Structural Engineering & Statics
where the load goes
Concept

Anchorage — where it appears

The provision that stops a force pulling out of the material it is delivered into, whether a bar's embedment, a hold-down bolt or a tension pile. Its size is the force divided by whatever stress the surrounding material can pass, and it is often the largest thing a small pressure produces.

Named by 3 essays across 2 fields — each of them below, with the objects they name alongside it.

36shearthe bars clamp, and do not carryasperity slope 54° · tan = 1.40clamping stress 2.50 N/mm² · resistance 3.50 N/mm²sliding without separating is not available to a rough crack

Shear across a crack that is already there

Every shear calculation in this collection starts from an uncracked solid — a principal stress, a shear flow, a diagonal tension. This one starts after the crack, on a plane with no tensile strength at all, and the coefficient it uses is not a coefficient of friction. It is the slope of the roughness.

internal-forces · shear friction 137 kN806 mm = 40φ00.20.40.60.8100.20.40.60.81along the embedded length÷ its own peakelastic forceuniform forceelastic bond stressuniform bond

The force that arrives along a length

A bolt takes its force at a hole and a weld along a line. A reinforcing bar has no such place — it is a smooth cylinder in a hole of its own shape, and the only thing stopping it sliding out is a stress smeared over its surface. So the force in it is not a number, it is a function of position.

internal-forces · bond 18 kN/m18 kN/mN = 9.3 kN/m1190 Pa121 mm of water60 mtotal uplift 3365 kNworst membrane force when the snow melts

Held up by the air inside

A membrane has no bending stiffness at all, so the only thing that can hold it in tension is a pressure difference. The pressure needed to hold up a roof is smaller than the pressure a closed door makes — and the same pressure arrives at the foundation as hundreds of tonnes of uplift.

structures · pneumatic structure

Named alongside it

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

EquilibriumFree bodyAggregate interlockBondCable netClamping forceConstruction jointCorbelCrackCurvatureDecay lengthDevelopment length

All concepts