Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02418885 2003-02-13
LIGHTVi-'EIGHT BUILDIl~TG COMPONENT
FIELD OF THE INVENTION:
This invention relates to a single very light tubular building element for
the construction of reinforced concrete intermediate floorslceilings and
roofs.
The single building element provides the formwork for the casting W place of
the
structural concrete and also provides for a high quality finished ceiling at
the
same time. It is intended for simple installation without heavy equipment into
building parts. A series of members are often intended to foxm an exposed
surface when used as a floor or ceiling.
A series of members are constructed and often arranged to be the primary
means of containing and supporting a panel or slab of concrete as it cures. ~
An
interconnected series of members, according to the present invention, also
form a
continuous mortar impervious formwork for a concrete slab; and presents an
attractive permanently exposed ceiling surface.
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of application Serial No. 091433, 593 filed
on November 2, 1999.
PRT()R ART
There have been many suggestions for use of either or both temporary or
permanent form members to construct building parts of concrete. These form
members can be temporary in nature since they are removed after concrete
cures,
or can be contained in concrete as permanent parts.
For.example:
U.S. Patent 5,953,880 teaches a modular building system of extruded
hollow thermoplastic structural components of rectilinear cross-section. These
members are made of a special. thermoplastic mixture said to resist the
elements
and are characterized by a f re-resistant outer skin. The concrete is poured
inside
CA 02418885 2003-02-13
the thermoplastic components which have internal apertures through which the
concrete can flow from one member to another member in a group when they are
joined as a wall panel, for example. When the members are to be used in
construction of a roof; concrete cannot be used, and metal inserts are called
for to
assist in stiffening.
U.S. Patent 5;729,944 discloses the use of thermoplastic structural
components as permanent formwork. The forms can be used in a series to
construct various structures. Concrete is poured inside the thermoplastic
components which have internal apertures through which the concrete can flow
from one member to another member when they are joined as a wall panel.
U.S. Patent 5,397,096 is illustrative of conventional concrete forming
techniques to manufacture a ribbed, reinforced concrete slab. The forming
system
utilizes concrete displacement pans supported on temporary framework. The
patent discloses the problem of concrete leaking out of joints. The leaking
material normally is without aggregate, and is sometimes referred to as
mortar.
When the concrete slab or slab cures, workers must remove the hardened mortar
with a chisel, or the Like, providing an unsatisfactory surface finish. The
bottom
surface is neither planar nor finished. The patent suggests the use of
additional
members to forestall the leakage of mortar.
U.S. Patents 4,557,031 and x,216,863 are illustrative of other expedients
to join extruded plastic form members for use in containing concrete inside.
The
members are normally a part of the cured concrete structure or building
component.
U.S Patent No. 5, 535, 565 is illustrative of a containment including a
plurality of panels that are interconnected by connector columns and fused
together by the passing of electrical current through conductors received
within
such elements at their points of intersection. 'the panels are interconnected
by
sliding one adjacent panel over another panel. A gasket is interposed between
a
pair of panels to create a watertight environment.
2
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U.S Patent No. 5, 535, 565 is illustrative of a highly sound insulating clay
tile for the construction of floors that has an outer substantially
parallelepiped
shape with symmetrical, laterally projecting portions that ac;t as shoulders
for the
support of each tile by prefabricated reinforced concrete floor beams.
While the field of reinforced concrete formwork is well-developed, there
is still the need for a relatively inexpensive easy-to-use system to form
ribbed-
concrete slabs with structural formwork components. The system should not be
as labor intensive as prior art a:~angements. It should use components that
are
lightweight and yet will control elastic deformation such as is often
encountered
when steel and aluminum alloy formwork is used to make such ribbed structures.
Moreover, each element should be easily aligned with an adjacent member, the
alignment means providing an impermeable alignment between adjacent
members. Thus, eliminating the need of additional members (e.g. gaskets) or
fusing of the adjacent members to accomplish impermeability.
Further, the members making up the formwork should not be filled with
concrete, to create the slab. Similarly, the members should include an easy
device
for placement of reinforcement bars without the need of manual tying or
securing
of the reinforcement bars together.
