Structural Engineering & Statics
where the load goes
Generator

The bearing-wedge 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 bearing capacity is a mechanism, and here it is. Prandtl's collapse mechanism under a 2.5 m footing in a soil of 30° friction. A rigid wedge is driven down with the footing at 60° to the horizontal; a fan of radial shear turns the stress through exactly ninety degrees on a logarithmic spiral whose growth rate is tanφ; and a passive wedge at 30° has to be pushed up and out of the way. Nothing here is empirical — every angle is a function of φ alone — and the mechanism reaches 12.0 m from the centre, which is 9.6 times the footing's half width. That is why two footings closer together than about four widths do not have separate bearing capacities.

A bearing capacity is a mechanism, and here it is. Prandtl's collapse mechanism under a 2.5 m footing in a soil of 30° friction. A rigid wedge is driven down with the footing at 60° to the horizontal; a fan of radial shear turns the stress through exactly ninety degrees on a logarithmic spiral whose growth rate is tanφ; and a passive wedge at 30° has to be pushed up and out of the way. Nothing here is empirical — every angle is a function of φ alone — and the mechanism reaches 12.0 m from the centre, which is 9.6 times the footing's half width. That is why two footings closer together than about four widths do not have separate bearing capacities.

1 essay calls bearing-wedge. 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.

A bearing capacity is a mechanism, and here it is. Prandtl's collapse mechanism under a 3.0 m footing in a soil of 32° friction. A rigid wedge is driven down with the footing at 61° to the horizontal; a fan of radial shear turns the stress through exactly ninety degrees on a logarithmic spiral whose growth rate is tanφ; and a passive wedge at 29° has to be pushed up and out of the way. Nothing here is empirical — every angle is a function of φ alone — and the mechanism reaches 15.9 m from the centre, which is 10.6 times the footing's half width. That is why two footings closer together than about four widths do not have separate bearing capacities. Equilibrium

The ground is a mechanism

Bearing capacity is met as a formula with three terms and a table of coefficients, and that presentation hides what it is. Underneath is a plastic collapse mechanism — a rigid wedge, a fan of radial shear on a logarithmic spiral, and a passive wedge that has to be pushed up and out of the way — and every coefficient in the table is a property of that one drawing.

The library, page 1 of 7 — where bearing-wedge sits