Structural Engineering & Statics
where the load goes
Concept

Buckling mode — where it appears

The shape a structure takes as it buckles, which falls out of the same eigenvalue problem as the critical load. Restraint can change it as well as raise the load: a ring in soil buckles into four lobes rather than two, because a long lobe has more soil to push out of the way.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

020040060080010000100200300400brace stiffness (kN/m)critical moment (kNm)compression flangeshear centretension flange447 kN/m is enougha rigid brace buys 3.12, not two

The brace on the wrong flange

A brace on a column has one property that matters, and it is stiffness. A brace on a beam has two, and the second decides whether the first is worth anything: put the identical restraint on the tension flange and it does not reach the answer at any stiffness whatever.

stability · beam bracing n = 20.138n = 30.367n = 40.689n = 51.102critical pressure in N/mm² · lowest is n = 2

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.

stability · ring buckling

Named alongside it

The objects these essays reach for when they reach for this one.

BracingCollapse loadCompression flangeCritical loadCritical momentEffective lengthElastic foundationEnergy methodEquilibriumExternal pressureFree bodyIdeal brace stiffness

All concepts