Concrete form using face sheet as tension flange for stiffeners

Abstract

Metal concrete form panels having a face sheet to which is attached a rearwardly extended perimeter flange. Stiffeners on the back side of the face panel are to the back side of the face sheet and are arranged so that pressure on the front of the face sheet induces a tensile force in the face sheet.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates generally to metal concrete forms and, more specifically, to a metal concrete form panel which uses the face sheet as a tension flange for the stiffeners.

[0003] 2. Background of the Prior Art

[0004] Concrete forming apparatus is in wide use in the construction of buildings, bridges, and other concrete structures. A common system for forming concrete structures uses a plurality of modular form components that are adapted to be assembled into a wide variety of configurations to conform to virtually any architectural requirement. Such forming apparatus components are typically made of metal so that they are strong enough to support the heavy weight of poured concrete and durable so that the components can be reused many times.

[0005] One of the most commonly used configurations of such metal form components is a flat panel that is used in forming substantially flat concrete surfaces, such as walls, foundations, pillars, and the like. Such metal concrete form panels have a face sheet which is in contact with the concrete being poured. A rearwardly extended flange is secured around the perimeter of the face sheet. A plurality of spaced apart stiffeners are tied to the perimeter flange and tie rods or similar components are used to tie the flanges to the flanges of the wall panel on the opposite side of the wall being formed. Since the face sheet spans rib to rib, the welded stiffeners induce compression stress in the face sheets, particularly when a force is exerted against the face sheet by the concrete. If the compression force is large enough, the face sheet will deflect between the ribs and the finished concrete will have a pillowed appearance. Walers, external stiffeners and the like are attached to the back side of the form panel in an effort to reduce the compression forces induced on the face panel and thereby reduce the likelihood that it will deflect. The use of such stiffeners is time consuming and adds to the inventory of form components that must be kept in inventory. Further, they add to the weight of the forms and so require stronger, more expensive equipment to move around the construction site and make the forms more difficult to maneuver into place by workers.

[0006] In recent years, new, higher strength concrete formulations have been introduced and are becoming widely used in the construction of poured concrete structures. Many of these new concrete formulations are less viscous than conventional concrete formulations and they tend to take longer to cure. Accordingly, there is a greater quantity of uncured, liquid concrete that must be contained by the forms during pours. There is also a demand for concrete forming systems that can contain larger quantities of uncured concrete. For example, over the past several years, the capacity of pumps for supplying concrete has increased from 50 cubic yards per hour to 150 cubic yards per hour and form systems that can contain this larger volume of concrete are needed.

[0007] There is a need for metal concrete form panels that are light in weight yet sufficiently strong to resist deflecting during forming of concrete structures without the need for the attachment of additional or external stiffening members.

SUMMARY OF THE INVENTION

[0008] The invention consists of a metal concrete form panel having an increased resistance to deflection and pillowing when used to contain and form concrete. The form panel comprises a face sheet to the back of which are attached at least two spaced apart transverse ribs and at least two spaced apart tie ribs. A rearwardly extended flange extends around the perimeter of the face sheet. The ribs are spaced inside the perimeter flange and around the central portion of the face sheet. Tie rods used to secure the form panel to other concrete form components or supporting structures are positioned adjacent the tie ribs. The transverse ribs span continuously through the tie ribs so that when uncured concrete is pressing against the face sheet, the ribs distribute the force to place the face sheet to always be in tension and the ribs in compression and making it fully effective for calculating the cross sectional properties of the ribs. The face sheet becomes the tension flange for the welded ribs and stiffeners and so acts as an integral part of the form panel that resists bending forces of the concrete. While a conventional form panel will be specified for use at a given pressure, the form panel of the present invention constructed of the same weight steel will be specified and twice the pressure even though weighing only approximately ten percent more than the conventional form panel.

[0009] An object of the present invention is to provide a metal concrete form panel that has a face panel placed in tension to provide increased resistance against deflecting or pillowing without the use of additional or external stiffening members.

[0010] Another object of the invention is to provide a concrete form component that resists deflection and pillowing under load without substantial additional weight or cost of manufacture.

[0011] These and other objects of the invention will be made apparent to those skilled in the art upon a review and understanding of this specification, the associated drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a perspective view of a modular concrete form component of the present invention.

[0013] FIG. 2 is cross-sectional view taken along line 2-2 of FIG. 1.

[0014] FIG. 3 is an enlarged perspective view of a tie rod receiving channel and associated opening in the face sheet of the form panel.

[0015] FIG. 4 is a plan view of a form panel of the present invention assembled with other concrete form components for the forming of a T-shaped wall section.

[0016] FIG. 5 is a schematic diagram showing the compressive forces induced on a face sheet of conventional form panels.

[0017] FIG. 6 is a schematic diagram showing the tensile forces induces on a face sheet of form panels of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] Referring to the drawings, there is illustrated in FIG. 1, generally at 10, a metal concrete form panel of the present invention. The form panel includes a face sheet 12 on its front surface and a rearwardly extended flange 14 that extends around the perimeter of the face sheet, including a pair of opposing end rails 16a and 16b and a pair of opposing side rails 18a and 18b. The flange 14 is secured to the face sheet 12 by weldments or the like.

[0019] In the preferred embodiment, a pair of tie ribs 20a and 20b extend between the side rails 18a and 18b and are secured by weldments or the like to the back side of the face sheet 12. A plurality of cross ribs 22 are arranged on the back side of the face sheet 12, extended between the end rails 16a and 16b. In the preferred embodiment, each of the cross ribs 22 includes a central, cross rib section 24 and a pair of cross rib end sections 26a and 26b. The sections 24, 26a and 26b are secured to the back side of the face sheet 12 by weldments or the like.

