Structural Engineering & Statics
where the load goes
Concept

Plate slenderness — where it appears

A panel's width divided by its thickness, which decides whether it reaches the material's yield stress before it ripples.

Named by 3 essays across 3 fields — each of them below, with the objects they name alongside it.

flange outstandk = 0.4318.6 at 23515.2 at 35513.3 at 460quoted: 14ε1.33× the quoted limit, at every gradeweb, in bendingk = 456.8 at 23546.2 at 35540.6 at 460quoted: 42ε1.35× the quoted limit, at every grade0102030405060width ÷ thickness

The section that cannot reach its own strength

A section classification looks like a table of arbitrary numbers. Set a plate's buckling stress equal to the yield stress and the numbers fall out of a formula written three phases ago — larger than the quoted ones by a constant factor, at every grade.

materials · section classification stiffeners at 1000 mmthe band at 22.5°the truss it has becomestiffener in compression,web in tensionbuckles at 383 kN · carries 696 kN · a stocky web would reach 953 kNσ in the band 252 N/mm² over 541 mm

The panel that carries more after it has failed

Everywhere else in this field a critical load is where the argument ends. A thin web is the exception — it buckles visibly, in waves anybody can see, and then goes on to carry nearly twice as much again by turning itself into a truss nobody drew.

stability · tension field flat: I = 6750 mm⁴folded: I = 67.50×10⁶ mm⁴300gain 10000× = (100)²limited by buckling of the leg: the leg goes at 27 N/mm²

Folded until it spans

A flat sheet has a second moment of area of B·t³/12 and will not span anything. Folded, the same material has B·t·h²/12, and the gain is exactly the fold depth over the thickness, squared — a ratio with no material in it and no width in it.

structures · folded plate

Named alongside it

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

Local bucklingEfficiencyPlate bucklingStiffnessCritical loadDuctilityEffective widthForm findingImperfectionLoad pathMoment curvatureOne way spanning

All concepts