Building with Earth: Design and Technology of a Sustainable Architecture

119 Designs of building elements

nents. The steeper the forces are conducted

into the foundation, the smaller are the

horizontal forces, and the easier the forma-

tion 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 incli-

nation of the resulting load is reduced by

means of superimposed loads. A second

simple solution, shown in B, consists of but-

tresses. In this case, to prevent excessive

bending stress, spacings between buttress-

es should not be too large. A structurally

superior variation is shown in C, with but-

tresses connected by arches. Solution D

shows the transfer of the resultant horizon-

tal thrust to tensile structural elements in the

floor (reinforced concrete plates, for exam-

ple), which neutralise the thrust so that only

vertical forces are transferred to the founda-

tion. 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.

14.34

14.37 14.38

14.35 14.36