[0020] The tie ribs 20 are of a substantially J and S-shape in transverse cross section, having a base leg 28 (S-shaped), a central web 30 and a top leg 32 (FIG. 2). The tie ribs 20 are secured to the face sheet 12. The tie ribs 20a and 20b are arranged in a spaced-apart relation on either side of a central portion of the face sheet 12. The cross ribs 22 are substantially J-shaped in transverse cross-section with the end portion of the leg section of the J being secured to the back side of the face sheet 12 and the base of the J extended parallel to the face sheet 12.

[0021] The form panels 10 are held in a spaced apart relation to other concrete form components to create a space in which the fresh concrete is poured to form the section of concrete. For example, in forming a wall section, a pair of the form panels 10 will be positioned with their face sheets facing each other and separated by the desired thickness of the wall being formed. A concrete form assembly for forming a T-shaped wall section is illustrated in FIG. 4. A form panel 10 is assembled with a pair of comer form assemblies 23. Tie rods 25 are used to assist in holding the form panel 10 at the desired position relative to the comer form assemblies 23. In conventional form panels, the tie rods are positioned adjacent where two adjacent panels meet each other at the perimeter flange. In assembling form panels 10 of the present invention, the tie rods 25 are positioned adjacent the tie ribs 20. A receiving tube 27 (FIG. 3) is secured to the tie ribs 20 in four symmetrically arranged locations (FIG. 1). A tie rod 25 will pass through the receiving tube 27, a corresponding opening 29 in the face sheet 12 (FIG. 3), and span the wall forming space to be attached to another component of the form assembly (FIG. 4).

[0022] When used in forming a concrete structure using the form panels, whether of the conventional type or of the present invention, the fresh or liquid concrete is poured so that it is in contact with the front side of the face sheet of the panel. The concrete imposes a force on the face sheet that is in a generally normal direction. In conventional form panels, with the stiffeners secured to the perimeter flange, the force of the concrete places the face sheet in compression, as illustrated in the schematic diagram of FIG. 5. In contrast, the force of the concrete on the face sheet 12 of a form panel 10 of the present invention induces a tensile force in the face sheet 12, as illustrated in the schematic diagram of FIG. 6. The face sheet 12 thus forms an integral part of the structural components of the panel 10, with the result that the form panel 10 provides a much greater resistance to deflection or pillowing than conventional form panels.

[0023] The form panels can be of any size desired for use in the concrete forming industry. In a preferred embodiment the form panel 10 is 8 feet square. There are two tie ribs 20a and 20b that are spaced inwardly of the end rails 16a and 16b, respectively, by one foot, ten and one-half inches. There are seven cross ribs 22, one of which is located in the middle of the form panel 10 midway of the side rails 18 and the other six of which are spaced equidistant of the central cross rib 22, with three each on either side. The tie ribs 20 are formed of one-quarter inch thick ASTM A607 Grade 50 steel, with the central web 30 being eight and one-quarter inches long and the base leg one and one-half inches long. The cross ribs 22 are made of one-eighths inch thick ASTM A570 Grade 50 steel, with the leg section eight and one-quarter inches long and the base section is one and one-half inches long. The rails 14 and 16 and the face sheet 12 are made of one-quarter inch thick ASTM A607 Grade 50 steel. A comparable conventional panel is sold under the name Plate Girder® by EFCO Corp. An 8′-0″ rib Plate Girder will deflect 0.036 inches between the ribs at the specified capacity and 0.194 inches from side to side for a total deflection of 0.230 inches. A form of the present invention will deflect less than 0.125 inches in most applications. The resulting form panel 10 thus has twice the rated capacity of a comparable conventional form with roughly one-half the deflection and only a ten percent increase in weight.

[0024] Although the invention has been described with respect to a preferred embodiment thereof, it is to be also understood that it is not to be so limited since changes and modifications can be made therein which are within the full intended scope of this invention as defined by the appended claims.

Claims

1. A metal concrete form panel, comprising: (a) a face sheet; (b) a flange extended rearwardly of the face sheet around the perimeter of the face sheet; (c) a plurality of stiffeners extended between opposing portions of the flange and secured to the back of the face sheet; and (d) the stiffeners are arranged around a central portion of the face sheet so that pressure on the front side of the face sheet induces a tensile force in the face sheet.

2. A metal concrete form panel as defined in claim 1 wherein said face sheet is rectangular.

3. A metal concrete form panel as defined in claim 2 wherein said face sheet is square.

4. A metal concrete form panel as defined in claim 1, wherein said stiffeners include at least a first pair of generally parallel, spaced-apart stiffeners.

5. A metal concrete form as defined in claim 4, wherein said stiffeners include at least a second pair of stiffeners transverse to the first pair of stiffeners.

6. A metal concrete form panel as defined in claim I wherein the cross section of the face sheet resists deflection substantially equally with the cross section of the ribs.

7. A metal concrete form panel, comprising: (a) a rectangular face sheet; (b) a flange extended rearwardly of the face sheet around the perimeter of the face sheet; (c) at least two spaced apart stiffeners transverse to a first pair of opposing sections of the flange and having opposite end portions secured to corresponding opposing sections of the flange; (d) at least two spaced apart stiffeners transverse to a second pair of opposing sections of the flange and having opposite end portions secured to corresponding opposing sections of the flange; and (e) the stiffeners are arranged around a central portion of the face sheet so that pressure on the front side of the face sheet induces a tensile force in the face sheet.