Los Angeles herald., 1905-12-24

fornla Chapter OF the American III
stitute of Architects, read an inter-
estine paper on the use Of reinforced
concrete in large buildings This ma
terial is used in the construction of the
Hill street annex OF the Laugnlin
building, in the DR.. Hayward buildlng'
corner of South Spring and sixth
streets. and i'm the Citizens National
bank building corner of Third ana
Main streets.
Durability Of Concrete
Following are extracts from the AL
bright paper
Concrete is commonly understood TO
be a conglomerate Of broken stone or
gravel, sand and cement, thoroughly
mixed with water and tamped in place.
1t was the material most extensively
used by the Romans and, in strength
and durability, no mass, however hard
the stone or large the blocks, equals
the walls of concrete which they built
and which can only be destroyed by a
laborious process like that of quarry
ing stone from it's native bed.
The Pantheon in Rome, about 2OOO
years old, is covered by a dome 1926
feet in diameter, cast in concrete, be-
ing one solid mass, covering the build
ing like a shell.
Reinforced concrete is concrete in
which has been imbedded steel bars
OF the proper form and size and in the
proper position for the purpose of re-
sisting tensile stresses,
In 1S49 Lambol de Minoval built
boat of concrete in which he imbedded
steel netting. In 1855 he exhibited this
boat at the worlds fair at Paris and
1t was then credited as being the first
reinforced concrete structure.
In 1867, Monier a French gardener
a nrnriD1oG in eft rI1pt-
ing flower boxes, small water tanks
and the like, and to him was issued
the first patents on reinforced concrete
construction. Soon after this its use
was extended to the construction of
floor slabs, pipes, etc.
Hennebique is credited with being
the first to adopt the principle of REIN
forced concrete to columns, beams, etc.
Companies operating under his patents
have erected buildings which have cost
upwards of $50 100000. Numerous
companies have been formed for the
purpose of constructing buildings of re-
inforced concrete and they have erect
ed in all parts of the civilized world.
buildings which, in the aggregate, have
cost many millions of dollars.
Use Is General
Although the practical advantages Of
reinforced concrete were demonstrated
long before theoretical analysis of its
properties were entered into, there is
still much hesitacy over its use, due,
no doubt, to the want of an understand
ing of its true properties However,
tests, experiments and researches have
been made as years have gone by, until
today formulas have been established
whereby the architect and engineer can
calculate to nicely the results that
will be attained under a given propo-
sition.
The use of reinforced concrete has
become so general and its importance |
has grown to such an extent that no |
architect or civil engineer can afford to
be without a thorough knowledge Of |
its properties and applications: for the |
time is fast coming when this type of
construction will be more extensively |
used than all other types combined. |
and the architect or engineer who is !
not prepared to undertake the work |
will be in want of something to do. |
There is hardly anyone who will not
concede that both concrete and steel
are uneXcelled building materials, and |
o proper combination of the two ma
terials which make reinforced concrete, |
must necessarily make it all that canI
be desired.
The best authorities estimate that |
the tensile strength of the strongest |
concrete is only about one-tenth of it's |
resistance to compression: therefore, |
the combination with concrete of a |
material which shall possess the requi- |
site tensile strength, Is the most seri- |
Gus problem i'm reinforced concrete. II |
IS essential that the elasticity of the |
steel be so reduced that the steel and |
concrete shall act as integral compo- |
nents of the composite structure This |
unity of action is secured by the use
of twisted steel.
The requisite reduction in the elonga- |
tlon of tho steel Is accomplished by !
twisting, the twisting also affords the |
most mechanical bond, being continuous |
throughout the entire length of the bar.
1t is also noteworthy that the ultimate |
strength of the steel is increased in |
the process of twisting, and that the |
twisting i'm itself is an effective test of
the steel, for steel with inherent weak |
ness will not twist.
Tested by Fire
In the construction of reinforced con-
crete buildings, all tests of materials |
should be made upon the ground in a |
testing laboratory erected and equipped |
Tor that purpose. No greater aid to |
the successful outcome IN this method |
or construction can be had than that |
derived from practical experience, be |
il on the part of the architect con-
tractor or inspector, particularly so |
ON the part of the contractor on whom |
falls the actual manipulation of the |
materials.
Reinforced concrete has great fire
resisting qualities
After the Chicago confiagration |
commission investigated the Compare
tive fire proof qualities of the materials !
in the ruins and reported in favor of
the same in the order named: Concrete. |
brick, stone.
The conhagrations in Boston. Balti-
more and Rochester swept streets of |
granite blocks into ruins more quickly |
than II they had been of wood. Sheets |
OF tiames spread over ranges of granite |
warehouses, slate flew into fragments, |
IRON columns girders and beams
warped and bent, while the granite
blocks cracked tumbling the so-called |
hre proof piles into heaps of ruins
Probably no better and certainly no
more expensive and thorough tests
could have been devised than those I'm
Baltimore in connection with the u. S. |
Fidelity q Guaranty companys build |
ing and the International Trust COM
pany's building, both of which were
built entirely of reinforced concrete un-
der the Hennebique system.