US3496691A - Concrete forms - Google Patents

Description

P. A. SEABURG A CONGRETE FORMS Filed Aug. 2, 1968 Feb. 24, 1970 lA/VEA/TORS Pau/ Jeabury o) fl/berf J Ol/dhcusden Jr:

United States Patent 3,496,691 CONCRETE FORMS Paul A. Seaburg, Mequon, Wis., and Albert J. Oudheusden, Jr., Bethlehem, Pa., assignors to Bethlehem Steel Corporation, a corporation of Delaware Filed Aug. 2, 1968, Ser. No. 749,640 Int. Cl. E04b 1/16, 5/18 US. Cl. 52336 4 Claims ABSTRACT OF THE DISCLOSURE A sheet metal concrete form intended for use in floor and roof construction. The form serves initially as a support for wet concrete and temporary construction loads, and finally as the main positive reinforcement for the concrete slab when the concrete has set and cured. The form has a plurality of alternating dovetail grooves and triangular closed ribs. The ribs are perforated so that concrete is able to enter and fill the interior of the ribs and lock the concrete slab to the sheet metal form and create an integral composite slab.

BACKGROUND OF THE INVENTION This invention relates to concrete forms and more particularly to forms made of sheet metal which are left permanently in place after the pouring of concrete for roof and floor slabs in buildings.

Roofs and floors for commercial and industrial buildings are often constructed by placing a series of wooden or sheet metal forms on the tops of supporting joists and girders, spacing steel reinforcing bars or mesh above the forms and then depositing a layer of fresh concrete on the forms and around the reinforcement to the desired slab thickness. With this type of construction the form serves only as a support for the fresh concrete and, in many cases, is stripped or removed once the concrete has set and cured. Contractors usually find the removal of the forms from the underside of the slabs, not only difficult but also time consuming and expensive. For this reason many contractors prefer to use forms which can be left permanently in place.

Heretofore in situations where the forms have been permanently left in place, the forms contributed very little to the strength or load carrying capacity of the finished slab. The strength of the slab was obtained primarily from the concrete and conventional reinforcing bars or mesh embedded in the concrete. It generally was not possible to get sufficient bond between the concrete and the top surface of the form which would permit the form and slab to act as a composite unit and thereby permit the loads imposed on the finished floor to be carried to the supporting girders and joists.

In addition, since many of the slabs serve as ceilings for the floor below, it was usually necessary to install false ceiling to hide the rather unattractive undersides of the forms.

Many of the heretofore known forms also were expensive, diflicult to install and unsuited to serve as a support for piping, ducts, electrical conduits, false ceilings and the like which are used regularly in modern building construction.

SUMMARY OF THE INVENTION It is therefore an object of this invention to provide a permanent metal form for concrete floor slabs or the like which also Serves as the main positive reinforcement for the finished concrete slab.

It is a further object of this invention to provide a permanent metal form for concrete floor slabs or the like 3,496,691 Patented Feb. 24, 1970 which will coact compositely with the concrete in the slab when subject to loads.

It is a still further object of this invention to provide a permanent metal form for concrete floor slabs or the like which is easy to install, presents a smooth, attractive appearance on the underside and can serve as a support for suspended ceilings, pipes, ducts and the like.

Other and further objects of this invention will become apparent from the following description and the accompanying drawing and claims.

It has been discovered that the foregoing objects can be attained by a sheet metal form having a plurality of spaced parallel perforated substantially triangular closed ribs formed on the top surface thereof.

BRIEF DESCRIPTION OF DRAWINGS The figure is a perspective view, partially in section, of a concrete slab constructed according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the figure, the form 1 is fabricated from a rectangular metal sheet and is designed to rest upon and extend between joists or girders 2 spaced at suitable intervals. The forms 1 are preferably made of galvanized steel for high strength and long life.

As shown in the figure, the forms 1 have a continuous, substantially flat bottom surface 3 and a top surface comprising a plurality of dovetail troughs 4 separated by a plurality of parallel, substantially triangular ribs 5. The sidewalls 6 of each rib 5 abut one another at the base of the rib 5 thereby forming a closed hollow cell 7 within the rib 5.

The sidewalls 6 of each rib 5 are provided with a series of relatively large diameter apertures 8 which connect the hollow interior of the cell 7 with the dovetail troughs 4. The apertures 8 are staggered so that an aperture 8 in one sidewall 6 of a rib 5 is located approximately midway between two adjacent apertures 8 in the other sidewall 6 of the same rib 5.

