CA2324966C - Lightweight building component - Google Patents

Abstract

A ribbed concrete structural form using a series of lightweight extruded plastic structural formwork members for use in constructing ribbed concrete floor, ceiling, and roof slabs. The members comprise an elongate tubular conduit essentially rectilinear in cross-section, and formed by a pair of substantially parallel side walls, a floor, and a top. There is substantially centrally located a longitudinal interior horizontal web substantially parallel to the top and floor thereof, and extending between the parallel walls to form upper and lower passageways through the interior of the conduit. There is a vertical web parallel to the side walls, and extending from the interior horizontal web to the floor substantially centrally thereof to form a group of longitudinal spaces. There is also a first and second sloped web extending downwardly and outwardly in opposite directions at an angle acute to the intersection of the horizontal web and the vertical web with opposite ends of the sloped webs joining at the intersection of each lateral wall and the floor. The floor extends beyond the parallel side walls on each side to form substantially flat bottomed wing-like projections. The outer longitudinal edges of each wing include longitudinal mating connecting means arranged to seat in a sealing relationship when a plurality of the members are interconnected to form a slab. The sealing relationship is sufficiently impermeable to prevent the flow of constituents of the concrete being cast above them. There are a series of seats or chairs arranged to be placed over the connecting structure of an adjacent pair of wing edges in the sealing relationship and to support the reinforcing bars above the wings substantially parallel to support the connecting means.

Description

=10/25!00 11:49 FAX 954 7424505 __CA 02324966 2000-11-01,LE q09 'EL 4-4928'5865US
LIGHTWEIGHT BUILDING COMPONENT

FIELD OF THE INVENTION:
This invention relates to elongated extruded thermoplastic tubular components intended for incorporation into building parts such as roofs, ceilings, and floors.
Such components are often intended to form an exposed surface when used as a floor or ceiling. They are often incorporated as part of a poured concrete structure.
A series of components 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 thermoplastic structural components, according to the present invention, also form a continuous mortar impervious formwork for a concrete slab, and presents an attractive permanently exposed ceiling surf ace .
PRIOR 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 structural parts.
For examplei 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 fire-resistant outer skin. The concrete is poured inside the thermoplastic components which have internal apertures through which the Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biogar Page 009 10/25/,00 11:49 FAX 954 7424505 CA 02324966 2000-11-01LLE 1M010 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 pad 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 5,216,863 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.
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 Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 010 10/25/,00 11:50 FAX 854 7424505 _TCA 02324966 2000-11-011LE QO11 slabs with struatural formwork components. The system, should not be as labor intensive as prior art arrangementa.
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. It is also desirable to have the ability to incorporate the formwork into the slab and have it serve as a mortar impervious formwork base, thereby eliminating the need for external water-impervious membranes needed, for example, when the slab is to serve as a roof.

