US3792830A

US3792830A - Concrete beam forms

Info

Publication number: US3792830A
Application number: US00273737A
Authority: US
Inventors: S Dashew; A Wills
Original assignee: Mesa Industries Inc
Current assignee: Mesa Industries Inc; LA MESA IND Inc
Priority date: 1970-04-22
Filing date: 1972-07-21
Publication date: 1974-02-19
Anticipated expiration: 1991-02-19

Abstract

Apparatus for forming concrete beams integrally with concrete floors comprising an elongated beam form with bottom and side walls and with flanges extending outwardly from the top of the side walls. A pair of rods projected upwardly through holes in opposite flanges, are tied by a steel strap to prevent spreading of the side walls when concrete is poured into the form. After the concrete sets, the rods are pulled out, the form stripped, and the strap left in place. The elongated beam forms have end portions, where the lower walls are stepped down and the side walls stepped outwardly, and a pair of aligned beam forms is joined by an adjustment form section which lies within the stepped end portions of the beam forms.

Description

Dashew et al.

CONCRETE BEAM FORMS [75] Inventors: Stephen S. Dashew, Los Angeles; Arnold Wills, Lakeview Terrace, both of Calif.

[73] Assignee: La Mesa Industries, Inc., Compton,

Calif.

[22] Filed: July 21, 1972 [21] Appl. No.: 273,737

Related U.S. Application Data [62] Division of Ser, No. 30,872, April 22, 1972, Pat. No.

[52] U.S. Cl. 249/28, 249/48 [51] Int. Cl. E04g 11/42 [58] Field of Search 249/26, 28, 48, 49, 50, 17,

[56] References Cited UNITED STATES PATENTS 1,675,749 7/1928 Crawford 249/26 1,282,200 10/1918 Des Lauriers 249/48 944,543 12/1909 Des Lauriers.... 249/26 1,119,969 12/1914 Longevin 249/26 1,331,096 2/1920 Eaches 249/26 1,143,107 6/1915 Des Lauriers.... 249/26 1,616,354 2/1927 Comer 249/192 X .1451 Feb. 19,1974

Primary Examiner-J. Spencer Overholser Assistant Examiner.lohn S. Brown Attorney, Agent, or Firm-Lindenberg, Freilich & Wasserman [5 7 ABSTRACT Apparatus for forming concrete beams integrally with concrete floors comprising an elongated beam form with bottom and side walls and with flanges extending outwardly from the top of the side walls. A pair of rods projected upwardly through holes in opposite flanges, are tied by a steel strap to prevent spreading of the side walls when concrete is poured into the form. After the concrete sets, the rods are pulled out, the form stripped, and the strap left in place. The elongated beam forms have end portions, where the lower walls are stepped down and the side walls stepped outwardly, and a pair of aligned beam forms is joined by an adjustment form section which lies within the stepped end portions of the beam forms.

1 Claim, 10 Drawing Figures CONCRETE BEAM FORMS This is a division, of application Ser. No. 30,872 filed Apr. 22, 1970, now US. Pat. No. 3,735,953.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to concrete forming apparatus and methods, and more particularly, to forms and methods for producing concrete beams integrally with concrete floors or ceilings.

2. Description of the Prior Art Concrete floors with integral beams have generally been constructed by building plywood decks with gaps, and building plywood troughs along the gaps to form the beams. In order to prevent spreading of the trough sides under the weight of the concrete, wires are inserted through the form to hold the trough sides together. Such wires, generally referred to as form ties, are inconvenient to thread through structural steel located in the beam region. In addition, the wires have the disadvantage that they generally are tapered to permit removal from the set concrete, which makes them expensive. Also, the patching of the holes left by the withdrawn wire is easily seen in the finished structure, since the patches are located in the downwardly extending beam.

A new beam-forming trough is constructed for each beam, and disassembled after the beam is formed. This repeated construction of troughs out of plywood and their disassembly, is time consuming and therefore expensive. However, it is resorted to because many different lengths of beams are used in the usual building, so it would be difficult to repeatedly use only one or a few forms. Also, a one-piece form that enclosed the beam from below would be difficult to remove from the set concrete. I

OBJECTS AND SUMMARY OF THE INVENTION An object of the present invention is to provide forms for constructing concrete beams at building sites, which is more economical than forms available heretofore and which provides beams of better appearance.