It is also desirable to have the ability to incorporate the formwork into the
slab and have it serve as an impervious formwork base, eliminating cumbersome
cleaning during construction and leakage afterward, and saving the common need
of a costly waterproofing membrane over the slab. The formwork should serve
for the casting in place of the structural concrete and also should provide
for a
high quality finished ceiling at the same time, eliminating the need to
plaster and
otherwise enhance the aesthetic appeal of the ceiling. Finally, the formwork
should facilitate hung ceiling installations and also be easily penetrable to
hold
threaded screws and the like.
BRIEF DESCRIPTION OF THE INVENTION
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There is provided an elongated tubular member arranged to be
interconnected in a series. Each member is constricted of extruded
thermoplastic
material, is relatively thin walled, and light in weight. In a preferred
embodiment,
it will weigh less than four pounds per square foot, i.e., the individual
members
weigh about 2 pounds per linear foot, so that a 5 meter long member weighs
about
32 pounds and can be handled by only one laborer without need of special
equipment. It is intended to be incorporated in structural, reinforced ribbed
concrete slabs used in roofs and floors.
The members serve as a continuous mortar impervious formwork on the
bottom of a poured concrete slab while it is curing. It thus avoids the
leakage of
concrete mortar through formwork joints during concrete pouring and cure time
which leakage can result in he>neycomb void defects that cause the structure
to be
prone to possible future corrosion of steel reinforcement contained in the
concrete
slab. Such corrosion is often difficult and costly to repair.
The formwork permanently serves as the bottom of the slab. It is an
impervious barrier of the ype essential for roof construction and thus
eliminates
the need for an exterior waterproofing membrane. The formwork has transverse,
flexural strength and stiffness sufficient to resist vertical and lateral
construction
loads without significant deformation. It can bear the weight and pressure of
wet
concrete, needing but fezv transverse intermediate temporary supports directly
under the hollow elements which make up the formwork. For example, a line of 4
X 4 wooden purlines, spaced about f ve feet apart over 4~ X 4 wooden shores,
also
spaced about five feet apart, or equivalent simple systems of metal purlines
and
shores can be used.
The members are generally formed of a PVC (polyvinyl chloride) alloy
conforming with UW form I=3uilding Code (UBC). Any UBC conforming
extrudable and light weight similar material of equal or better strength and
durability will be suitable. This general type of theremoplastic is
lightweight and
easily formed by extrusion with many integral convenient features, but has
lov~rer
modules of elasticity (stiffness) than most other construction materials. For
4
CA 02418885 2003-02-13
example, the modules of elasticity of steel is more than sixty times more than
in
thermoplastic and the modules of elasticity for aluminum is more than thirty
times
more than in thermoplastic.
The center section is Iike the hat crown and the wings are like a hat brim.
A member is defined by a top and a parallel bottom wall interconnected by
parallel side walls which are substantially perpendicular to the top and
bottom
walls. There is an internal generally horizontal wall between the enclosing
side
walls. Above that internal horizontal wall and limited by the top and side
walls is
formed a closed rectangular box-Iike conduit when viewed from an end. In that
rectangular space, it is easy to install a band of fiberglass mat to improve
thermal
insulation of the concrete slab, if desired. Below that internal horizontal
wall and
connecting it with the bottom and side walls, there is a vweb of three shorter
longitudinal internal walls. One of them is a longitudinal vertical wall
extending
from the center of the horizontal internal wall (at a central intersection) to
the
center of the bottom wal I. In one embodiment, the other two web walls are
symmetrical, sloped down and outward from the center intersection. The side
wings taper from a relatively thick area adj acent the side wall to the
narrowest
area at the end where there is a finger or groove. The sloped walls, side wall
bottom wall, and bottom left and right intersections between the bottom wall
and
side walls are thickened in the area where the wings join the side walls
thereby
forming an area better able to absorb bending stress which reduces consequent
deformation from the side wings when wet concrete is poured above them.
In a second embodiment, the two sloped walls extend symmetrically, are
sloped down and outward from a first set of two symmetrical points very close
to
the center intersection of the horizontal internal wall, through the side
walls, and
rest at points on the wings near the Left and right intersections between the
bottom
wall and the side walls. Because the sloped walls rest on the wings, they act
as
tensors and increase the stiffness of each wing sufficient to counter
deformation
caused by vertical forces acting downward on the top of the wings. In this
embodiment, there is no need to taper the thickness of all members connected
at
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the bottom right and left intersections as there is when using the embodiment
described above.