BRIEF DESCRIPTION OF THE INVENTION
There is.provided an elongated tubular element arranged to be interconnected in a series. Each element is constructed 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 handed 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 elements 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 honeycomb void defects which degrade appearance and cause the structure to be prone to possible future corrosion of steel reinforcement Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 011 - 10/25/.00 11:50 FAX 954 7424505 CA 02324966 2000-11-OLLE 012 contained in the concrete slab. Such corrosion is of-ten difficult and costly to repair.
The formwork permanently serves as the bottom ofthe slab. it is an impervious barrier of the type 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 few 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 five 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 PVC (polyvinyl chloride). That is, the center section is like the hat crown and the side walls are like a hat brim. The members are defined by a top and a parallel bottom wall interconnected by parallel side walls. There are wing-like webs extending outwardly from each side, having a lower surface which is co-planar with the outside lower surface of the bottom wall. The outermost end of a first side wing has an upwardly extending finger or tongue arranged to seat in a contiguously close-fitting relationship in a downwardly opening groove of an adjacent member in the opposite wing when the members are laid up in a series they are prepared to receive wet concrete. The second wing of each member thus includes such a downwardly opening longitudinal groove as its terminus.
There is an internal horizontal wall between the Received Oct-25-00 11:46am From-954 T424505 To-Smart & Biggar Page 012 - 10/25/,00 11:50 FAX 954 7424505 CA 02324966 2000-11-01,LE Q013 enclosing side walls, which side walls are substantially perpendicular to the top and bottom walls to form a closed box-like conduit when viewed from an end, which conduit is divided by the horizontal wall.
In addition, there is a vertical, longitudinal web or wall extending between the bottom of the horizontal internal web or wall and the bottom. There are sloped longitudinal webs extending outwardly from the central intersection between the internal, horizontal wall and the internal vertical wall. The sloped webs are substantially equal in length. They extend from the intersection of the horizQntal.and vertical walls to the opposite lower corner where a side wall joins the bottom.
The side wings taper from a relatively thick area adjacent the side wall to the narrowest area at the end where the finger or groove is formed. The sloping webs, side wall bottoms, and floor all are thickened in the area where the wings join the side walls thereby providing increased strength and forming an area better able to absorb bending stress which may be imparted from the side wings when wet concrete is poured above them.
The construction technique of the present invention facilitates hung ceiling installations to form a plenum through which heating and air conditioning pipes or ducts are passed.
The invention facilitates the installation of thermal insulation, when necessary, by allowing the placement of insulation in the hollow tubular construction elements supporting the ribbed concrete structure. 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 Received Oct-25-00 11:46am From-954 7424505 To-Smart & Bissar Page 013 10/25400 11:51 FAX 954 7424505 _CA 02324966 2000-11-01õLE Q14 reinforced concrete slabs with about one-half the weight of concrete, which might otherwise be required, which slabs ..are both sag.resistant and stiff. For example, about 8 millimeters or three and a quarter inch average thickness of concrete can be used as a roof slab for a six meter or 20 foot span. in a residential intermediate floor, a slab to about five meters or 16 feet is possible with the same thickness slab. There is additional substantial savings in steel reinforcement.

OBJECTS OF THE INVENTION
It is thus an object of this invention to provide improved method and means of constructing ribbed concrete building slabs.
It is another object of the invention to provide lightweight, thermoplastic structural 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.
Another object of the invention is to provide formwork for ribbed concrete slabs which forms a continuous mortar impervious structure, eliminating the needs for exterior waterproofing membranes when used in roof construction.
It is another object of the invention to provide formwork which has the longitudinal and transverse flexural strength and stiffness sufficient to resist the vertical and lateral construction loads incurred by the pressure of wet concrete, yet needing few transverse intermediate temporary supports while the concrete cures.
It is another object of the invention to provide Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 014 10/25/00 11:51 FAX 954 7424505 CA 02324966 2000-11-01,LE 1M 015 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 indicative of areas in which hanger means for the ducts and pipes may be located with assurance of sufficient holding strength and a critical mass of easily penetrated material, for example, to screw in hangers for the hung ceiling, ducts, and pipes. Alternatively, one may score a line or form a ridge that is outwardly detectable and indicates easily penetrable area, without time consuming measuring that are also susceptible to mistake.
Another object of the invention is to facilitate installation of thermal insulation in the ribbed slab.
It is yet another object of the invention to facilitate the accurate and easy installation of steel reinforcing 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.

Received Oct-25-00 11:46am From-954 7424505 To-Smart & Blssar Pase 015 10/25/00 11:52 FAX 954 7424505 CA 0_2324966 2000-11-01LE f~j018 BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a vertical.cross-section of a.
preferred embodiment of a structural member according to this invention;
Fig. 2 is an alternate structural member according to this invention in side elevation and cross-sectiont Fig. 3 is a partial cross-section of a portion of two adjacent members of the type shown in Fig. 1, having, a reinforcement seat;
Fig. 4 is a partial side view of the arrangement of the reinforcement seat of.Fig. 3;
Fig. 5 is a transversal cross-section of a series of the tubular members 9 in a ribbed concrete pad 60;
Fig. 5A is a detail of Fig. 5 showing a reinforcing bar 53 in the concrete pad 61 above the longitudinal connecting means of an adjacent pair of the 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.
Fig. 7 is a schematic illustration of the weight distribution of concrete when using of tubular construction members according to this invention.

