CA1040453A - Stirrup fabric and method for forming pipe reinforcement - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A cage assembly for reinforcing concrete pipe. In the production of concrete pipe, wire fabric cages are formed and concrete is cast around the cages. The wire fabric con-ventionally comprises a plurality of crisscrossed strands, those strands running one way defining the longitudinal strands of the formed cage and those running the other way define the circum-ferential strands of the cage. To reinforce the concrete pipe at the crown and invert regions thereof, stirrup members are welded to these portions of the cage. The stirrup members pro-ject radially outwardly from the cage and may be rigidly connected both to an inner cage and to an outer cage. While the use of stirrups as presently employed ultimately renders the concrete pipe considerably stronger and more reliable, their use is both cumbersome and costly so far as assembly of the stirrups on the rolled cages. The present invention provides a cage assembly which is more easily assembled and therefore less costly. The cage assembly comprises a cage body having a plurality of longi-tudinal and circumferential strands, and a pair of mats, each formed of a network of interconnected strands. One of the mats is located generally at the crown and the other located generally at the invert of the cage body. Each of the mats includes a plurality of stirrup projections projecting from the surface thereof and projecting outwardly from the surface of the cage body.

Description

104~)453 This application is a divisional of Canadian Application Serial No. 178,773 filed August 14, 1973.
This invention relates to fabric for reinforcing concrete pipe or the like. In the production of concrete pipe, wire fabric cages are formed and concrete is cast around the cages. The wire fabric conventionally comprises a plurality of crisscrossed strands, those strands running one way defining the longitudinal strands of ~, a formed cage and those strands running the other way defining the circumferential strands of the cage. Typically, cages are formed by passing the fabric through forming rollers.
It is common to further reinforce concrete pipe at the crown and invert regions thereof by welding stirrup members to these portions of the cage. Such stirrup members project radially outward-ly from the cage. They may be rigidly connected both to an inner cage and to an outer cage. The stirrups may be individual stirrups which are welded to either an inner or outer cage, or both, or they may comprise a continuous sinusoidal-shaped strand of wire.
Present industry practice involves first taking a flat sheet of fabric and passing it through rollers to form a generally circular or elliptical cage. The ends of the rolled cage are weld-ed together. Stirrup members are then welded to the cage, or fasten-ed between inner and outer cages, as described above.
While the employment of stirrups renders the ultimate con-; crete pipe considerably stronger and more reliable, it is both cum-bersome and costly for the concrete pipe fabricator to assemble the stirrups to the rolled cages.
In accordance with one embodiment of the present invention, ~; a fabric mat for reinforcing concrete pipe or the like comprises: a plurality of elongated stirrup members each defining a plurality of stirrup projections, joining means joining said stirrup members at spaced intervals, said stirrup members heing generally parallel to one another.
In accordance with a further embodiment of the present invention, there is provided a cage assembly for reinforcing con-. 9~

- 104~)453 crete pipe, said cage assembly comprising: a cage body having a plurality of longitudinal and circumferential strands, and a pair of mats, each formed of a network of interconnected strands. One of said mats is located generally at the crown and the other located generally at the invert of the cage body. Each of the mats includes a plurality of stirrup projections projecting from the surface thereof and projecting outwardly from the surface of the cage body.
Fabric of this nature can either be used for forming cages per se, or for integral reinforcing mats used as components in an overall cage assembly or used in other reinforcinq applications.
By securing the hinged stirrups to the fabric in spaced groups,one has a fabric which can be cut and formed into a cage with one group of hinged stirrups located at the crown of the cage and another group located at the invert of the cage. The concrete pipe manu-facturer has then merely to erect the various stirrup mem~ers at the crown and invert and pour concrete around the cage. In the al-ternative, the stirrup members can be arranged at regular intervals along the length of the fabric and the fabric can be cut into mats.
Once a cage is cut and formed from conventional fabric, one stir-rup mat can be joined to the cage at the crown thereof and the other can be joined to the cage at the invert thereof. Either meth-od of employing the fabric effects a substantial savings in cost to the concrete pipe manufacturer.
In the drawings which illustrate the embodiments of the present invention:
Figure 1 is a perspective view of a portion of a first embodlment hinged stirrup fabric made in accordance with the present invention, Figure 2 is a cross-sectional view taken along plane II-II of Figure L:
Figure 3 is a fragmentary cross-sectional view taken generally along planes III-III of Figure 1, Figure 4 is a fragmentary top plan view of the fabric shown in Figure 1, ~ : `

