Civil engineering handbooks, available at many public libraries, provide
guidance on permissible bending loads on structural members of many
shapes.
Those same handbooks define slender columns and provide guidance on
permissible column loading to prevent buckling failures.
Analysis of permissible loads on soil, particular in regard to sideways
loading, are complex. In many cases, we conservatively assume that soil
is a viscous liquid and will not support sideways loading, and we
engineer a structure, as many bases for small self supporting towers are
engineered, to resist overturning based on the shape and size of the
footprint and the combined weight of the base, tower, and elements
mounted on the tower and on the facts that the base is below ground so
that it is partly floated by the density of the earth it displaces and
that soil pressure at the bottom of the base will tend to prevent
permanent displacement of the soil under the base even if it is
temporarily displaced by wind gusts. This simplification results in an
excessively strong installation, and the added cost for typical ham
towers is less than the cost of soil testing, analysis, and engineering
to more precisely specify the installation.
It is common to similarly anchor guys to a massively overengineered
deadman - heavy, buried deep, and of ample crossection perpendicular to
the load.
With suitable soil testing, analysis, and engineering, you may specify a
minimal mount for elevated guys. It may be less costly to overdo them.
Consider: a steel fence post stands fairly well for many years. It is
seldom subjected to sideways loads the tilt it. The soil may be
temporarily displaced, but it returns to support the post.
f you wish to pull a post out of the ground, you may, with alternating
force at the top of the post, move soil sideways until the ground
releases the post for easy removal. Loading moves the soil sideways and
the application of alternating loads in a short time prevents the soil,
which moved as if it was liquid, from flowing back before application of
the next load. Each succeeding load displaces the soil a bit more,
resulting in a hole around the post.
I'm not saying what won't survive, but I hope to point out some of the
considerations and reasons for installing towers in accordance with
engineered specifications if you wish them to stay up.
73 de WOØW
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