Structural Engineering & Statics
where the load goes
Concept

Buckling — where it appears

3 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
0.511.52050100150200250300depth of the truss2501671251007150the same moment, resisted by a longer lever arm

Depth is the cheapest strength there is

Doubling the depth of a truss halves its chord forces without adding a gram of material to the chords. Nothing else in structural design is that cheap, and almost every structure has already spent it.

structures · span to depth 00.1%0.2%0.3%0.4%0.5%0.6%050100150200250300350strainstress, N/mm²mild steelaluminiumconcretetimber

The one number a stronger steel does not change

Geometry beats material almost everywhere on this site. Stiffness is the exception in the other direction — it cannot be bought at all, because every steel ever made has the same elastic modulus.

materials · elastic modulus 20040060080000.20.40.60.81temperature, °Cfraction of the cold valuestrength runs out at 558°Cstiffness at 500°Cyield stresselastic modulusworking at 60% of cold capacity

The hour that is really a temperature

A fire rating is quoted in minutes and there is no time in the physics anywhere. What decides is a temperature, and the stiffness reaches its limit sixty degrees before the strength does — so the way a member fails can change while it is burning.

materials · fire

Named alongside it

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

Elastic modulusProof stressChord forceCreepCritical temperatureEfficiencyFireLever armLoad ratioMaterial selectionRetention factorSecond moment of area

All concepts