There are wing-like webs extending outwardly from each side of each
member, having a lower surface, which is substantially on the same plane with
the
outside lower surface of the bottom wall. The outermost end of one wing has an
upwardly extending finger or tongue; and the outermost end of the second wing
has a groove like an inverted ~:J, arranged upwardly with t:he opening facing
down.
The finger and groove serve a.s an alignment means. The groove-ending wing
fits
easily above the tongue-ending wing in a lapping relationship between adjacent
members when such members are Laid up in a series prepared to receive wet
concrete. Since each member has always both wing ending types, for proper lap
matching, all members for a :formwork deck shall be laid with tine tongue wing
'
ending on the same side; that side corresponding with the direction in which
the
installation proceeds.
The construction technique of the present invention facilitates hung ceiling
installations to form a plenum through which heating and air conditioning
pipes ox
ducts are passed.
Further, the construction facilitates the accurate arrangement of steel
reinforcing bars because of the unique construction of parts. The invention
permits the construction of ribbed reinforced concrete slabs with about one-
half
the weight of concrete, which might otherwise be required, which slabs are
both
resistant and stiff.
OBJECTS OF THE INVENTION
It is an object of the invention to provide lightweight, thermoplastic
structural formwork members constructed and arranged to be interconnected in a
series to serve as formwork for ribbed concrete slabs.
Another object of the invention is to provide lightweight, inexpensive, and
easy to install structural members for use in constructing ribbed concrete
slabs.
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Another object of the invention is to provide formwork for ribbed concrete
slabs that forms a continuous impervious structure, eliminating the needs for
exterior waterproofing membranes when used in roof const:rezction.
If is another object of the invention to provide formwork which has the
longitudinal and transverse flexural strength and stiffness sufficient to
resist the
weight of the wet and vertical and lateral construction loads , yet needing
few
transverse intermediate temporary supports while the concrete cures.
It is another object of tine invention to provide ribbed concrete formwork
having a pleasant appearing exposed surface capable of being used as a
finished
ceiling with regular longitudinal features or embossing which can be formed
during the extrusion process at no extra cost.
Another object of the invention is to facilitate hung ceiling installation in
commercial and institutional buildings where it is necessary to have a plenum
for
heating and air-conditioning pipes and duct work above the ceiling. The
formwork provides outward indicia or other markings indicative of areas in
which
hanger means for the ducts and pipes may be located with assurance of
sufficient
holding strength of easily penetrated material, far example, to screw in
hangers
for the hung ceiling, ducts, and pipes.
Another object of the invention is to facilitate installation of thermal
insulation for the ribbed slab.
It is yet another object of the invention to facilitate the accurate and easy
installation of steel reinforei.~g bars andlor splice bars in association with
the
formwork before pouring of the concrete.
Yet another object of the invention is to provide for construction of ribbed
reinforced concrete slabs using about one-half the normal weight and volume of
concrete as compared to conventional forming techniques.
These and other objects; features, and advantages of the present invention
will be more clearly understood and appreciated by review of the following
detailed description of the disclosed embodiments and by reference to the
appended drawings and claims.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a vertical cross--sectioxi of one embodiment of a structural
member according to this invention;
Fig. 2 is an alternate preferred structural member according to this
invention in cross-section;
Fig. 3A is a partial cross-section of a portion of two adjacent members of
the type shown in Fig. l, having a reinforcement chair with one reinforcement
bar;
Fig. 3B is a partial side view of the arrangement of the reinforcement chair
of Fig. 3A;
Fig. 4A is a partial cross-section of a portion of two adjacent members of
the type shown in Fig. 2, having a reinzforceznent chair with a plurality of
reinforcement bars (or, alternatively, a reinforcement bar and a splice bar);
Fig. 4B is a partial side view of the azzangement of the reinforcement chair
of Fig. 4A;
Fig. 5 is a transversal cross-section of a series of the tubular members 9 in
a ribbed concrete slab 60;
Fig. 5A is a detail of Fig. 5 showing a reinforcing bar 53 in the concrete
slab 60 above the longitudina:~ alignment means of an adjacent pair ofthe
tubular
members;
Fig. 5B is a perspective view of a ribbed concrete slab according to this
invention;
Fig. 6 is a schematic side elevation of an arrangement of slabs of the type
shown in Fig. 5, supported on vertical walls.
Figures 7-A, 7-B and 7-C are schematic illustrations of the elastic
deformation of the cantilever and the maximum deflection at the tip when
subject
to uniform load w, and attached to an elastic element.
