Structural Engineering & Statics
where the load goes
Concept

Beam on springs — where it appears

A beam whose supports deflect under the reactions they carry, so that the sharing between them depends on relative stiffness rather than on tributary area. A stayed deck, a floor plate distributing wind to walls, and a beam sitting on other beams are all this one problem.

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

1017201710the frame, before it settledsoft ground heresettlement in millimetres, mean 15worst angular distortion 1 in 415 between footings 0 and 1limit 1 in 500 — fails

The settlement that matters is the difference

A building that goes down half a metre uniformly is undamaged and needs a new front step. One that goes down a twentieth as far, unevenly, has cracked. The superstructure can even the difference out — and the only way it can do so is by carrying the difference itself, as a force.

deflection · differential settlement tower 70 m200 mdeck compression at the tower 61905 kNstay force 3427 to 10090 kNlongest stay has lost 1.2 per cent of its modulus to sag

The cable that is a spring

A suspension bridge's cable is a funicular — it takes the shape the load gives it, and the deck's job is to make the load one that shape is right for. A stayed deck is not that at all. Its cables are straight, each reaches the deck at one point, and every one of them behaves as an inclined spring.

structures · cable stayed

Named alongside it

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

Load pathAngular distortionBucklingCable stayedConstruction sequenceDamage criterionDeck compressionDifferential settlementEquilibriumErnst modulusFoundationFree body

All concepts