DETAILED DESCRIPTION OF THE INVENTION
In Fig. 1 there is shown a tubular structural member 9 according to this invention. it can be generally described as shaped like a top hat in cross-section with an upright central crown and a flat brim about its bottom. it Received Oct-25-00 11:46am From-954 7424505 To-Smart & Bi&sar Page 016 10/25/00 11:52 FAX 964 7424506 CA 02324966 2000-11-011E CM017 cons3sta of a bottom surface or floor 11, a top wall 10, iaterconnected by a pair of substantially parallel side walls 12 and 13. The side walls 12 and 13 have longitudinal ribs or protuberances 24 and 25,, respectively, which assist in holding the tubular structural member 9 in place in a concrete slab.
There is a horizontal web 18 substantially centrally of the conduit 9, parallel to the top 10 and the bottom wall 11. There is a vertical web 19 interconnected between the bottom wall 11 and the horizontal web 18. There are sloped webs 20 and 21 which extend to the right and left of the intersection of the horizontal web 18 and the vertical web 19, with respective opposite ends thereof intersecting the corners formed by the intersection of bottom 11 and side wall 12 or 13, respectively. That area of intersection, for example, on the left at 22 and on the right at 23, is thickened to provide a mass of plastic material of sufficient depth to hold hanger members for a suspended ceiling, duct work, pipes, and the like. This thickened area also provides increased flexural strength for the member 9. Likewise, there is a longitudinal thickening mass of plastic at 26 at the intersection of the central ends of the webs 20 and 21, and the top of the vertical web 19, all interconnecting with each other and the center interior web 18.
There is a wing extending outwardly from each side of the member 9, forming the brim of the top-hat cross-section. The right-hand web 16 terminates in an upwardly extending finger or tongue 17. The left-hand wing 14 terminates in a downwardly opening, longitudinal groove 15.
In a series of inembers 9, as shown, for example, in Fig. 3, Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 017 10/25/00 11:52 FAX 954 7424505 _.,CA 02324966 2000-11-01ALE Q018 the finger 17 or 17, is encompassed within a downwardly.
opening groove 15.
Each of the interior walls 20 and 21 tapers from the enlarged area 22 or 23, respectively, to the.enlarged mass of plastic material at 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 two millimeters at the area adjacent to 26. The vertical wall 19 is about two millimeters thick in the preferred embodiment. The interior web 18 is about 1.5 millimeters. The top wall 10 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 thickened area 22 or 23..
The wings 14 and 16 taper from about four millimeters adjacent to a wall 12 or 13 to about 2.5 millimeters just before the connecting means 15 or 17. The connecting means 15 is about 2.5 millimeters in thickness. The outer surface of its curved section has a diameter of about 7.7 millimeters. The height is about 9.5 millimeters from the bottom surface of the wing 14 to the top of the curve of the member 15. The curved portion ends 2.5 millimeters from the bottom of the web to allow insertion of a finger 17. Finger 17 is about 2.5 millimeters thick and the groove mouth is about 2.7 millimeters wide.
The side walls 12 and 13 are about 2.5 millimeters thick from the top wall 10 to the area where the horiaontal web 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 Received Oct-25-00 11:46am From-954 7424505 To-Smart & BlsBar Page 018 10/25/00 11:53 FAX 954 7424505 CA 02324966 2000-11-01ALE Q019 thickened areas 22 and 23, respectively. The web 16 is about 37.1 millimeters from a side wall 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 groove 15.
The thickened areas at 22 and 23 are about 10 millimeters from the bottom surface of the floor 11 to the top of the thickened area.
In Fig 2, there is shown an alternative embodiment of tubular structural members according to this invention.
There is shown a generally rectilinear shape having a top 40, a bottom wall 41,'and opposed parallel side walls 42 and 43. There is a pair of internal intersecting webs 46 and 47. The interior webs and the side walls are of sufficient thickness so as to prevent excessive flexing.
The inventive concepts would enable one skilled in the art to calculate and determine the required thickness as a function of the applied load. Similarly, the wings and connecting means are of sufficient thickness so as to control within allowable tolerance the deflection of the free end of the wings.
Bottom corn rs 51 include thickened masses of plastic arranged to receive hangers for ceiling, pipe, and duct work.
There are a pair of longitudinal ribs 44 and 45 which serve the same purpose as the webs 24 and 25 in Fig. 1.
internal ribs 44A & 45A are necessary to increase the buckling resistance of wall 42 and 43 under concentrated vertical constructions loads.

Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biuzar Paae 019 10/25/00 11:53 FAX 954 7424505 CA 02324966 2000-11-01AI.E
-- . , --- -- - - - CM0 2 0 In the conatructions of both Figs. 1 and 2, all corners, both iiiside and outside, should be rounded to aid in the extrusion process.
In Fig. 3, which is a partial cros-s-section of some adjacent parts of an adjacent pair of structural members 9, there is shown a wing 14 having a downwardly opening groove 15 which has received within it in a close-fitting relationship an upwardly extending finger or tongue 17' on an adjacent web 16, of an adjacent member 9. The close-fitting relationship is such that mortar will not flow through the connecting means. The fitting relationship includes a wing 14. has a downw,ard opening groove 15 about .02 millimeters wider than the thickness of finger 17 to allow easy assembly, and the end of the groove 15 rests on top of wing 16 and that contact is made tighter with the weight of the concrete. This fitting arrangement is constructed and arranged to prevent passage of mortar.
There is shown a seat or chair 50, made also of extruded plastic, having upwardly and downwardly opening grooves. The downwardly opening groove 52 is of sufficient size to engage in a close-fitting but loose relationship with the outer surface of revolution of the downwardly opening groove 15. Groove 52 is of sufficient length to prevent rotation about the connecting means. The upper groove 51 is sized to accept a reinforcing bar 53 in a close-fitting snap-on relationship. The downwardly opening groove closely conforms to the outer surface of revolution of element 15 and has legs that extend to the top of wings 14 and 16. The legs are long enough to prevent the seat from falling to either side.
In Fig. 4 there is shown a side elevation of a portion of the parts of Fig. 3, indicating the relationship of the Received Oct-25-00 11:46am Fram-954 7424505 To-Smart & Biqgar Page 020 =10/25/00 11:53 FAX 954 7424505 CA 02324966 2000-11-01&LE