Another object is to provide a method for constructing concrete beams which is more economical and which provides beams of better appearance than heretofore.

In accordance with one embodiment of the present invention, beam forms are provided which have a bottom wall, side walls extending upwardly from the bottom wall, and flanges extending outwardly from the top of the side walls. Pairs of rods can be projected upwardly through holes in the opposite flanges to hold the ends of straps that brace the side walls against outward spreading when the form is filled with concrete. After the concrete is set, the rods are pulled out, the form removed, and the straps left in place in the floor region above the beam. The holes from which the rods have been removed are patched, but the fact that these holes are in the ceiling near the beams makes the patches hardly noticable.

In order to facilitate removal of the forms from set concrete, they must be flexible to permit the flanges to pivot down and the side walls to spread apart. However, in many cases, the walls also should be stiff to hold concrete without deflecting excessively. A fiberglass form is employed that can bend, and its bottom wall, side walls and flanges are braced by sheets of plywood. The corners of the form are left uncovered by plywood so they can flex to permit the sides and flanges to deflect away from the concrete during removal.

The beam forms are constructed to permit them to be used for beams of various lengths, so that the same forms can be used many times in constructing a building where almost all beams are of different lengths. To permit this, the beam forms have end portions with a down-stepped bottom wall and outstepped side walls. An adjustment form section is employed to bridge the end portions of two aligned beam forms, the adjustment section lying on the down-stepped bottom walls and within the out-stepped side walls. The ends of the beam forms can be spaced from each other within a range of distances, and still can be bridged by the adjustment form. An adjustment form can be constructed as an intersection to connect four beam forms.

The novel features of the invention are set forth with particularity in the appended claims. The invention'will be best understood from the following description when read in conjunction with the accompanying drawmgs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, partially sectional, of a beam form constructed in accordance with one embodiment of the invention;

FIG. 2 is a sectional end view of the beam form of FIG. 1, shown after the pouring of concrete therein;

FIG. 3 is a partial side view of beam forms of the type shown in FIG. 2;

FIG. 3A is a side elevation view of the forms of FIG. 3, showing their removal from side concrete;

FIG. 4 is a plan view of a star intersection form for joining four beam forms of the type shown in FIG. 1;

FIG. 5 is a plan view of a form assembly for constructing an integral beam and column;

FIG. 6 is a side elevation view of the form assembly of FIG. 5i

FIG. 7 is a sectional end view of a flexible beam form constructed in accordance with another embodiment of the invention;

FIG. 8 is a view of the form of FIG. 7 after concrete has been poured therein; and

FIG. 9 is a view of theform of FIG. 8 during removal of the form from set concrete.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, the invention provides a beam form 10 which can form a concrete beam 12 that is integral with a concrete floor 14. Most of the concrete floor I4 is formed by a deck 16 of plywood or the like, with elongated gaps therein which can receive beam forms 10. After the deck and beam forms are in place, and steel bars have been positioned, which are to remain in the set concrete to reinforce it, concrete is poured over the structures to fill the beam form and the region above the deck 16. When the concrete sets, the deck 16 and beam form 10 must be stripped away, to leave a concrete floor with integral beams. In many cases, the beams may be left exposed in the finished building. After one floor is formed, the'next higher floor is formed by building another deck and positioning the beam forms along gaps in it. It should be understood that the term floor. refers to the type of structure rather than its use, and such structures often serve primarily as ceilings to cover a space.

The beam form includes a body 18 of a resilient material such as resin-impregnated fiberglass, that has been molded into the shape of a pan with flanges. The body includes a lower or bottom wall 20, a pair of

side walls

22, 24 extending upwardly from either side of the bottom wall, and a pair of

flanges

26, 28 extending outwardly from the top of each side wall. The fiberglass body 18 is resilient enough to be deformed, and therefore, in some cases it must be stiffened to prevent excessive deflection or even failure under the weight of I concrete poured into it. Accordingly, stiff bracing members in the form of sets of

plywood sheets

30, 32, 34, 36 and 38 are applied to the outside surfaces of the walls of the fiberglass body. The edges of the plywood bracing sheets are spaced from each other to leave gaps at the corners of the form, so that the

side walls

22, 24 can be spread apart, and the

flanges

26, 28 pivoted downwardly during removal of the beam form from the set concrete.

