¶ Barrel
Index Entry
A barrel represents an advanced phase of the Roman Arch or principle of stability accomplished by simple curvature. The parallel barrel staves constitute a ring held together in compression by encompassing tension bands. Thus compression, which tends to curve, is favored in that tendency until the curving line of compression closes itself to thrust against itself. The tension line, which tends to pull true, forms itself in a finite closure of short true chords-- because tension members may be flexed while they are in tension without tendency to failure.
The tension ends are united to pull against one another. Thus we have closed circuits of tension arch-bundling compression in dynamic stability. Tension lines may also be flexed while under load, without tendency to failure, as a compound corollary of the principle to pull true and the ability to tolerate bending while tensed. Pressures exerted either outside or inside of the barrel result in outward thrust of the staves against the tension members. Thus, the latter absorb the working or random loads. …
