Concept

Camber — where it appears

A curvature built into a member so that it takes the intended shape under a chosen load rather than when it is unloaded. It is fabricated against one stage of a sequence, so it is right on one day and wrong on every other, and choosing the day is a specification rather than a calculation.

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

The section that changed while it was being loaded

A stress is computed from a moment and a section modulus. When part of the moment arrived while the section was a different shape, there is no single section modulus to divide by — the stresses add and the properties do not, and two identical finished beams can differ by half again in stress with nothing on the drawing to say which is which.

sections · staged section

The curvature nobody applied

Concrete shrinks as it dries, by about half a millimetre in every metre. In a symmetrically reinforced member that is a shortening and nothing else. In a member with more steel in one face than the other — which is every beam and every slab — the steel holds one side back and the section bends, with no load on it at all.

deflection · shrinkage curvature

Named alongside it

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

Creep Differential shortening Modular ratio Self equilibrating Compatibility Composite action Construction sequence Cracked section Curvature Deflection Locked in stress Partial interaction

All concepts