Concept

Cold formed — where it appears

A section made by bending thin sheet rather than by rolling hot, which makes very thin plates and very efficient shapes available. Its plates buckle locally well before the material yields, so its design is about effective sections and mode interaction rather than about strength.

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

What is left after it ripples

A thin plate that buckles locally has not failed. It has stopped taking load in its middle and gone on taking it near its edges, so the member is now made of a different section from the one that was drawn — and the new one has its centroid somewhere else, which turns a concentric load into an eccentric one.

sections · effective cross section

Two ways of buckling at once

A thin-walled column can bow as a whole or ripple in its plates, and each has its own critical load. The received advice is that the worst arrangement is the one where the two are equal. The arithmetic says the opposite — at coincidence the interaction costs two per cent, and the expensive region is where the plates go first.

stability · mode interaction

Named alongside it

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

Effective width Local buckling Post buckling Section classification Slenderness Squash load Centroid Critical load Direct strength method Eccentricity Eigenvalue Global buckling

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