reinforcing bar.53, the seat 50, and the plane in which the upper surface of-the wing 14 exists. The seats are spaced about four feet apart. The seatp 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. 5 there is shown a plurality of the members 9 in a ribbed concrete pad 61. There is shown a wire mesh reinforcement sheet 61 laid on the top surface of the series of the plastic members 9. A series of parallel reinforcing bars 62 are tied to the sheet 61 arranged parallel to the reinforcing bars 53. As can be seen, there is formed a series of hollow enclosed ribs between which _ are formed open valleys. At the bottom of each valley, the mating connecting means of adjacent webs 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 pad 60.
In Fig. 5B, there is shown a perspective view of a portion of a slab construction, shown in Fig. 5 in which the open 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 91 are shown in an appropriate fashion supported by the walls 63 and 64.
Top rebar 62 is placed only above the intermediate supports as shown in FIG. 6. The exposed nature of the ceiling is Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 021 10/25/00 11:54 FAX 954 7424505 _ CA 02324966 2000-11-01ALE 022 likewise schematically demonstrated. In.FIa. 6, we have shown concrete poured about the ends of the slabs on top of the,walls. There is means provided to prevent uncured concrete from entering the plastic members 9 and 9': The top rebar 62 serves to resist the reverse bending force 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.
It can also be appreciated that the structure of this invention, including the plastic members 9 with thickened plastic masses such as 22 and 23 facilitate hung ceiling installation in commercial and industrial buildings where it is necessary to have.plenums. to pass heating and air-conditioning ducts and pipes. After installation of a slab construction according to this invention, these thickened areas will be detectable on the exposed ceiling surface.
Threaded hangers which are useable in the plastic material from which members 9 are made are much less expensive and easier to install than power-driven nails and the like, 'which normally are used with concrete slabs.
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.
Use of the members according to this invention facilitates the accurate and precise arrangement of steel reinforcing bars, not only because of the novel chair construction, but because it can be accomplished without the cost of the labor involved in tying reinforcing Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 022 _.10/25/00 11:54 FAX 954 7424505 __CA 02324966 2000-11-O1kLE IM023 wires which is the usual practice.
Construction according to this invention provide4:'for reinforced concrete slabs of about one-half the weight'and concrete volume. The slabs are resistant to sagging..
Approximately 8 millimeters or 3.25 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, the latter would require 150 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. 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 and the like can be eliminated.
The configuration of the proposed tubular members of this invention and the loading are symmetrical about a vertical axis passing through the center of the tubular member.
In Fig. 7, there is shown a typical transverse load distribution of concrete poured above a structural member, according to this invention. For purposes of considering this Figure, there is used letters to discuss the stress distribution across component members.
As mentioned above, the loads are symmetrical about the central axis Y that passes through the vertical member Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 023 10/25/,00 11:55 FAX 854 7424505 ___..CA 02324966 2000-11-011LE [M024 E-F. Noting the lower portion of the lateral side of the tubular member, it can be seen that the height B-C is about one-half or less than the height of the member B-D, and therefore, B-C is more than twice as stiff as B-D. As mentioned in the description of Fig. 1, various-walls, including wall B-C, have variable thicknesses to cause the member to be stiffer along the axis of rotation at points B
and B'. With the same amount of plastic material, the variable thickness allows a component to exhibit stiffness and resistance to flexing caused by rotation at the thicker end which is almost double the stiffness exhibited by a similar_tubular member having constant wall thickness. The top of the tube which, in part, forms the deck for the ribbed concrete slab is shown in the diagram to have a concrete weight W2 as compared to the weight W, which rests on adjacent wings A-B and A'-B'. The generally triangular side diagrams show the lateral pressure of concrete from th bottom W3 to the top W4 of each member. The horizontal internal web between points C and C' restrict to nil the horizontal displacement of points C and C' relative to axes B-D and B'-D', respectively, and aid in stiffening the sides of the tubular member to resist rotation about the longitudinal axes B and B', which can result from cantilever like action of the wings about points B and B'.
The diagonal or sloped members B-F and B'F', which are inclined in opposite directions, avoid displacement of the wall end points E and F relative to axis B-B', and therefore stiffen the floor between B-B' to resist rotation about the axes of rotation B and B' when the wings are loaded.
As has been elsewhere described, the underside, or bottom, of the tubular members can be an exposed and be the Received Oct-25-00 11:46am From-954 T424505 To-Smart & Biggar Page 024 10/25/00 11:55 FAX 954 7424505 CA 02324966 2000-11-01kLE
~ 025 finished ceiling of a slab system. Incremental deflection of. the longitudinal'wing end points A-A' in relation to floor B-B' is not not-iceable. The construction of an element, according to this invention,. including the variable thickness of the wings resist deformation and avoids the unsightly possibility of significant movement out of a horizontal plane by the ends of the wings.
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 determine 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 described above which will provide the properties.
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:

Received Oct-25-00 11:46am From-954 7424505 To-Smart & Biggar Page 025

Claims (22)

