Structural Engineering & Statics
where the load goes
Concept

Tolerance — where it appears

The permitted departure of a manufactured dimension from its nominal value. In a statically indeterminate assembly it is not a cosmetic quantity: a millimetre of difference between two nominally identical members redistributes force between them in proportion to their stiffness.

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

012345678-0.03-0.02-0.0100.010.020.03along the span (m)deflection, each scaled to the same mid-span drop3.20 · a uniform load3.00 · a load at mid-span2.99 · a triangular load3.60 · a load on half the spanθ = C · δ/L, and the same δ gives 1.21× the rotation across these

The angle nobody limits

Every serviceability rule in this collection limits a displacement. What a bearing, a joint and a cladding gap actually have to accommodate is an angle — and the angle is locked to the displacement by a coefficient that contains no material, no section and no span.

deflection · end rotation hook100 kN57.7 kN57.7 kN60°57.7 kN of compression, in the load2040608000.511.52sling angle (degrees)leg force ÷ load30°

The angle that doubles the force

A crane hook takes the weight and nothing else. What holds the load is a set of legs running down to it at an angle, and each leg is a two-force member — so at thirty degrees from the horizontal each of two legs carries the entire load, and the difference goes into the thing being lifted as compression.

equilibrium · rigging

Named alongside it

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

StiffnessBearingBucklingCentre of gravityCladdingCompatibilityCurvatureDeflectionEnd rotationEquilibriumErectionExpansion joint

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