104~4S3 Figure 5 is a perspective view of a second alternative embodiment fabric embodying the present invention:
' Figure 6 is a perspective view of a third alterna-tive embodiment fabric embodying the pre-`. sent invention, Figure 7 is a cross-sectional view taken generally along plane VII-VII of Figure 6, Figure 8 is a fragmentary cross-sectional view 10 . taken generally along plane VIII-VIII of - Figure 6;
Figure 9 is a fragmentary perspective view of a first type of bayonet clip hinge, Figure 10 is a fragmentary perspective view of a second type of bayonet clip hinge:
Figure 11 is a perspective view of a third type ' of bayonet clip hinge;
; Figure 12 is a perspective view of a portion of a fourth alternative-embodiment fabric em-'~ 20 bodying the present invention, Figure 13 is a perspective view of a portion of : .
a fifth alternative embodiment fabric em-bodying the present invention, Figure 14 is an enlarged view of the tie rod of ~-, ; the hinged stirrup member of the fabric shown in Figure 13 showing the crimped portion of . the tie rod member, ; Figure 15 is a fragmentary cross-sectional view taken along plane XV-XV of Figure 13;
Figure 16 is a fragmentary cross-sectional view taken : along plane XVI-XVI of Figure 13, Figure 17 is a schematic cross-sectional view of a concrete pipe reinforced with fabric of the ~ 104()453 present invention, Figure 18 is a schematic cross-sectional view of the , concrete pipe reinforced with the fabric . of the present invention, and - ; Figure 19 is a schematic cross-sectional view of ;~ concrete pipe reinforced with fabric of ; the present invention.

In all of the alternative embodiments disclosed here-in, the fabric 1 comprises a plurality of elongated stirrup mem-bers 10, each defining a plurality of stirrup projections 11,hingedly joined to the fabric 1 by hinges 20 (Figs. 1, 5, 6, 12 !: and 13). The elongated stirrup members 10 can be collapsed so , as to lie generally coextensive with fabric 1, or they can be ;~ erected to a position with their projections 11 prajecting out-wardly from the surface of fabric 1. Fabric 1 can be cut into mats 5 for positioning at the crown and invert of a conventional el-liptical cage body 4 as shown in Fig. 17, or for positioning at ~; the crown and invert of an inner cage 6 and at the sides of an outer cage 7 as shown in Figure 19. In the alternative, elongated stirrup members 10 can be joined to fabric 1 in groups, the groups :, : .
~ being spaced from one another so that the fabric can be cut to ; . .
width and formed into a cage with the stirrups collapsed. One group ~ f stirrups 10 will be positioned at the crown and the other ;, ; at the invert (Fig. 18). Once the cage is formed, stirrups 10 are erected and concrete is cast around the cage.
In all embodiments, fabric 1 includes a plurality of longitudinal defining steel wires 2 welded to a plurality cir-cumferential defining wires 3 at right angles. When a cage is formed, wires 2 will run the length thereof and wires 3 will define the circumference thereof.