The ability of the form side walls to spread apart for removal, necessitates the use of means for holding the sides together during the pouring of concrete into the form. The great weight of concrete in the form would wires were tapered to facilitate their removal after the concrete was formed. The concrete beams and floor generally include mazes of reinforcing steel bars and wires, some of which are shown at 40, and the threading of numerous form wires through the reinforcing steel members added to the cost of construction. Instead of using such removable form wires, straps 42 are employed as tensile members which extend through the floor region of the concrete structure.

In accordance with the invention, means are provided to employ the straps 42 to hold the beam form 10 against spreading under the weight of concrete poured therein. Accordingly, holes 44, 46 are provided in the

flanges

26, 28 and

flange bracing structures

36, 38 to permit the projection of

rods

48, 50 therethrough which can engage holes in the strap 42. The

rods

48, 50, which serve as tie holding members, are long bolts with reduced diameter ends 52 that can project through holes in the strap 42. The flange structures, each composed of a

flange

26 or 28 and

plywood sheets

36 or 38 thereunder, have plates 54 fixed to their undersides, each plate carrying athreaded nut 56. The

rods

48, 50 are each threaded along a portion spaced from their tips, so that they can be screwed into the nuts 56 and held in place. After the rods are thus installed, the strap 42 can be installed by laying it in place, with the holes atits ends engaged by the tips 52 of the rods.

' After the concrete floor structure with integral beams has been formed and the concrete has set,'the decks beneath the floors can be removed and the beam forms can be removed. Removal of a beam form is accomplished by first removing the

rods

48, 50. This is sides of the form outwardly. When the beam form 10 has been removed, the strap 42 will still remain in place, and two holes will be present in the ceiling of the concrete structure where the two rods were removed. These holes can be patched, if desired. The fact that the holes are in the ceiling of the structure lessens the possibility of water seepage therein, and makes then and any patchworkon them, less apparent than if the holes were in the beam 12.

The size of the straps 42 can be fairly large, so that they can be spaced a considerable distance such as several feet apart along the length of the beam forms. The large bracing force which the straps can provide is reliably transmitted through the

strong rods

48, 50, and distributed by the strong flange structures to the sides of the beam form. Of course, a reduction in the number of rods and straps to be installed considerably lowers the amount of work required to install and remove them and to perform any patching of the holes they leave.

Generally, there is no standard length of beams between columns or other end structures. In some buildings, columns of continually decreasing width are utilized so that the beams of successively higher stories in the building are of successively longer length. If a different beam form had to be employed for each different beam length, then a large number of forms would have to be stocked and delivered to each building site. In order toeliminate the need for large numbers of forms of different lengths, beam form apparatus is provided which facilitates adjustment of beam length. As shown in HO. 1 and 3, each beam form 10 has end portions 60 wherein the bottom wall 20E of the fiberglass body is down-stepped, the

opposite side wall

22E and 24E are out-stepped and the

opposite flanges

26E and 28E are down-stepped. As shown in FIG. 3, a pair of beam forms 10A and 108 may be aligned to construct a long beam, and an adjustment form section or form 62 can be employed to bridge the two beam forms. The adjustment section 62 is essentially a short length of a fiberglass beam form without down-stepped or outstepped ends, and without sheets of bracing plywood. The down-stepped and out-stepped end portions of the beam forms 10A and 10B are stepped only far enough so that the upper surface 645 of the bottom wall 64 of the adjustment form section is even with the upper surfaces 20S of the beam forms 10A and 108. Similarly, the out-stepping of the side walls is just far enough to accommodate the thickness of the adjustment section, and the down-stepping of the flanges is just enough to accommodate the thickness of the adjustment section flanges;