The side edges of the form 1 are designed to permit interlocking of adjacent sheets. One edge is bent to form a short, upturned curved flange 9 while the opposite side edge is bent to form a short, downturned curved flange 10 as a short projection of the outer sidewall 6 of the last rib 5.

As illustrated in the figure, adjacent forms 1 are placed with the ribs 5 extending perpendicular to the joists or girders 2, and are snapped together into locking engagement by placing the outermost rib 5 of one form 1 over the upturned flange 9 at the side edges of the adjacent sheet. Pressing or stepping on the rib 5 will drive the flange 9 in between the converging sidewalls 6 of the rib which in turn will press against the upturned flange 9 causing it to fit tightly against the short downturned flange 10 of the overlapping form 1.

Since the bottom surface 3 of the form 1 is flat and continuous and the ribs 5 are closed at the bottom, there is no need to provide end closures or to tightly abut the ends of adjacent sheets together to prevent concrete leakage as is usually the case with conventional corrugated forms.

When the forms 1 are in place, they are secured to the tops of the girders or joists 2 by welding, self-tapping screws, clips or the like. In the embodiment shown in FIGURE 1, shear connectors 14 in the shape of short channels are welded to the tops of forms 1 and girders 2 to provide composite action in a direction parallel to the girders. Any of the other well known types of shear connectors could be used in place of the channels 14, if desired.

If rewired, electrical ducts or conduits (not shown) can be placed in the trough 4 or across the tops of the ribs 5 before placing the concrete 11 on top of the forms 1.

After all the forms 1 are properly positioned and secured to the girders and joists 2, a layer of fresh concrete 11 is poured on top of the forms 1 to the desired depth. The concrete 11 not only fills the dovetail troughs 4 but also covers the ribs 5 and enters into the hollow interior of the ribs 5 through apertures 8 and substantially fills the hollow cells 7 as shown in the figure.

If desired, lightweight welded steel wire fabric 12 may be placed slightly below the upper surface 13 of the concrete slab 11 to reduce cracking due to shrinkage and temperature changes.

During the pouring of the concrete 11, the form 1 serves as a support for the wet concrete and the workmen. However, once the concrete 11 has set and cured, the metal form 1 serves as the main positive reinforcement for the concrete slab. The unique combination of the dovetail troughs 4 and the apertures 8 in the sidewalls 6 of the ribs 5 provide a strong mechanical bond that tightly locks the concrete slab 11 to the steel reinforcing form 1.

As a result of the excellent concrete to steel bond, and the resulting composite action, one is able to eliminate the need for conventional reinforcing bars or mesh in the slab with the result that construction costs can be greatly reduced.

A preferred embodiment of this invention is a form approximately 18 inches wide having three 2 inch high ribs spaced 6 inches apart. The apertures punched in the sidewalls of the ribs are inch diameter holes spaced 3 inches apart. The lengths of the form range from about 6 to 15 feet. The forms are constructed of galvanized steel in thicknesses between 18 and 26 gauge.

What is claimed is:

1. A concrete slab construction, in combination, a plurality of overlapping rectangular metal backing sheets,

said sheets having a plurality of spaced parallel perforated hollow closed ribs projecting from one surface thereof and a layer of concrete on said sheets covering said ribs and substantially filling the hollow interior of said ribs.

2. A backing for receiving, supporting, strengthening and interlocking with cementitious material comprising a rectangular metal sheet having a plurality of spaced parallel perforated hollow closed ribs projecting from one surface thereof.

3. A form for receiving, supporting, strengthening and interlocking with cementitious material comprising a rectangular metal sheet having a continuous, substantially flat bottom surface and a top surface comprising a plurality of dovetailed troughs separated by parallel substantially triangular ribs, the two sidewalls of each rib meeting at the base of said rib forming a closed hollow cell, said sidewalls being provided with a series of apertures extending between the hollow interior of said cell and the dovetailed troughs.

4. The form of claim 3 in which the perforations in one of said sidewalls are offset from the perforations in the other sidewall.

References Cited UNITED STATES PATENTS 764,989 7/1904 Chester 52450 FOREIGN PATENTS 278,186 10/1927 Great Britain.

HENRY C. SUTHERLAND, Primary Examiner J. L. RIDGILL, JR., Assistant Examiner US. Cl. X.R.

Images