Structural Engineering & Statics
where the load goes
Concept

Stress — where it appears

Force per unit area at a point, which is a property of the material's state rather than of the load path. It and the internal force are different quantities that usually travel together — a hoop force is the case where they come apart, since it contains no thickness and the stress does.

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

NN2R = 0.60 m — the projected widthp = 1 MPap · 2R = 2N ⇒ N = pR = 300 kN/mno thickness in it, no second moment, no length

The force that is only a radius

Every internal force in this collection arrives with a lever arm attached. A hoop force does not. Cut a cylinder along a diameter and the free body settles it in one line — pressure times radius, with no thickness, no second moment and no length in it — which is why a tank wall is thin and why its worst hoop force is not at the bottom.

internal-forces · hoop tension the brace force30°b_eff = 367 mm90 mm4.08× the width anything is actually attached togoverns on the Whitmore section buckles, at 721 kN

The width nobody drew

Every other member in this collection arrives with a cross-section. A gusset plate does not — it is a piece of steel with a brace bolted to it somewhere in the middle, and no geometry says how much of it is working. The profession's answer is a thirty-degree spread from a 1952 master's thesis, it invents three quarters of the area being checked, and the check it was written for is not the one that governs.

connections · gusset

Named alongside it

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

BearingBending momentBlock shearBoundary layerBraceConnection designCrack controlDispersionDomeEffective lengthEquilibriumFree body

All concepts