Structural Engineering & Statics
where the load goes
Concept

Temporary works — where it appears

The bracing, propping and falsework that hold a structure up before its own load path is complete, and which are structures in their own right. They are designed to the same standards as the permanent structure and are removed before anybody sees them, which is why their failures are so much more common than the finished structure's.

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

0.020.1011025000.20.40.60.8floor-plate stiffness ÷ wall stiffnessshare of the storey forcethe middle wallan end walltributary arearigid plate← soft plate

The floor is a beam lying down

A floor plate spans horizontally between the walls that resist a lateral load, carries a distributed inertia load, and has chords, a web and a span-to-depth ratio like any other beam. Its stiffness decides whether the walls share the load by their stiffness or by the area of floor nearest them — and the familiar tributary answer turns out to be neither limit.

structures · diaphragm 02040608000.20.40.60.811.21.41.6brace stiffness (units of EI/L³)effective length factor k23.2 EI/L³ = 1.41 N꜀ᵣ/L0.77 — held1.32 — freepast the threshold the frame buckles in a mode the brace does not hold

The most dangerous day is before it is finished

A structure is analysed once, complete, with every restraint present. It spends weeks in states nobody drew — a beam landed with no deck on it holds 17% of the moment its section is worth, a frame not yet braced buckles at a third of the load it will, and a bolt not yet tightened is a pin where the analysis assumed a fixity.

stability · erection stability

Named alongside it

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

Erection stabilityAccidental eccentricityBracingCentre of rigidityChord forceCollectorConstruction sequenceDeep beamDiaphragmEffective lengthIn plane stiffnessJoint stiffness

All concepts