The Ohio Democrat. (Logan, O. [Ohio]) 1886-1906, 1894-06-23
LAYING THE FOUNDATION.
How Architects Have Overcome Ono o.
ChicagO'S Natural Obstacles.

How Architects Have Overcome Ono OF
ChicagO's Natural Obstacles.
Foundations for large Chicago build
ings are constructed in peculiar man.
ner owing to the nature of the material
underlying the city. The site was
originally wild rice swamp. which
has been gradually filed in until the
streets are now at an average elevation
of about IA feet above the water level
OF the lake. All large cities have an
artificial top stratum. but Chicago is
unfortunate in having below the arti-
fetal filling and the thin natural ton
layer of earth jclly-likc mass of clay
OF very variable depth. The sustaining
power of this clay is only from $500 to
1000 pounds d square foot. and on this
account it has been customary until re-
Gently for the architects of high build
ings to support them by spreading
floors of concrete and steel beams under
each wall and column. Even with
such web-footed foundations, build.
ings sometimes settled unevenly. pro
ducing cracks and endangering the
lives of their occupants. the great
Board of Trade building being perhaps
the most noteworthy instance OF this.
Recently some of the largest buildings
have been provided with deep pile
foundations, reaching cntisely through
the jelly stratum into the firm, hard
clay below. The Stock Exchange
building now going up is an
example. 1t is l1O feet. inches
wide and $50 feet, Q inches long,
measured on the building line. all
though the foundations are extended
beyond these limits in order to support
the walls. The piles used were 80 feet
ong and driven in clusters about B feet
lpart. A steam hammer was employed
to drive them. which weighed S,4OJ
pounds and was provided with II 4, 400
pound tup, or striking part, having -
stroke of 3i4 feet. With this hammer
1aS piles were driven in one month.
,ach pile being so spaced as to support
tweight of at least thirty tons. Tim,
Oers IL inches square We're laid across
the foundation on top of the piles and
covered with grillage of similar tim.
oers running at right angles to the
first set. On these IL concrete and steel
beam base was made for each column
n wall. the total amount of steel re-
CURED being about l25 tons. On one
.,dc the foundations joined those of the
Herald" building. and MS piles could
not he driven here there walls Carried
by walls from 3 to q feet 4 inches in
diameter, filled with concrete. These
We're excavated down TO TIL, hard clay
sub bstratum by means OF circular
sheathing of oak. stav,s he'd in p,ac:
by steel rings. When tie concret,
hardened these W lis necime equiva
lent to piers such as upport bragas
the only d ffer.nce ID Inc the T. smaller
diaineter. n prop ,rtion to thr l. leogth
The co;t of esnc.i foundations is Stat.
to b. abant the same a> that or til
wide-sprsading concrete and steel typ.
which has been SO long in use, wnilt
they take up but very little room above
the floor level of the basement, in
which respect they differ again from
the spread foundation. Their mse /.
gradually increasing and among ths
receni buildings built on them are the
new Illinois Central station the Art
Institute, aad the Medina Temple.
Oh .cago kecord.