere, it stays normal to the wall as the wall moves, and it does work on any change of shape that reduces the area inside.
The steel that is stronger in a millisecond
Every strength quoted anywhere in this collection was measured at about a ten-thousandth of a strain per second, because that is what a testing machine does, and nothing on a drawing says so. Load the same steel a million times faster and its yield stress rises by a third.
Named alongside it
The objects these essays reach for when they reach for this one.
Free bodyPlastic hingeBound theoremsDuctilityEquilibriumAnisotropyBearingBlastBuckling modeCapacity designConnection designCowper symonds