In the embodiment shown in Fig. 1, each elongated stir-rup member 10 comprises a segment of sinusoidally formed wire 40 joined to a tie rod 30 (Fig.l). Sinusoidal wire 40 and tie rod 30 are both made of steel wire. Various ones of the bottom nodes 41 of sinusoidal wire 40 are joined to tie rod 30 by means of welding or the like. It is not absolutely essential that all of the bottom nodes 41 be rigidly secured to tie rods 30. Bottom nodes 41 hook under circumferential defining wires 3 of fabric 1 and lie generally in a plane parallel to the longitudinal de-fining strands 2 of fabric 1. It is not essential that the spac-ing of bottom nodes 41 be identical to the spacing of circumfer-ential defining strands 3, it being conceivable that certain ones of bottom nodes 41 might not have to pass beneath a given cir-cumferential defining strand 3.
Tie rod 30 is hingedly mounted to a hinge rod 23 by means of hinges 20. Hinge rod 23, in turn, is welded to at least two circumferential defining strands 3 of fabric 1. Each hinge 20 comprises a hinge channel 21 joined to an attachment channel 22 (Figs. 2 and 3). Attachment channel 22 is secured to hinge rod 23, hinge rod 23 having a sqaure cross section and attachment channel 22 having a matching configuration. Preferably, attach-ment channel 22 is welded to hinge rod 23. Hinge channel 21 is adapted to receive tie rod 30.
Tie rod 30 is generally square in cross section. Hinge channel 21 of hinge 20 has a similar configuration, the opposite vertical walls of hinge channel 21 being generally flat. As a result of this construction, stirrup member 10 is firmly held in either its erected or collapsed positions. Hinge 20 is made of a material sufficiently flexible that as stirrup member 10 is rotated between its collapsed and erected positions, the opposite vertical walls of hinge channel 21 are free to flex outwardly slightly and to close back into their normal position as stirrup member 10 reaches its erected or collapsed position.
.. .
Tie rod 30 includes a deviation 31 therein for each hinge 20 (Figs. 2, 3 and 4). Deviation 31 is received within :- _ 1~41~)4S3 hinge channel 21 of hinge 20. Deviation 31 deviates from the -, axis of tie rod 30 a distance approximately equal to the thickness of sinusoidal strand 40. The deviation 31 makes it possible for all of hinge 20, including hinge channel 21, to lie generally in the plane of the longitudinal defining strands of fabric 1. Be-~; cause of deviation 31, stirrup member 10 can be opened to its erected position with bottom nodes 41 of sinusoidal strand 40 ; being positioned generally in the plane of longitudinal defining strands 2, and tie rod 30 being positioned below bottom nodes 41 except for the upwardly deviating deviations 31 which lie in hinge channels 21. Yet, when stirrup member 10 is collapsed, all of tie rod 30 and the bottom portions of sinusoidal strand 40 lie generally in the same plane as longitudinal defining strands The upper portions of projections 11 of sinusoidal strand 40 must lie outside of the plane of longitudinal defining strands 2 when stirrup member 10 is collapsed since they are sufficiently tall that they must lie on top of one or more adjacent longitudinal defining strands 2. Accordingly, each projection 11 includes a deviating portion 42 therein which causes the upper portions of projections 11 to lie generally in the same plane -as the circumferential defining strands 3 of fabric 1 when stir-rup members 10 are collapsed (compare Figs. 2 and 3). In this manner, the entire stirrup member 10 and its attendant hinges 20 are generally coextensive with fabric 1 when collapsed. This makes it possible to pass fabric 1, including stirrup members 10, through a set of forming rollers without causing damage to or hang-ups in the forming rollers as a result of projections from the surface of fabric 1.
The alternative embodiment fabric shown in Fig. 5 is identical to that shown in Fig. 1, except for the fact that the hinge rods 23 have been eliminated. Instead, attachment channels .

1~404S3 22 of hinges 20 are secured directly to a longitudinal defining strand 2 of fabric 1. In all other respects, the construction of the two alternative ~abrics is identical.
^ In the alternative embodlment fabric shown in Fig. 6, a sinusoidal wire 50 having a generally square cross section is substituted for sinusoidal wire 40. Both tie rod 30 and hinge rod 23 are eliminated. Instead, a bottom node 51 of sinusoidal strand 50 is carried in hinge channel 21 of hinge 20. Attachment channel 22 is attached directly to a longitudinal defining strand

2. Because sinusoidal strand 50 is generally square in cross section, it is firmly held in either its erected or collapsed position by its interaction with the similarly shaped hinge channel 21. Rotating sinusoidal strand 50 between its two posi-tions tends to spread the opposite walls of hinge channel 21 slightly apart and allows them to close back together when sinu-soidal strand 50 reaches its collapsed or erected position.
As with sinusoidal strand 40 described above, sinusoi-dal strand S0 includes a deviating portion 52 to allow the upper portions of projections 11 to lie on top of adjacent longitudinal defining strands 2, in a plane generally parallel to circumferen-tial defining strands 3. The bottom portions and bottom nodes 51, on the other hand, lie generally in the plane of longitudinal defining strands 2 when sinusoidal strand 50 is collapsed (com-pare Figs. 7 and 8).
The alternative embodlment shown in Fig. 6 could be modified by employing sinusoidal strand 40, having a generally ., .
circular cross section, in place of sinusoidal strand 40, having a generally square cross section, but in conjunction with a bay-,.,....... : .
~ onet-type hinge rather than in conjunction with the particular :, . , hinge 20 disclosed in Fig. 6. Three such bayonet-type hinges 90, 100 and 110 are shown in Figs. 9, 10 and 11, respectively.

