Structural Engineering & Statics
where the load goes
Concept

Interface — where it appears

A plane between two parts of a member across which force has to pass. What crosses it is a shear flow, largest where the shear is largest, and whatever provides for it is the whole of the composite action.

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

051015202530354000.20.40.60.81αLdegree of interaction96% at αL = 15.8one beamtwo beamsEI∞/EI₀ = 3.24 · the whole range is a factor of 3.24 in deflection

Half the studs, and most of the beam

Bonding two layers together quadruples the stiffness of the pair. A real connection is a row of studs that deform, so the layers slide a little and the beam sits between the two answers — but not halfway between, and the number that decides where is a single dimensionless group.

internal-forces · partial interaction facescore — 25 N/mm² in sheard = 61 mm between the face centroids41 N/mm²41 N/mm²the core carries none of itbending stressD = 91.35 × 10⁹ N·mm² · 98.8% of it is the separation termwrinkling at 236 N/mm², which contains no length at all

Two skins and the space between them

A sandwich panel is a section made of a material that carries the bending and a material that carries none of it. The parallel-axis term is not a correction here — it is 98.8 per cent of the second moment — and the shear deflection is not a correction either.

sections · sandwich section

Named alongside it

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

Composite actionNeutral axisParallel axis theoremSecond moment of areaServiceabilityStiffnessCompatibilityCoreDeflectionDuctilityEquilibriumFace

All concepts