8
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FIG 8A is a cross sectional view of markings on a ceiling when using the
tubular construction members according to this invention (the markings are
exaggerated in this view).
FIG. 8B is a cross sectional view of the bottom walls and wings showing
only the marks when using tubular construction members according to this
invention.
FIG. 9 is a partial cross section of two adjacent members aligned via an
alignment means having a longitzzdinal lobe.
DETAILED DESCRIPTION OF THE INVENTION
In Fig. 1 there is shown a tubular structural member 9 according to this
intention. It can be generally described as shaped like a top hat in cross-
section
with an upright central cro~~n and a flat brim about its bottom. It consists
of a
bottom surface, a top wall 10, interconnected by a pair of substantially
parallel
sidewalk 12 and 13. Protuberances 24 and 25 provide a mechanical anchorage to
the tubular member after the concrete cures, to prevent any separation of the
member from the concrete in the event that loads are hung at the bottom of the
side walls (e.g. to avoid sliding of the member).
There is a horizontal wall 18 substantially centrally of the member 9,
parallel to the top 10 and the bottom wall or floor 11. There is a. vertical
wall 19
interconnected between the bottom wall 11 and the horizontal wall I 8 at a
central
intersection 26. There are sloped walls 20 and 21 which extend downwardly and
outwardly at the same angle to the left and right of the central intersection
of the
horizontal wall 18 and the vertical wall 19, with respective opposite ends
thereof
intersecting the corners formed by the intersection of bottom 11 and side
walls 12
or 1 i, respectively. Areas 22 and 23 are referred to as the bottom left and
right
intersections.
There is a wing extending outu7ardly from each side of the member 9,
forming the brim of the top-lzat cross-section. The right-hand wing 16
terminates
in an upwardly extending finger or tongue 17. The left-hand wing 14 terminates
9
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in a receiving member 15 having an opening to receive the finger 17. In a
series
of members 9, as shown, for example, in Fig. 3, the f nger 17 or 17' is
encompassed within a receiving member 15 having an opening or groove to fit
the
finger I7. Finger 17 and the receiving member I5 act as an alignment means
that
serves only to align a series of adjacent members according to this invention.
The
alignment means does not transmit between the adjacent members any structural
load. Rather, each one of the matching wings is able to support independently
the
load directly above each wing.
The walls (sloped walls, side walls, bottom walls) and wings connecting at
the bottom left and right intersections are tapered in thickness thereby
providing
bending stiffness against rotation of these corners. The tapering of the
vt~ings
increases the stiffness of the wings which serves to absorb bending stress and
reduce consequent deformation caused by the vertical construction loads of
tile
wet concrete forces.
Each of the interior walls 20 and 2I tapers from bottom left and right
intersections 22 or 23, respectively, to the central intersection 26. The
drawings
are substantially to scale and in the illustrated preferred embodiment, the
taper of
walls 22 and 23 is from about four millimeters at the area 22 or 23 to about
tvvo
millimeters at the area adjacent to 26. The vertical wall 19 is about two
millimeters thick in the preferred embodiment. The horizontal wall 18 is about
1.5 millimeters. The top mall I 0 is about 3.2 millimeters.
The bottom wall 11 likewise tapers from the center where it is about two
millimeters to a thickness of about four millimeters just before the bottom
left and
right intersections 22 or 23. The wings 14 and 16 tape-r from about four
millimeters adjacent to a wail 12 or I3 to about 2.5 millimeters just before
the
alignment means 15 or I 7. In this embodiment, the receiving member I5 of the
alignment means is about 2.5 millimeters in thickness. The receiving member 15
is curved and in the shape of an upside down "U." The outer surface of the
curved section of the receiving member 15 has a diameter of about 7.7
millimeters. The height is about 9.5 millimeters from t:he bottom surface of
the
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wing I4 to the top of the cure c of the receiving member 15. Tlle curved
portion
ends 2.5 millimeters from the bottom of the wall to allow insertion of a
finger 17.
Finger 17 is about 2.6 millimeters thick and the opening or groove of the
receiving member is about 3.0 millimeters wide.
