Improvements in Concrete Floors.
Year: 1895

page_text: Improvements in Concrete Floors.
I, ALBERT LINCOLN JOHNSON, of St. Louis, in the State of Missouri, United
States of America, Civil Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention relates to concrete floors and has for its principal objects to increase
the strength and rigidity of such floors and reduce the cost of making them. It
consists in the arrangements and in the combinations of parts hereinafter
described.
The main support of my floor consists of parallel 1-beams, supported by the frame
of the building. Over the tops of adjacent beams are fastened the ends of strong
suspension straps or saddles, preferably of wrought iron or steel and thin enough to
be quite flexible. The ends of these straps or saddles, extend beyond the further
edge of the beams and are bent to conform to the shape of the beam so as to lie
close against the same, while the middle portion of the strap or saddle bends or
curves down. The curve which a flexible flat wrought iron or steel strap naturally
assumes when its ends are supported at fixed points nearer together than the length
of the strap is the line of stable equilibrium of such strap for supporting a vertical
load distributed like a concrete floor; that is, the application of the concrete floor
on such a strap does not tend to change the form of its curve but produces a tensile
stress only therein.
Upon each of these straps or saddles, as a bottom, concrete is filled in up to the
horizontal level desired so as to constitute a stiffening or strengthening rib. Upon
the tops of the several ribs, extending fro.n one rib to another are laid bars or strips
of metal, preferably sheets of expanded or open-work metal. The I-beams of
concrete floors are generally protected from fire by having haunches of concrete
built up on their lower flanges. In my construction, the tops of these haunches are
level with the tops of the ribs, and serve also to support the expanded metal, which
extends sidewise beyond the ends of the ribs, to rest on said haunches, the expanded
metal being cut to straddle the suspension straps.
Upon the expanded metal is laid plastic concrete to any desired thickness, and
upon this layer of concrete is laid any desired kind of flooring.
In making my floor, the suspension straps, are first fitted over adjacent I-beams
and adjusted parallel at the proper distance apart. Then suitable false-work is
built up to form side boxing for the strengthening ribs, and haunches, and also to
form a bottom for supporting the expanded metal, said bottom being flush with the
tops of said ribs. The plastic concrete is then filled in such boxing to form the
ribs and haunches and then the expanded metal is laid on the tops thereof. Then
the main layer of concrete is laid upon the expanded metal and worked through the
interstices therein so as completely to fill the same, the false-work supporting the
expanded metal and preventing waste of concrete. When the concrete hardens
the false work is removed.
On account of the interstices of the expanded metal being filled with concrete,
its tensile strength is very great. Other materials, such as strips or wove wire,

page_text: may be substituted for expanded metal with fair results, but on account of the
peculiar formation of the expanded metal, it has special advantages of its own.
Dated this 25th day of November 1895.
Improvements in Concrete Floors.
I, ALBERT LINCOLN JOHNSON, of St. Louis, in the State of Missouri, United
States of America, Civil Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention relates to concrete floors and has for its principal objects to increase
the strength and rigidity of such floors and reduce the cost of making them. It
consists in the arrangements and in the combinations of parts hereinafter
described.
In the accompanying drawings
Figure 1. is a cross sectional view of my construction on the line 1 to 1 of
Figure 3, with the top flooring mounted thereon.
Figure 2. is a cross-sectional view on line 2 to 2 of Figure 3, shewing the
suspension-strap and rib in elevation and with the top flooring removed.
Figure 3. is a plan view of the construction shown in Figure 2. with the concrete
partially broken away to show the expanded metal sheet.
Figure 4 is a perspective detail of the expanded metal, and
Figure 5 is a sectional detail through the concrete and expanded metal.
The main support of my floor consists of parallel I-beams, 1, supported by the
frame of the building. Over the tops of adjacent beams are fastened the ends of
strong suspension straps or saddles, 2, preferably of wrought iron or steel and thin
enough to be quite flexible. The ends of these straps or saddles, 2, extend beyond
the further edge of the beams and are bent to conform to the shape of the beam so
as to lie close against the same, while the middle portion of the strap or saddle
hends or curves down. The curve which a flexible flat wrought iron or steel strap
naturally assumes when its ends are supported at fixed point nearer together than
the length of the strap is the line of stable equilibrium of such strap for supporting
a vertical load distributed like a concrete floor; that is, the application of the
concrete floor on such a strap does not tend to change the form of its curve but
produces a tensile stress only therein.
Upon each of these straps or saddles, 2, as a bottom, concrete is filled up to the
horizontal level desired so as to constitute a stiffening or strengthening rib, 3.
Upon the tops of the several ribs, 3, extending from one rib to another are laid
bars or strips of metal preferably sheets of expanded or open-worked metal, 4.
The I-beam of concrete floors are generally protected from fire by having
haunches, 5, of concrete built up on their lower flanges. In my construction the
tops of these haunches are level with the tops of the ribs 3, and serve also to
support the expanded metal, 4, which extends sidewise beyond the ends of the
ribs, 3, to rest on said haunches, the expanded metal being cut to straddle the
suspension straps.
Upon the expanded metal is laid plastic concrete 6, to any desired thickness, and
upon this layer of concrete 6, is laid any desired kind of flooring, 7.
In making my floor, the suspension straps, 2, are first fitted over adjacent I-beams
and adjusted parallel at the proper distance apart. Then suitable false-work is

page_text: built up to form side boxing for the strengthening ribs, 3, and haunches, 5, and
also to form a bottom for supporting the expanded metal, 4, said bottom being
flush with the tops of said ribs, 3. The plastic concrete is then filled in such
boxings to form the ribs and haunches and then the expanded metal is laid on
the tops thereof. Then the main layer of concrete, 6, is laid upon the expanded
metal, 4, and worked through the interstices therein so as completely to fill the
same, the false-work supporting the expanded metal and preventing waste of
concrete. When the concrete is hardened the false work is removed.
On account of the interstices of the expanded metal being filled with concrete,
its tensile strength is very great. Other materials, such as strips or wove wire may
be substituted for expanded metal with fair results, but on account of the peculiar
formation of the expanded metal it has special advantages of its own.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A floor consisting of beams, suspension straps fastened at the tops thereof and
curved down in the intermediate portion in the line of stable equilibrium, concrete
ribs on said straps, strips of metal on said ribs and a layer of concrete on said strips,
substantially as described.
2. A floor consisting of beams, suspension straps fastened at the tops thereof and
curved down in the intermediate portion in the line of stable equilibrium, concrete
ribs on said straps, sheets of expanded metal on said ribs and a layer of concrete on
said expanded metal, substantially as described.
3. A floor consisting of flanged beams, suspension straps having their ends
fastened at the top thereof and curved down in the intermediate portion in the
line of stable equilibrium, concrete ribs on said straps, haunches on the flanges of
said beams, sheets of expanded metal on said ribs and haunches, and a layer of
concrete on said expanded metal, substantially as described.
Dated this 25th day of August 1896.