Civil Engineering Reference
In-Depth Information
is evident that these walls are load bearing walls,
sui generis
, since the load they
bear is a thrust, a horizontal pressure. h is, of course, inl uences both their design
and construction, since such pressure increases rapidly with the depth below the
surface of the retained mass (T. Reynolds and L.E. Kent, Chap. XVI, pp. 31-64).
Very material in this connection is the type of masonry bonding employed better
to resist lateral deplacement. h us reference to retaining walls is inevitable when
discussing polygonal and Lesbian masonry. However, again it must be stated
that these considerations are highly specialised ones, they relate to engineering
works not to building construction and will not be treated substantively in this study.
Also it may be noted that there is reason to mention these matters at the begin-
ning of load bearing construction because of the historical instance. In the earli-
est building of pre-pottery Neolithic times (the Round House) solid stone walls
were not used to support the roof. h ey were used as barrier or retaining walls to
enclose the sunken l oor emplacement. Rooi ng was rigged up on a light wooden
framing of some sort (Vol. 1 pp. 18, 19).
Stone in its characteristic use as a load bearing material raises the issue of solid-
ity, stability of construction—i.e. rigidity, the resistance to deformation. h ere
are several measures in building construction which severally or in combination
augment the rigidity of stone walling (“stif en it”):
h e
rigidity
of load
bearing
stone
construc-
tion
(a) Bonding
(b) Fixing
(c) Reinforcing
(a)
Bonding
Bonding is the process of setting masonry units together in such a way that the
pattern militates against the deformation, damage or collapse of any part of the
structure. h e principle is that the disposition of the units distributes evenly
throughout the structure loads applied to it unevenly, i.e. concentrated at certain
points. However the common understanding of bonding that it is of general ei -
cacity in this connection is errant. Bonds familiar in traditional masonry which
presume setting units in uniform continuous courses are conceived to resist
normal forces transmitted vertically downwards through the masonry, i.e. those
induced by bearing the load of upper l oors and rooi ng. If such a wall is subject
to horizontal forces (e.g. those induced by human battery, or by earthquake) then
the continuous joints running horizontally through the masonry at the beds of
each course constitute a weakness. h e actuality of this is made familiar in i eld
archaelogy, where quite ot en the articulated remains of walls can be seen which
have toppled over en masse at a certain course of masonry or indeed have been
displaced horizontally at a certain bed joint. h e type of masonry which best resists