The sidewalk 12 and I3 are about 2.5 millimeters thick from the top wall
to the area where the horizontal wall 18 extends across the interior of the
member 9. From there, the side walls 12 and 13 taper from about 2.5
millimeters
to approximately 4.0 millimeters at the bottom left and right intersections 22
and
23, respectively, in order to increase the stiffness of the bottom left and
right
intersections. The wing I6 is about 37.I millimeters from a sidewall to the
outer
surface of the upwardly extending finger 17. The finger extends upwardly about
9.3 millimeters. The wing 14 is approximately 32 millimeters from the wall 12
to
the outside surface of the receiving member 15.
In Fig 2, there is shown a pref erred embodiment of a tubular structural
member according to this invention. The design of this alternative embodiment
eliminates the need to taper the walls of any member connected at the bottom
right and left intersections 221:, 222 (side wall, bottom wall or wing) to
control
within acceptable limits the deformation of the wings caused by the weight of
the
wet concrete.
Fig. 2 shows an embodiment that has a top 201, a bottom wall 202, and
opposed parallel sidewalls 203 and 204. There is a horizontal wall 20~
centrally
located of the member 200, parallel to the top 201 and the bottom wall 202.
There is a vertical wall 206 interconnected between the bottom wall 202 and
the
horizontal wall 20~ extending; from the horizontal wall at a central
intersection
220. A first and second sloped wall 207 and 208 extend domnwardly and
outwardly at the same angle from a first set of right 209 and left 210 points
proximate to the central intersection 220. The sloped walls 207, 208 extend
through the side walls 203, 204, with opposite ends thereof joined at the
wings
2I5, 216 at a second set of right and left points 2I 1, 212 proximate to the
bottom
right and left intersections 221, 222 formed by the bottom wall and sidewalls.
In
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other words, the opposite ends of the sloped walls 207, 208 rest on the wings
215,
21b at a point proximate to tlae intersection 221, 222 of tl.~e sidewalk 203,
204 and
bottom wall 202.
In the embodiment of Fig. 2, the tensors, 207, 208 intersect the wings at
points 211, 212, respectively, which should be proximate to the bottom left
and
right intersections 221, 222. The tensors cover a portion of the wings between
the
bottom left and right intersections 221, 222 and points 211, 212 and form a
triangle that is void of concrete. The portions of the side walls (below the
intersection of the tensors with the sidewalk) and the portion of the wings
between 211, 212 and 221, 222 respectively, are kept small to make these
portions
very rigid. As a result, the points from which the wings cantilever is from
points
211, 212 to the free ends of the wings. The result is that the bending momenf
at
the attached end of the cantilever (poinia 21 l, 212) and the deflection at
the tip of
the free end of the wings is greatly reduced. Therefore, there is no need to
taper
any wall or wing as there is in the first embodiment.
To further increase rigidity of the section of the member below the
horizontal wall, the side waPls from the right and left intersections 22I, 222
to the
horizontal wall 205 may be thicker (203b and 204b), about 3.2 millimeters
thick,
than the sidewalk that extend from the horizontal wall 205 to the top walls
201
(203a and 204a), which are about 2.~ millimeters thick.
The top wall is longer to extend slightly beyond the side walls to form
small protuberances 240, 241 which provide a mechanical anchorage to the
tubular member after the concrete cures, to prevent any separation of the
member
from the concrete in the event that loads are hung at the bottom of the side
walls.
Protuberances 240 and 241 are approximately 4 millimeters thick and project
outward about 3 millimeters.
The sloped walls 207, 208 are thinner, about 1.5 millimeters in thickness
because they are not intend°d to provide any bending stiffness, but act
as a tensor.
The horizontal wall and ver tical wall are each about 2.0 millimeters thick
and the
top wall is about 3.2 millimeters thick. 'The bottom wall or floor is about
3.0
I2
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millimeters thick. The wings are about 3.0 millimeters thick. Overall, the
thickness of each wall and wing has a thickness of 3.2 millimeters.
Points 2I l, 2I2 are about $.0 millimeters from the bottom left and right
intersections 221, 222 of sidewalls 203, 204 with bottom wall 202. The
distance
from the bottom and right intersections to the finger I7 is about 33.6
millimeters.
The distance from point 2I lto the finger is about 25.6 millimeters. The
distance
from the bottom left intersection 222 to the receiving member is about 36.2
millimeters. The distance from point 212 to the receiving member is about 20.5
millimeters.
In the construction of the embodiments shown in Figs. I, and 2, all
corners, both inside and outside, should be rounded to aid in the extrusion
process.