1. Claim 1. Tubular lightweight and extruded plastic structural members for use in constructing ribbed concrete floor slab, ceiling slab, and roof slabs comprising, an elongated tubular member essentially rectilinear in cross-section, and formed by a pair of substantially flat side walls, a floor wall, and a top wall, there being substantially centrally located intersecting webs interconnected between the walls forming the member to longitudinally enclose a plurality of hollow conduit sections in the interior of the member, the bottom surface of the floor wall extending beyond the parallel side walls on each side of the member to form a pair substantially flat bottomed longitudinal wing-like projections, the bottom of the wings and the floor wall thus lying in substantially the same plane, the outer longitudinal edge of each wing including connecting means constructed and arranged to interconnect with complimentary means on a next adjacent wing edge when a plurality of the members are interconnected to form an exposed surface of a floor slab, a ceiling slab, or a roof slab.
2. Claim 2. In the tubular structural member of Claim 1, there being a series of fastening devices arranged to hold the complimentary connecting means of an adjacent pair of wing edges in frictional engagement, the fastening devices including structure to support reinforcing bars above and substantially parallel to the wing connecting means of adjacent wings when concrete is being cast upon a group of interconnected structural members.
3. Claim 3. In a tubular structural member of Claim 1, there being protuberance means longitudinally along the outer side wall constructed and arranged for engagement by adjacent cured concrete in a slab.
4. Claim 4. In the tubular structural member of Claim 1, the wings being gradually tapered from the thickest portion adjacent a side wall to the thinnest portion adjacent the connecting means.
5. Claim 5. In the tubular structural member of Claim 1, there being a sufficient mass of thermoplastic material longitudinally of the member to threadedly receive hangers of the type used to hang suspended ceilings.
6. Claim 6. In the tubular structural member of Claim 1, there being longitudinal decorative embossing formed during the extrusion of said member.
7. Claim 7. An elongated tubular member, the member being generally rectilinear in cross-section, having four longitudinal walls, comprising a pair of side walls, a floor, and a top, there being substantially centrally located a horizontal wall substantially parallel to the top and the floor, and extending between the side walls to form upper and lower hollow conduit sections of the interior of the member, there being an upright wall substantially parallel to the side walls, and extending from the horizontal wall to the floor substantially centrally thereof, there also being a first and a second sloped wall each extending downwardly and outwardly at approximately the same angle from the intersection of the horizontal wall and the vertical wall with opposite ends thereof joined to the intersection of a side wall and the floor, the bottom surface of the floor extending beyond the side walls on each side of the member, but lying in substantially the same plane, and serving as the flat bottom or wing-like longitudinal projections on each side of the member, the outer longitudinal edge of each wing including cooperating connecting means arranged to interconnect with a next adjacent wing edge when a plurality of the conduits are interconnected to form a concrete form.
8. Claim 8. In the tubular member of Claim 7, there additionally being a spaced series of fastening devices arranged to hold the connecting structure of an adjacent pair of wing edges in frictional engagement.
9. Claim 9. In the tubular member of Claim 7, there additionally being means to support reinforcing bars above the wings substantially parallel to the connecting structure of the wings when concrete is being cast upon an assembled group of the structural members.
10. Claim 10. The tubular member of Claim 7, wherein the wings are substantially thicker at their respective intersections with adjacent side walls, but gradually tapering to a lesser thickness at the connecting means.
11. Claim 11. Lightweight extruded plastic structural formwork members for use in constructing ribbed concrete floor slabs, ceiling slabs, and roof slabs comprising, an elongated tubular conduit essentially rectilinear in cross-section, and formed by a pair of substantially parallel side walls, a floor wall, and a top wall, there being substantially centrally located a longitudinal interior horizontal web substantially parallel to the top wall and floor wall thereof, and extending between the parallel side walls to form upper and lower passageways through the interior of the conduit, there being a vertical web parallel to the side walls, and extending from the interior horizontal web to the floor wall substantially centrally thereof, there being a first and a second sloped web extending downwardly and outwardly in opposite directions at an acute angle to the intersection of the horizontal web and the vertical web with opposite ends of each said sloped web joining a side wall at the intersection of a side wall and the floor wall, the floor wall extending beyond the parallel side walls on each side of the tubular conduit to form substantially flat bottomed wing-like projections, the bottom surface of