Structural Engineering & Statics
where the load goes
Concept

Sway frame — where it appears

2 essays name this object, across one field. What follows is each of them, and the objects they name alongside it.
K = 0.5both ends fixedK = 0.7one fixed, one pinnedK = 1both ends pinnedK = 2fixed at the base, free at the topsame column, same section, four ways of holding the endsthe load at which each buckles goes as 1 ÷ K² — a factor of sixteen across this row

The ends decide the length that matters

Four columns of identical height and section, buckling at loads sixteen times apart. Nothing differs but what is holding the two ends.

stability · effective length the storey that cannot driftk = 0.774N꜀ᵣ = 16.46 EI/L²the storey that cank = 1.317N꜀ᵣ = 5.69 EI/L²the same column, 2.9 times the load — the restraint is the whole of the difference

Held, and not held

One horizontal restraint at the head of a storey, carrying no vertical load whatever, moves the critical load of the columns beneath it by a factor of 2.89. Effective length is a property of the frame, not of the member.

stability · sway stability

Named alongside it

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

BracingBuckled mode shapeEffective lengthCritical loadEigenvalueEnd restraintSecond order effectsSlendernessStiffness

All concepts