Structural Engineering & Statics
where the load goes
Generator

The laced-column generator

Rendered here at the parameters it defaults to, with every essay that calls it — which is the same list as the blast radius of changing it.
A built-up column has a second way to bendA 12 m column of two chords 300 mm apart, joined by double lacing. On the left it buckles the way a solid column does, by bending; on the right the chords stay straight and the lattice racks, which a solid column cannot do at all. Neither happens alone, and the two flexibilities add rather than the two stiffnesses — so the critical load is 1287 kN against an Euler load of 1341 kN, which is 96% of it, and the column behaves as though its slenderness were 80 rather than 79.bending, as a solid column doesP_E = 1341 kNracking, which a solid column cannotS_v = 31500 kN1/P꜀ᵣ = 1/P_E + 1/S_v → 1287 kNthe smaller of the two governs, and here it is the bending

A built-up column has a second way to bend. A 12 m column of two chords 300 mm apart, joined by double lacing. On the left it buckles the way a solid column does, by bending; on the right the chords stay straight and the lattice racks, which a solid column cannot do at all. Neither happens alone, and the two flexibilities add rather than the two stiffnesses — so the critical load is 1287 kN against an Euler load of 1341 kN, which is 96% of it, and the column behaves as though its slenderness were 80 rather than 79.

2 essays call laced-column. The drawing above is what it returns with no arguments at all; every call below passes it something, because a placement that passes nothing draws whichever member of the family the generator happens to default to rather than the one its essay argues about.

Where it is called

Changing this generator changes every one of these figures.

the same, laid flatr = 4.3 mmλ = 9247 kNsquarer = 15.8 mmλ = 25397 kNtall rectangler = 57.7 mmλ = 691295 kNI-sectionr = 90.0 mmλ = 443146 kNthe dashed pair is ±r about the centroidthe bar is the Euler load at 4 m, to scale Sections and stress

The one length a section takes into a column

A section has an area, a second moment, two section moduli, a shear centre and a torsion constant. A column has heard of exactly one of them, and it is none of those — it is the length √(I/A), which is where the whole area would have to sit to give the section the stiffness it has.

 bending, as a solid column doesP_E = 1341 kNracking, which a solid column cannotS_v = 31500 kN1/P꜀ᵣ = 1/P_E + 1/S_v → 1287 kNthe smaller of the two governs, and here it is the bending Stability

The column made of two columns

A solid column buckles when its bending stiffness runs out. A laced one has a second way to go — the lattice shears, the chords stay straight — and the two flexibilities add rather than the two stiffnesses. A battened column reaches 23% of its own Euler load and behaves as though its slenderness were twice what it is.

The library, page 2 of 6 — where laced-column sits