In Fig. 3A, which is a partial cross-section of some adjacent parts of an
adjacent pair of structural members 9, there is shown a wing 14 having a
receiving member I S ~.~ith an opening which has received within it an
upwardly
extending finger or tongue I7' on a ~Ting I6° of an adjacent member 9
for
alignment and water-proofing purposes. The fitting relationship is such that
mortar will not flow through the alignment means, thus making the deck
impermeable in nature. The alignment means includes a wing 14 that has a
receiving member 15 about .04 millimeters wider than the thickness of finger
17
to allow easy assembly, and the end of the receiving member 15 rests on top of
wing 16' and that contact is made tighter with the weight of the concrete. No
fastening device or securing device is necessary to secure the alignment of
adjacent members. This arrangement is constructed and arranged to provide a
simple way to align the members while preventing passage of mortar, thereby
creating an impermeable formwork.
It is not necessary to align the members of the pxesent invention via the
aligning means to form a deck. Each member could simply have fingers at both
ends of each wing, fingers of opposite adjacent members lying side to side.
The
purpose of the alignments mean is to create an impermeable deck. The wing of a
13
CA 02418885 2003-02-13
member having a receiving member laps the .finger of an adjacent wing. Because
the wing having the receiving member is longer and laps over the finger, it is
subject to a slight increased deflection when receiving wet concrete than that
of
the wing having the finger. This difference in deflection of the wing having
the
receiving member causes the receiving member to press dorm contacting the
adjacent wing (see Fig. 9 showing point of contact as 401 ).
The present invention also includes a reinforcement chair 50 to support
reinforcement bars. The chair 50 is removably mountable on the receiving
member 15 of the aligmnent means. Figure 3A shows a reinforcement chair 50
made also of extruded plastic, having an upward opening S l to receive a
reinforcement bar 53 and a downward opening 52 to mount the receiving member
15 of the alignment means. In this embodiment, the do~rrnward and upward
openings are curved in nature to cooperate with the curved aligunent means.
The
downward opening 52 is of sufficient size to engage in a close-ftting but
loose
relationslup with the outer surface of revolution of the opening of the
receiving
member 15. The downwardly opening 52 closely conforms to the outer surface of
revolution of receiving member 15 and has legs that extend to the top of wings
14
and 16. The upper opening S 1 is sized to accept a reinfarcing bar 53 in a
close-
fitting snap-on relationship. The legs are long enough to prevent the
reinforcement chair 50 from falling to either side.
In Fig. 3B there is shown a side elev ation of a portion of the parts of Fig.
3A, indicating the relationship of the reinforcing bar 53, the reinforcement
chair
50, and the plane in which the upper surface of the v,~ing 14 exists. The
chairs are
spaced about four feet apart.. The chairs are about one-half to three-quarter
inches
long, measuring along the axis of a reinforcing bar or "rebar" as they are
sometimes called.
In Fig. 4A there is a shown a second embodiment of the reinforcement
chair of this invention. The shape of the reinforcement chair 80 is
rectangular in
nature and would, for example, sem~e to cooperate with the alignment means
shown in Fig. 2. No embodiment is limited to cooperate with a particular
14
CA 02418885 2003-02-13
reinforcement chair and thus, may be interchangeable as long as the alignment
means are of the same shape for cooperation with the reinforcement chair.
Fig. 4A shows a reinforcement chair 80 that is elevated with legs 81, 82
above the receiving member 15 of the alignment means. The chair includes a
downward opening formed by the two bottom legs, 81 and 82, and an upward
opening formed by two upper legs 83, 84 to receive a plurality of
reinforcement
bars 90 (or a reinforcement 'bar and a splice bar}. A horizontal bar 86
extends
almost the length between the side~x~alls of two adjacent members and serves
to
divide the upper legs 83, 84 from the bottom legs 81, 8~, and also to support
the
plurality of reinforcement bars. Because of the elevated nature of the
reinforcement chair 80, it is necessary to have a horizontal bar 86 that
nearly
extends the length between two sidewalk of two members in order to prevent the
chair from falling to one side once the wet concrete is poured. Moreover, this
embodiment serves to comply with fire codes and other regulations normally
imposed in school buildings and other like buildings.
The upper legs, louver legs and horizontal bar are about 2.0 millimeters
thick. The length of the horizontal bar is about 63 millimeters. The distance
between the adjacent members in FIG. 4A is about 64.7 millimeters. The opening
between the two upper Legs is about 13 millimeters wide and the opening
between
the two lower Legs is about: 8 millimeters wide. The length of the chair is
about 1 S
millimeters.