In order to prevent the leakage of concrete around the ends of the adjustment section, strips 66 and 68 of tape are applied to the inner surfaces of the intersection of the beam and adjustment forms. If the gap between the two beam forms 10A and 10B is large as compared to the length of the adjustment section 62, the tape strips 66 and 68 would have to cover a wide gap between the upper surfaces 205 of the beam forms and upper surface 643 of the adjustment section. The tape may not be strong enough to support concrete across such a gap. In such a case, filler strips such as strip 70 can be laid in the gap, on the bottom and side walls and on the flanges. Thus, only a limited number of beam forms is required to construct concrete beams of a variety of lengths, by providing adjustment sections which can lie in appropriately constructed end portions of the beam forms. Of course, it is possible to construct each beam form with one end stepped in the manner described, and the other end plain. In that case, the plain end of each beam form would fit into the stepped end of another form, so that no separate adjustment form section would be required.

As shown in FIG. 3, the ends of the adjustment section 62 are tapered at an angle A such as 20 from the vertical (as seen in a side elevation view). Similarly, the ends of the forms A and 10B whichjoin to the adjustment section 62 are tapered'or inclined from the vertical. Such inclining facilitates removal of the forms from set concrete, as shown in FIG. 3A, which illustrates two forms 10A and 10B and an adjustment section 62 extending between two

columns

71, 73. A slight downward movement or pivoting of one form 10A to position 10A helps to free that form from the column 71 and adjustment section 62, by creating a gap between formerly abutting surfaces.

The design used for the adjustment section can be employed to enable the joining of more than two beam forms, as at an intersection of four forms shown in FIG. 4. As shown in that figure, and adjustment section in the shape of a star intersection 80 is provided to join four beam forms 10C, 10D, 10E and 10F. The star intersection is a simple fiberglass form which is coupled to the ends of the beam forms in the same manner as the adjustment form section 62 described above. That is, the four ends of the star intersection are received in the down-stepped and out-stepped end portions of the beam forms, and tape strips 82 are employed to seal the insides of the star intersection to the beam forms.

The ends of the beam forms can be constructed to provide a beam which merges into a column. FIGS. 5 and 6 illustrate a beam form 90 with an end 92 that partially encompasses a column region to form part of a cylindrical column 94. A half-column form section 96 with flanges98 extends l80 about the column. The flanges 98 on the half-column section are held by bolts 100 to corresponding flanges 102 on the beam form end 92, to encircle the column region and connect it to the region which is to form the beam in the-foor. Typically, the column 94 has already been formed to a height slightly above the bottom of the beam form 90, and the end 92 of the beam form and the half-column section 96 are mounted about this already-formed column portion. As with other joints, tape strips are applied to seal the joints against leakage.

A concrete floor with integral beams is constructed by first setting up shoring as shown at 110 in FIG. 2, to support the beam forms and plywood decks. The shoring may include pipes 112 with plates 114 at their upper ends, and wooden beams 116 that support the deck 16 and beam form 10 in position. The wooden beams 116 are generally placed so that they support the flanges and bottom walls of the beam forms. After the shoring has been installed, the deck 16 may be constructed, with gaps left in it for receiving the beam form. The beam form 10 is then lowered into position until it rests on the wooden beams 116 which have been set up to hold it. The

rods

48, 50 are then installed and the strap 42 is laid on them. Strips of tape 118 are then applied to seal the gap between the flanges and the deck. After the deck and forms have been thus installed, and reinforcing bars have been positioned over the deck and in the forms, concrete is poured above the deck and forms. When the concrete has set, the

rods

48, 50 are removed, the shoring is removed, the decks 16 are removed, and the form 10 is removed. The removal of the form 10 can be accomplished by driving wedges between the ceiling of the concrete floor 14 and the upper surface of the

flanges

26, 28, while pulling down on the beam form. Handling braces 120 can be provided to serve as grasping positions that aid in pulling down the beam forms as well as in otherwise handling the forms, and also serve to strengthen the forms. The handling braces are beams of wood attached to the plywood sheets at the sides of the forms, and are spaced at intervals of several feet along the length of the forms. 7

Thus, the invention provides beam forms which can be rapidly installed and removed, and which produce concrete structures with less noticable inregularities such as patchings. A limited number of form sizes can be utilized in constructing a building with concrete beams of a large variety of lengths, by the use of adjustment sections that permit small changes in beam length to be made using beam forms of a particular length. The adjustment sections can be constructed for functions other than merely joining two aligned beams, such as in joining four beams together at an intersection. The beam forms can have a tapered or inclined end to facilitate removal and one end can be constructed to form part of a column. The beam forms are utilized in methods that permit rapid installation and removal of the form by simplifying apparatus that holds the form sides against spreading. This simplification involves the use of straps positioned at the level of the floor, the use of rods that project through the ceiling to hold the straps, and the fact that the straps are left in the concrete.

