Building with earth - Gernot MINKE (1)

14.35 14.36
14.34
nents. The steeper the forces are conducted
into the foundation, the smaller are the
horizontal forces, and the easier the formation
of foundation. A rule of thumb is that
the forces resulting from vault thrust and
wall loads must fall within the middle third
of the pedestal and foundation bases. This
means that eccentricity should be no more
than 1 /6 of the breadth (14.38).
Since this consideration can mean a very
large and, hence expensive foundation, it
may prove expedient to plan for additional
structural measures, such as those shown
in 14.39. In solution A, for example, the inclination
of the resulting load is reduced by
means of superimposed loads. A second
simple solution, shown in B, consists of buttresses.
In this case, to prevent excessive
bending stress, spacings between buttresses
should not be too large. A structurally
superior variation is shown in C, with buttresses
connected by arches. Solution D
shows the transfer of the resultant horizontal
thrust to tensile structural elements in the
floor (reinforced concrete plates, for example),
which neutralise the thrust so that only
vertical forces are transferred to the foundation.
Solution E shows single tensile ties
which act in the same way. They are placed
above the walls supporting the vault. In this
case, ring or peripheral beams have to be
provided, which can take the bending forces
that occur between the tie ends. Solutions F
and G show two different ways of diverting
the thrust of the central dome to low lateral
vaults.
14.37 14.38
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Designs of building elements