Structural Engineering & Statics
where the load goes
Generator

The thermal-restraint 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.
It moves, or it pushes. Never both, and never neitherA 30 m steel member 30 °C warmer than it was built, in three conditions. Free, it grows 10.8 mm and carries nothing. Held, it moves nothing and carries 75.6 MPa — which is E·α·ΔT and contains neither the length nor the area of the member, so the identical stress arises in a two-metre strut. Held by a spring it does some of each: 3.2 mm of movement and 53.2 MPa, and the split is decided by the spring rather than by the member.free at one end10.8 mmno stressheld at both ends75.6 MPaheld by a spring of 100 kN/mm53.2 MPaE·α·ΔT = 210000 × 12×10⁻⁶ × 30 = 75.6 MPa, at every length

It moves, or it pushes. Never both, and never neither. A 30 m steel member 30 °C warmer than it was built, in three conditions. Free, it grows 10.8 mm and carries nothing. Held, it moves nothing and carries 75.6 MPa — which is E·α·ΔT and contains neither the length nor the area of the member, so the identical stress arises in a two-metre strut. Held by a spring it does some of each: 3.2 mm of movement and 53.2 MPa, and the split is decided by the spring rather than by the member.

1 essay calls thermal-restraint. 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.

free at one end10.8 mmno stressheld at both ends75.6 MPaheld by a spring of 100 kN/mm53.2 MPaE·α·ΔT = 210000 × 12×10⁻⁶ × 30 = 75.6 MPa, at every length Deflection

The movement nobody applied

A temperature change is the only load in this collection that a structure can decline. Let it move and it produces a movement with no stress; hold it and it produces a stress with no movement — and that stress contains no length, no area and no second moment, so a bracket and a bridge girder carry exactly the same one.

The library, page 4 of 5 — where thermal-restraint sits