FIGS. 7, 8 and 9 illustrate another embodiment of a beam form, which is constructed with resilient side walls that are designed to be deformed slightly by the weight of concrete in them. This resilient deformation is utilized to facilitate removal of the form from set concrete. The form 120' has a bottom wall 122,

side walls

124, 126 and

flanges

128, 130. The

side walls

124, 126 are constructed of a resilient material such as fiberglass and of a thickness which results in appreciable deformation when the form is filled with concrete. The deformation results in the lower portion of the side walls bulging out to the configuration shown in FIG. 8, under the pressure of the concrete. I

Initially, the

flanges

128, 130 are held against spreading by the straps 132 and bolts 134. However, after the concrete sets and the bolts are removed, the flanges and form sides are free to spread out. As shown in FIG. 9, the

sides

124, 1 26 spread out until they substantially achieve their original straight configuration. The bulge in the concrete near the lower part of the beam causes the sides to spread out, while the flexibility at the

corners

136, 138 allows considerable spreading to occur. The form 120' is then much easier to remove from the beam. It may be necessary to apply wedges or the like to the form to free sides so they can spring out to the configuration of FIG. 9, but the effort is less than is generally otherwise required. It may be noted that the bottom wall 122 does not have to deflect, and it can be stiffened by employing an increased thickness or by plywood bracing sheets or the like to prevent deformation.

The bulge in the beam is not greatly apparent since it is smooth and regular. For a fourteen inch wide beam that is 30 inches high, and covered by a six inch thick floor, the width W at the region of greatest bulge may be only about inches, or about 7 percent greater than the width before form deformation. [n the types of beams commonly used in concrete construction, a form construction which results in an increased width of at least a few percent will urge the sides to spread by at least a few degrees from their original position (which they have prior to pouring of concrete). The resulting tendency of the side walls to spread out will generally significantly reduce the effort required to remove the form. Of course, a variety of materials can be employed to construct the form besides fiberglass, so long as the form sides are resilient and will deform substantially when concrete is poured into them. It is also desirable that the lower corners, such as 136, 138 be flexible, although the necessary deflection can occur even if the corners are stiff. For beams of the type which have substantially parallel sides, the difficulty of form removal is especially great, and the resiliently deformable form is especially useful. However, this form construction is also useful for beams with angled sides illustrated in FIG. 2.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art and, consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

What is claimed is:

1. Apparatus for forming concrete structures including regions forming integral'beams, floors, and columns comprising:

an elongated beam form with a bottom wall and side walls extending in a generally upward direction from said bottom wall, the side walls at one end of said form extending along the surface of an imaginary cylinder of predetermined diameter up to locations on diametrically opposite sides of the cylinder, and said side walls have outwardly extending flanges at their extreme ends; and

a column form for joining to said outwardly extending side wall ends of said beam form to enclose the rest of said column region, to provide continuous beam and column regions, said column form extending along the surface of an imaginary cylinder of said predetermined diameter, and said column form having outwardly extending flanges for joining to the flanges on said beam form side walls.

Claims

1. Apparatus for forming concrete structures including regions forming integral beams, floors, and columns comprising: an elongated beam form with a bottom walL and side walls extending in a generally upward direction from said bottom wall, the side walls at one end of said form extending along the surface of an imaginary cylinder of predetermined diameter up to locations on diametrically opposite sides of the cylinder, and said side walls have outwardly extending flanges at their extreme ends; and a column form for joining to said outwardly extending side wall ends of said beam form to enclose the rest of said column region, to provide continuous beam and column regions, said column form extending 180* along the surface of an imaginary cylinder of said predetermined diameter, and said column form having outwardly extending flanges for joining to the flanges on said beam form side walls.