the wings and the floor wall lying in substantially the same plane, the outer longitudinal edge of each wing including longitudinal connecting means arranged to interconnect with longitudinal connecting means at the edge of a next adjacent wing edge in a sealing relationship when a plurality of the formwork members are interconnected to form a floor slab, a ceiling slab, or a roof ribbed concrete slab, the sealing relationship between the connecting means of adjacent wings being sufficiently impermeable when assembled to prevent the flow of constituents of the concrete being cast above them, there being a series of fastening devices arranged to hold the connecting structure of an adjacent pair of wing edges in the sealing relationship and including, means to support reinforcing bars above the wings substantially parallel to the connecting means of adjacent wings when concrete is being cast upon the assembly of a group of the tubular members, and wherein the wings are substantially thicker at their respective intersections with adjacent parallel side walls, and tapering to a lesser thickness at the connecting means, the intersection of the floor wall, sloped webs and adjacent side walls characterized by material sufficient to allow insertion of hanger means for a suspended ceiling or the like.
12. Claim 12. A method of fabricating a cast-in-place ribbed concrete slab comprising, a) horizontally assembling a group of plastic hollow tubular structural members across vertical walls to be spanned by the slab, the members of the group each including longitudinal connecting means arranged to be mated in a mortar impervious relationship across the span, b) assembling the members to form a series of parallel raised hollow enclosed ribs and depressed open valleys, c) mating the connecting means of adjacent members in mortar impervious contiguous relation in the depth of said valleys, d) fixedly suspending a series of longitudinal reinforcing bars in said valleys between but parallel to adjacent ribs, e) laying reinforcing wire mesh across the top of the ribs, f) placing additional reinforcing bars upon or below said wire mesh, g) pouring concrete to a depth sufficient to immerse said ribs, screen, and reinforcing bars supported therein, and fill said valleys, and h) fixing the member in said concrete while it is curing.
13. Claim 13. Tubular lightweight and extruded plastic structural members for use in constructing ribbed concrete floor slabs, ceiling slabs, and roof slabs comprising, an elongated tubular member essentially rectilinear in cross-section, and formed by a pair of substantially flat side walls, a floor wall, and a top wall, there being substantially centrally located an intersecting pair of webs, a first of the pair of webs extending between the side walls and a second of the pair of webs extending between the first web and the floor wall, thereby dividing the member longitudinally into a plurality of hollow conduits, the bottom surface of the floor wall extending beyond the parallel side walls on each side of the member to form a pair of substantially flat-bottomed longitudinal wing-like projections, the bottom of the wings and the floor wall lying in substantially the same plane, the outer longitudinal edge of each wing including connecting means constructed and arranged to interconnect with complimentary means on a next adjacent wing edge when a plurality of the members are interconnected to form an exposed surface of a floor slab, a ceiling slab, or a roof slab.
14. Claim 14. The reinforcing structure of Claim 13 in which the plastic reinforcing members weigh less than four pounds per square foot of slab.
15. Claim 15. The tubular structure of Claim 13 in which the series of members are characterized by sufficient transverse flexural strength to resist vertical and lateral construction loads in a slab containing them.
16. Claim 16. The tubular structure of Claim 13 in which the plastic members are made of extruded polyvinyl chloride.
17. Claim 17. The tubular structure of Claim 13 in which intersections of walls of the members have sufficient longitudinal mass to absorb bending stresses.
18. Claim 18. The tubular structure of Claim 17 in which there is observable indicia from which the thickened mass of material can be located.
19. Claim 19. In the tubular structural member of Claim 13, there being a series of seats constructed and arranged to maintain the complimentary connecting means of an adjacent pair of wing edges in frictional engagement, the seats further including structure to support reinforcing bars above and substantially parallel to the wing connecting means when concrete is being cast upon a group of interconnected structural members.
20. Claim 20. In a tubular structural member of Claim 13, there being a longitudinal rib along each outer side wall constructed and arranged for engagement by adjacent cured concrete in a slab.
21. Claim 21. In the tubular structural member of Claim 13, the wings being gradually tapered from a thickest portion adjacent a side wall to the thinnest portion adjacent the connecting means.
22. Claim 22. The tubular structural member of Claim 13, wherein the connecting means consists of an upwardly extending finger-like ridge along one wing edge and a complimentary downwardly opening groove along the other wing, the finger and groove constructed and arranged to frictionally engage in a substantially mortar impervious mating relationship.