Structural Engineering & Statics
where the load goes
Concept

Cable — where it appears

A member that carries load in tension only, taking the funicular shape of whatever it is holding. Its stiffness comes from its geometry rather than from its material, so a slack cable is not a soft spring but very nearly no spring at all.

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

259 kN95299 kN83221 kN112wind 3 N/mmtop moves 100 mmleewardwindwardaxial load from the guys 801 kN · deflection exaggerated 0.5×

Held by something that goes soft

A guy is a cable, so it has no stiffness of its own — what resists a mast's movement is the guy's geometry changing, and how much of that there is depends on the tension already in it. Wind pushes the mast towards the leeward guy, which is the one losing tension.

structures · guyed mast 0.511.520500100015002000depth of the truss1500857600429316the same moment, resisted by a longer lever arm

The same span, four ways

A beam, a truss, an arch and a cable can all cross the same gap under the same load, and the choice between them is usually described as a matter of judgement or of taste. It is neither. Each carries the load by a different mechanism, each mechanism has a different exponent, and an exponent decides the ordering at every span rather than at some spans.

structures · form selection

Named alongside it

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

AnchorArchBeam columnBucklingElastic supportFunicularGeometric stiffnessGuyed mastHorizontal thrustLever armLoad pathMaterial index

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