Fig. 4B shows a side view of the reinforcement: chair shown in Fig. 4A..
The reinforcement bar 90a is directly on top of another reinforcement bar 90b
due
to the upper legs 83, 84. Ordinarily, reinforcement bars are placed right next
to
each other in the same horizontal plane and tied together manually for
purposes of
keeping such bars together in place. Tlus embodiment avoids any manual
securing of the reinforcement bars. A laborer need only drop in place the
reinforcement bars or reinforcement bar and splice bar in the chair.
In Fig. 5 there is shown a plurality of the members 9 in a ribbed concrete
slab 60. There is shown a wire mesh reinforcement sheet 6I laid on the top
1s
CA 02418885 2003-02-13
surface of the series of the plastic members ~. A series of parallel
reinforcing bars
62 are tied to the sheet 61 arranged parallel to the reinforcing b~~rs 53,
which
reinforcing bars 53 are supported by a series of reinforcement chairs 50 (not
shown). As can be seen, there is formed a series of hollow enclosed valleys.
At
the bottom of each valley, the mating alignment of adjacent members are
engaged
in mortar impervious contiguous relation.
Looking for the moment at Fig. 5A, which is a detail of a portion of Fig. 5,
parts are enlarged to better show the relationship of reinforcing bar 53 in
the
concrete slab 60.
In Fig. 5B, there is shown a perspective view of a portion of a slab
construction, shown in Fig. 5 in which the hollow tubular nature of the member
9
can be better appreciated. This view emphasizes the lightweight nature of a
ribbed slab using a series of hollow thermoplastic members according to this
invention.
In Fig. 6, there is shown a ribbed concrete slab as it might be supported in
a building. Element 63 is an outside wall and element 64 is an intermediate
wall
or beam support. Thermoplastic members 9 and 9' are shown in an appropriate
fashion supported by the walls 63 and 64. Top rebar 62 is placed exactly above
the intermediate supports as shown in FIG. 6. The exposed nature of the
ceiling is
likewise schematically demonstrated. In FIG. 6, we have shown concrete poured
about the ends of the slabs on top of the walls. There are simple means, like
tape,
provided to prevent uncured concrete from entering the plastic members 9 and
9'.
The top rebar 62 serves to resist the reverse bending farce that occurs above
the
intermediate support and also to avoid cracking through the joint between 9
and
9'. A series of such top rebars is similarly positioned across all such
interior
joints over the length and width of the structure.
Now turning to Figs. 7A-7C, as stated above, the wings project outwaxd
from the bottom left/ught intersections (Tube) in the same plane of the
bottom, as
if extensions of the bottoz:n wall fomned a ceiling. The concrete ribs of the
slab
are formed between the side walls of the parallel adjacent members and have
the
16
CA 02418885 2003-02-13
wings of those members forming the bottom of each rib and matching their edges
to prevent leakage of the mortar from the wet concrete above them. In the
first
and second embodiment, the match of the wings is at the center of rib bottom
form. Each wing carrying structurally and independently the wet concrete above
it, being in cantilever from the side wall in one embodiment and mostly in
cantilever (from the points 211, 212 outward in Fig. 2) in the second
embodiment.
Figures 7A-7C illustrate the elastic deformation of the cantilever and the
maximum deflection at the tip when subject to uniform Toad w, and attached to
an
elastic element.
Figure 7A shoves the deformation assuming the cantilever element is
elastic but the attachment (rest of the member) of it is absolutely rigid. The
tip
deformation will be called Ul.
Figure 7B shows the deformation assuming the cantilever is absolutely
rigid, but the attaching element (rest of the member) is deformable when
subject
to the bending moment caused by the cantilever element. The elastic
deformation
of the attaching element will be a rotation of the attaching plane,
represented by
the angle o. The tip of the cantilever will move downward a distance DZ = o x
S.
Figure 7C represents the actual condition, applying the principle of
superposition to the above assumptions made for Figure 7A and 7E. The actual
deflection of the tip of the cantilever being O = ~~ -i- B2. The analysis
shows the
importance and the need to control the rotation of the point of attachment of
the:
wing to reduce B by reducing d2.