Bayonet hinge 90 comprises a channel 91 with a mounting flange .

104~453 92 projecting at least from one side thereof. Mounting flange 92 is welded to a longitudinal defining strand 2. There may also be a mounting flange 92a on the opposite side of channel 91 posi-tioned generally beneath a circumferential defining strand 3.
The bottom node 41 of sinusoidal strand 40 passes beneath cir-; cumferential strand 3 and is positioned within channel 91. Bottom node 41 is sufficiently long in arc that sinusoidal strand 40 can be slid back and forth either in the direction of arrow A
or arrow B. Bayonet hinge 90 includes a stop flange 93 extend-ing upwardly from that wall of channel 91 which is opposite mount-ing flange 92. When sinusoidal strand 40 is in its erected posi-tion as shown in Fig. 9, stop flange 93 prevents sinusoidal strand 40 from being rotated downwardly to its collapsed position. In order to collapse sinusoidal strand 40, it is first slid in the direction of arrow B such that it is out of the way of stop flange 93 and is then rotated downwardly to its collapsed position.
Bayonet hinge 100 is similar in construction, (Fig. 10), including a channel 101, a mounting flange 102 and a stop flange 103, all of which operate the same as channel 91, mounting flange 92 and stop flange 93 of bayonet hinge 90. In addition, bayonet hinge 100 includes a lock flange 104 projecting upwardly from the bottom of channel 101. In order to erect sinusoidal strand 40, it is rotated upwardly and slid in the direction of arrow A. Then it is slid in the direction of arrow C, into position behind lock flange 104. In this position, it is not possible to slide sinu-~ soidal strand 40 back in the direction of arrow B. To collapse - sinusoidal strand 40, it must first be slid in the direction of arrow D, then slid in the direction of arrow B and then rotated downwardly to its collapsed position.
Bayonet hinge 110 (Fig. 11) is very similar to bayonet hinge 100. It includes a channel 101, a mounting ~lange 102, a stop flange 103, and a lock flange 104. The only difference in :

104(~453 construction from bayonet hinge 100 is that lock flange 104 ex-tends outwardly from the sidewall of channel 101 which is adjac-- ent mounting flange 102. The manner in which sinusoidal strand 40 is erected and collapsed in bayonet hinge 110 is identical to the manner in which it is erected and collapsed in bayonet hinge :.~, 100.
The alternative embodiment fabric shown in Fig. 12 is quite similar to that shown in Fig. 5, with the exception of the fact that individual Z-shaped projection rods 60 are sub-stituted for a continuous, sinusoidal strand 40. Each upwardly projecting Z-shaped rod 60 is welded to tie rod 30. Tie rod 30 in turn is mounted in hinge channel 21 of hinge 20 and hinge 20 is in turn attached to an adjacent longitudinal defining strand 2. Each Z-shaped projection rod 60 includes a book 61 at the top thereof to provide an additional anchor when a cage made from fabric 1 is embedded in concrete. ~he bottom o~ each rod 60 hooks under a circumferential defining strand 3 at 62 in order to provide a firm anchor for each circumferential defining strand

3.
In the alternative embodiment shown in Fig. 13, each stirrup member 10 comprises a straight, elongated tie rod 70 to which are welded a plurality of straight projection rods 80. Be-cause projection rods 80 do not hook beneath any circumferential defining strands 3, tie rod 70 can lie directly beneath circum-ferential defining strands 3-and entirely within the plane of longitudinal defining strands 2 without any deviations therein.
Projection rods 80 are welded to one side of tie rod 70, speci-fically to the side opposite the direction in which stirrup mem-ber 10 is rotated in order to collapse it. Because of this con-nection, tie rods 70 lie directly on top of any adjacent longi-tudinal definlng strands 2 and still lie in the same plane as circumferential defining strands 3 when stirrup member 10 is collapsed (compare Figs. 15 and 16).
Because tie rod 70 is generally round in cross-section-al configuration, it is crimped at those points along its length which correspond to the locations of hinges 20. This crimping creates a pair of flat surfaces 71 in tie rod 70 (Fig. 14). When stirrup member 10 is erected (Fig. 15) flats 71 cooperate with the flat bottom and flat side of hinge channel 21 to firmly hold stir-rup member 10 in its erected position. When stirrup member 10 is collapsed (Fig. 16) flats 71 cooperate with the bottom wall and opposite sidewall of hinge channel 2L to firmly hold stirrup mem-ber 10 in its collapsed position.
In Fig. 17, a concrete pipe has been constructed em-ploying an elliptical cage 4 made of conventional fabric in con-junction with a pair of stirrup mats cut from fabric made in accord-ance with the present invention. In constructing elliptical cage

4, conventional fabric is first cut, formed and welded at its free ends. Then, the hinged stirrup members 10 of stirrup mats 5 (stir-rup mats 5 being cut from fabric 1) are rotated to their erected position, and are inserted through thé openings in cage 4. Stir-rup mats 5 are positively secured to cage 4 by means of weldingat a few points, or by some other fastening means. The resulting cage assembly is placed in a pipe manufacturing machine and con-- crete is cast therearound.
Fig. 18 shows a concrete pipe in which stirrup members 10 have been hingedly joined to fabric 1 in groups, each group being spaced from the other a predetermined distance. The fabric 1 is then cut, formed into a cage 8 and welded as would be con-~; ventional. One group of hinged stirrup members 10 are located at the crown of the pipe and a second group of hinged stirrup members 10 are located at the invert of the pipe. A workman mere-ly erects the various hinged stirrup members 10, places cage 8 in a pipe making machine, and casts concrete therearound.

1~40453 Naturally, the distance between adjacent groups of hinged stir-rup members 10 varies in accordance with the diameter or configur~
ation which cage 8 is to have.
Figure 19 shows yet another pipe made in accordance with the present invention in which a conventional inner cage 6 and outer cage 7 are first formed. A stirrup mat 5 is posi-tioned at the crown and invert of inner cage 6 in the same manner as described in conjunction with cage 4 shown in Fig. 17. A
stirrup mat 5 is positioned at each side of outer cage 7 with 10 the projections 11 of individual stirrup members 10 projecting through outer cage 7 from the outside to the inside. The two cages 6 and 7 are arranged in concentric fashion within a pipe making machine and concrete is cast therearound.
As a result of the above invention, the laborious on-the-job securing of individual stirrup members or of individual sinusoidal stirrup segments to a formed pipe reinforcing cage is eliminated. When stirrup mats 5 are used, an entire group of stirrups are secured to the crown or invert of a cage in a single operation. Surprisingly, fabrlc 1 made in accordance with the , 20 present invention can be formed in conventional forming rollers.
Fabric 1 will readily roll through and form in such rollers with stirrup members 10 in their collapsed positions.
; Accordingly, the present invention represents a signi-ficant time and labor-saving contribution to the art. Of course, it is understood that the above are merely preferred alternative embodiments of the invention, and that various modifications and alterations can be made of these embodiments without departing from the spirit and broader aspects of the invention.
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Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A cage assembly for reinforcing concrete pipe or the like comprising: a cage body having a plurality of longitudinal and circumferential strands; a pair of mats each formed of a network of interconnected strands, located generally in said cage body in areas in which additional reinforcement is desired, each said mat including a plurality of elongated stirrup members, each stirrup member defining a plurality of stirrup projections projecting from a surface of each mat, and joining means joining said stirrup members at spaced intervals, said stirrup members being generally parallel to one another, the stirrup projections projecting outwardly from a surface of the cage body, hinge means hingedly join each of said stirrup members to said joining means of said mats.

2. The cage assembly of claim 1, in which said joining means of said mats comprise a plurality of strands extending generally laterally of said stirrup members.