As a result, there is a need to provide substantial stiffness both to the
wings in cantilever and to the tube at the two bottom corners where these
wings
are attached, to avoid unpleasant deflection of the wings. In the first
embodiment
shown in FIG. l, this is done by providing the bottom left and right
intersections
formed by the sidewalk and bottom wall (including sloped walls) with bending
stiffness against rotation of these corners. The tapered thickness of these
walls,
thicker at the bottom left and right intersection and thirmer at the other
ends, is an
effective form to obtain thc~ needed rigidity. In the second embodiment, a
thin
CA 02418885 2003-02-13
tensor extends out to the top of each wing, reducing the cantilever portion of
the
wing and the forces that cause rotation of'the bottom right and left
intersections.
With these conditions, the uniform thickness is rigid enough and easy to
extrude.
It can also be appreciated that the structure of this invention, including the
plastic members 9 facilitate hung ceiling installation in commercial and
industrial
buildings where it is necess~~ry to have plenums to pass heating and air-
conditioning ducts and pipe s. In tlae embodiment shown in Figs 8A and 8B,
longitudinal markings 300 at the intersection of the side walls 203, 204 with
the
bottom wall 202 serve to delineate the boundaries of the side walls 203, 204
so
that a threaded screw or other like material can be placed in the middle 301
of tkie
bottom of the side walls 20 3, 204. As shown in FIG 8B, after installation of
a
slab constnzction according to this invention, these marlced areas 300 will be
detectable on the exposed ceiling surface (the variation in thickness of the
wings
and bottom walls in FIG 8A and 813 are exaggerated for exemplary purposes).
Threaded screws easily penetrate the plastic material from which members 9 are
made of and are much Iess expensive and easier to install than power-driven
nails
and the like, which normally are used with concrete slabs. The variation in
thickness between the wings and sidewalk is about .5 millimeters.
The hollow interior of the structural members 9 and 40 facilitate the
installation of thermal insulation, for example, by filling the longitudinal
tubular
portions with fiberglass, either blown or by inserting pieces of insulation
mats.
Another embodiment for the alignment means is shown in Fig. 9 which
includes a~z alignment means having a finger with a longitudinal lobe 400. The
lobe 400 is a means of separation that serves to ensure that the finger 17
does not
come in direct contact with the left inner side of the receiving member 15, to
avoid capillary action to raise water between them. As shown in Fig. 9, the
receiving member comes in contact with the uTing having the ringer at point
401.
Use of the members according to this invention facilitates the accurate and
precise arrangement of steel reinforcing bars, not only because of the novel
seat
18
CA 02418885 2003-02-13
construction, but because it can be accomplished without the cost of the labor
involved in tying reinforcing wires which is the usual practice.
Construction according to this invention provides for reinforced concrete
slabs of about one-half the weight and concrete volume. The slabs are
resistant t:o
sagging. Approximately 80 millimeters or x.25 inches average thickness of
concrete (from top of slab to top of wings buried in concrete) can be used to
build
a roof slab span of about six meters or 20 feet. In residential intermediate
size
floor slabs, they can be up to about five meters or 16 feet at the same
concrete
thickness. Conventionally, she latter would require 1~0 millimeters or six
inches
in normal ribbed reinforced concrete slab.
The time and labor required to build a ribbed concrete slab, according to
the invention, is substantially reduced for many reasons. For example, the
task of
placing the formwork is much simpler because the present invention is a single
component that can be installed easily and efficiently without heavy equipment
or
special craftsmanship; afterward the component is not m°moved, but
stays
permanently integrated in the concrete floor or roof. Additionally, the amount
of
time to install slab reinforcement is drastically reduced because there is no
need to
wire the reinforcing bars in place. Since about one-half the volume of
concrete is
required, additional time and labor are saved. No formwork stripping is
needed.
Ceiling plastering, painting and the like can be eliminated.
In the above description, exemplary dimensions have been given in
describing the operation. of structural members when incorporated in a ribbed
concrete slab forming process. It should be understood by those skilled in the
art
that other dimensions can be calculated, using conventional techniques, to
deternzine appropriate dimensions for installations other than exemplary ones
described herein.
For performance verification we have used properties of available
thermoplastic material. It should be likewise understood that plastic
materials
other than the exemplary one descr ibed above which will provide the
properties
19
CA 02418885 2003-02-13
described to a member made therefrom are considered the functional equivalent
of those described herein and can thus likewise be used.
Having thus described the invention in detail, what is claimed is:
