CA1139122A - Locator for vertical reinforcing bars - Google Patents

Abstract

ABSTRACT
A fixture is disclosed for precisely locating the vertical reinforcing steel bars in a hollow block wall at the exact positions specified by the design engineer. The fixture comprises one or more steel wires forming a horizontal supporting structure that is adapted to be laid on the top surface of the blocks at various levels as the blocks are being laid. The horizontal supporting structure is a generally square structure having a circular ring attached to the inside of each corner and downwardly projecting legs that extend down into the cavities of the hollow blocks and engage the inner surfaces thereof to locate the structure with respect to the blocks. The rings of the structures at different levels are positioned in vertical alignment with respect to one another, and the vertical bars are lowered into the block cavities from the top of the wall, with the bar being inserted through each of the rings, in turn, at the different levels. After the steel bars have been placed, the cavities are filled with cement grout, which embeds the bars.

Description

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Ihis is a division of Canadian Application Serial No. 342,809 filed December 31, 1979.

BACKGROUND OF THE INVENTION
The presen-t invention pertains to steel reinforcemcn~
used in concrete block construction, and more particularly to a device for positioning vertical steel reinforcement bars precisely where they are designed to be located, so that the full tensile strength of the steel bar is utilized, as intended by the engineer who designs the wall.
Concrete blocks and mortar have relatively little tensile strength, and it is therefore necessary to use steel reinforcing bars to provide the necessary -tensile strength, some of the bars extending vertically through the cavities in the blocks, so as to anchor the blocks to the concrete footing, and some extending hori~ontally along the mortar joints at various levels.
'rhe vertical bars are particularly important, as they provide most of the tensile strength to prevent the wall from failing under horizontal pressure, such as the pressure exerted by soil on one side of the wall~ For most economical design, the engineer locates the bar as far as possible from the neutral axis of the wall toward the tension side of the wall, while still allowing a certain minimum amount of space between the bar and the inner surface of the block cavity to allow concrete grout to flow around the bar so as to completely embed it. I'his is done by specifying a distance "d" from the outer surface of the block on the compression side of the wall to the center of the vertical steel bar. The larger the distance "d", the smaller the required steel area. If the actual "d" is smaller than the design "d", then the actual stress on the steel will be greater than the calculated stress, with the consequent potential for overstressing the steel.
In practice, it is difficult, and in fact, almost impossible to keep the vertical rein~orcing bar at the precise lstance "d" relative to the outer surface of the blocks from the top of the wall to its bottom as the grout is being poured.
As a result, the bar may dri~t or bend away from the inner surface of the block toward the neutral axis of the wall, where the bar is subject to being overstressed. To compensate for uncertainty as to the actua] distance "d", design engineers customarily use only 50% of the tensile strength of the steel in their calculations if there is not to be continual inspection of the steel on the job. This results in the use of oversize steel bars. Even when oversize steel reinforcing bars are specified, there is some danger that the bars may become dis-placed far enough from their design location to make them relatively ineffective, resulting in overstress in the masonry.
Specifying oversize reinforcing bars is e~pensive, and adds greatly to the cost of the wall~

SUMMARY OF THE INVEN~ION
The primary object of the presen-t invention is to provide means for positively locating vertical reinforcing bars at the precise position called for in the specification, thereby ` assuring the design engineer that the bar will remain at its intended location at all times, and its full tensile strength will be utilized. This ob~ect is achieved by means of locating assemblies that are placed in the horizontal mortar joints of the wall at specified levels as the wall is built, the said assembly being formed from steel wires shaped to coincide with portions of the blocks, having downwardly projecting locator pins that engage the blocks to position the assembly in the desired location and also having circular rings formed therein, through which the vertical reinforcing bars are passed.
Among the advantageous features of this arrangement are~ it is easy to use, and saves time and money; (2) no special skill is required. The assembly is merely placed on the mortar joint, and locator pins position the assembly in the sd/~ 2-~L39~

correct position; (3) the vertical reinforcin~ bars are fixedly held in -the desired location and cannot move either longitudinally or transversely with respect to the wall; (4) the added steel of the ladder reduces the amount of steel reinforcement required;
and (5) it allows the design engineer to use the full allowable stress for the steel reinforcement bar, as he can be confident that the bars will remain at the exact position specified and will not drift to a position where they would be subject to overstressing.
The invention as defined in the parent application achieves these advantages by providing a fixture for use in masonry construction utilizing hollow blocks having two longitudinally spaced cavities separated by a transverse web, wherein vertical reinforcing bars must be precisely located within a cavity that is subsequently filled with cement grout the fixture comprising: a horizontal supporting structure that is adapted to be p].aced on the top surEaces of the ~locks at various levels of the masonry construction as the blocks are being laid, the supporting structure consisting of a ladder-like unit formed with laterally spaced, parallel wires that are connected together at intervals by cross-wires; the horizontal supporting structure having a plurality of rings provided thereon at locations where the reinforcing bars are to be located, the rings of the supporting structures at different levels of the masonry construction being vertically aligned with respect to one another so as to receive the vertical reinforcing bars when the latter are passed downwardly into the cavity and through the rings from the top of the completed or partially completed construction; and certain of the cross wires having cross 3n pieces attached thereto, the cross pieces terminating in down-wardly bent legs that are adapted to straddle the transverse webs of the blocks.

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On the other hand, the invention accordin~ to this divisional application achieves the aforementioned advantages by providing a fixture for use in masonry construction utilizing hollow blocks which, in the completed construction, form a generally square cavity, and in which ~
vertical reinforcing bars must be precisely located within the cavity that is subsequently filled with cement grout, the fixture comprising: a horizontal supporting structure that is adapted to be placed on the top surfaces of the blocks at various levels of the masonry construction as the blocks are being laid, the supporting structure comprising wire bent into a square; a plurality of rings attached to the insi.de of the four corners of the square, the rings of the supporting structure at different levels of the masonry construction being vertically aligned with respect to one another so as to receive the vertical reinforcing rods when the latter are passed downwardly into the cavity and through the rings from the top of the completed or partially completed construction;
and legs at the corners of the square that are adapted to engage the inside corners of the square cavity to center the supporting structure within the cavity.

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B~IEF DESC~IPTION OF THE Dl~AWINGS

Figure 1 is a perspectiye view of a course of hollow concre1:e blocks, showing the device of the inven-tion placed on a mortar joint, and with one vertical rein-forcing bar inserted through a ring in the device;
Figure 2 is ~n enlarged cross-sectional view taken at 2- 2 in Figure l;
Figure 3 is a fragmentary sectional view taken . at 3--3 in Figure l;
Figure 4 is a perspective view of a slightly differ-ent orm of the .invention setting on a mortar joint of a course of blocks, this embodiment being used where two verti-cal reinorcing bars are arranged side-by-side, as when the bottom courses o~ a wall are o extra wide blocks, while the upper courses are of noxmal width blocks;
Figure S is a view showing an end view of a wall ~o~tructed as descrlbed above;

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Figure 6 is a perspective view of a short length of still anothe~ em-bodiment of the invention;
Figure 7 is a perspective view of a square co1~Lrnn formed of blocks, or bricks, showing another form of the invention; and - Figure 8 is a perspective view of still another form of the invention, for use in building a square column as shown in Figure 7.
DESCRIPIION OF IHE PREFERRED EMBODIMEN~: -~ Figures 1-3 of the drawings, the reference nuIneral 10 designates a portion of a block wall, made up of a plurality o conventional hollow 10 concrete blocks 12, which are mortared together by end mortar joints 14 and horizontal ~nortar joints 16. In the drawings, the exposed top surface of the blocks is designated as a horizontal mortar joint, although no mor-tar has been applied as yet. Each of the blocks IZ has two side-by-side cavities 18 for~ed therein, which are separated by a transverse web 20.
Ihe device of the present invention i9 designated in its entirety by the reference numeral 22, and is seen to be generally 1adder-~ike in configur-ation, being made of two laterall~ spaced, parallel wires 24 and 26, which are joined together at intervals by transverse wires 28 and 3~. ~he wire is preferably about No. 8 gauge steel wire, althou~h other gausges may be 20 used, depending upon the strength requirements. For a nominal 8-inch block, which is actually 7-5/8 inches wide, wires 24, 26 would be spaced 6-1/8 inches apart, so that the wires each lie 3J4 inch from the outer edge of the block, so that if the mortar joint is raked, the wires will not be e~posed, In the case of a 12-inch block, which i9 actually 11-5J8inches wide, wires 24, 26 would be spaced 10-1/8 inches apart. For blocks of other width dimensions, the wires 24, 26 would be spaced apart 1-1/2 inches less than the actual width dimension.
Iransverse wires 28 are forn~ d with downwardly projecting legs 32 near each end thereof, which converge siightly, as best shown in Fig. Z.

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Legs 32 rn2~ bc forrr~ed hy bending the wire, as illustraled in the drawine, or by welding short lengths of wire to the crosspieces 28. 'rhe purpose of the legs 32 is to center the ladder-like wire fixture 22 in the middle of the line of blocks 12, and to this end, the legs 3Z are inserted down into the cavity 18, where they engage the iImer side wall surfaces of the blocks.
~he downward taper, or convergance, of the legs 32 facilitates insertion of the leg s down into~ the cavity, and when the device 22 is in place, the upper ends of the legs make contact with the cavity surface of the block, or lie very closely adjacent thereto, e. g. about 1/8-inch distance.
Closelyadjacent one of the legs 32, the cross wire 28 is coiled into a ` circular ring 34 having an inside diameter of approximately 3/4-inch, so that a 3/8, 1/2, or 518-inch steel reinforcing bar 36 can be pa93ed down through the center of the ring. In some cases, as for free-s~anding walls, it may be desirable to have the vertical steel reinforcing bars 36 centered within the block cavity 18, in which case the ring 34 would be formed at the midpoint of the wires 28.
Cross wires 30 have no circular rings, but instead are provided with locatexs 38, each consisting of a cross piece of wire 40 having a pair of downwardly turned legs 42 that straddle the center web 20 of the block, s o

2 o as to fixedly locate the ladder~like fixture 22 lengthwise alo~g the wall, Legs 42 also diverge downwardly to facilitate placing the legs down over the web 20.
~ he Uniform Building Code states that the vertical reinforcing bars 36 shall not be spaced more than 48 inches on center, but may be any lesser distance, such as 16, 24, 3Z or 48 inches. Rings 34 may therefore be spaced apart along the length of the ladder~ ;e fixture Z2, various hlcre-ments of distance which would l~ake it possible to space the vertical bars at 16, 24 32 or 48 inches on centers. Cross wires 30 with their locaters 38 would be spaced apart some multiple of the block length, so that the LZ~

!ec~s 4Z will always be positioned to straddle the center web of a respec-tive block.
One adv~ntage of the invention is that the ladder-like fixture Z2 can be t~rned 180 to place the vertical bars 36 near either the inner or outer surface of the wall. Thus, for a basement wall, the steel bars would be placed closer to the inside surface of the wall, whereas for a free-standing cantilevered retaining wall, the steel bars would be placed closer to the suxface of the waIl in contact with the s oil.
~ he devices 22 are preferably formed in 8'6" lengths, and are laid 10 with their ends overlapping 6 inches so that when the overlapped ends are embedded in grout, the ladder devices 22 form, in effect, a continuo ~ls length of steel, which allows the wires Z4, 26 to be figured as part o the horizontal steel reinforcing for the wall. Other hori7ontal steel reinforce-ment bars can therefore be correspondingly reduced in size. The devices 22 would be placed on the horizontal mortar joints at every 3rd or 4th course of blocks, according to the building code, with the rings 34 of each ladder aligned vertically with the rings of the ladders below. When the wall has been built to the desired height, vertical reinforcing bars 36 a~e inserted down through the rings 34, and the cavities CQntaining the 20 reinforcing bars are filled with grout.
'rhe rings 34 of the ladder-like devices 22 hold the reinforcing bars 36 precisely at the designed locations, and prevent the bars from being displaced while the grout is being poured and puddled. With the vertical reinforcing bars positively located at the exact location specified by the design engineer, the full strength of the bars is utilized, and the strength of the wall iF therefore assured. 'rhe rings 34 can be located wherever the desi~n engineer specifies that the vertical bars 36 are to be placed, and, if des;red, two rings can be provided side-by-side on cross wires 28, as in Fig. 6, one of which is to receive the stub steel bar that is embedded ~3~

in the concrete footing, and projects upwardly therefrom, ~vhiie the cther ring receives the vertical reinforcing bar that is lowered into the block cavit~ from the top of the wall. Alternatively, a single ring 34 might be provided at the midpoint of cross wires 28, or two side-by-side rings might be provided, as sho~,vn in Fig. 6. The rings 34 may be sp~ced apart longitudinally from one another by any desired distance to meet the engin-eer's design; or two rings can be provided on each cross wire 28, with ring located adjacent each face of the block cavity, as when double steel is required for heavily loaded walls; and the rings can be made with any 10 desired inside diameter to accept any particular size of reinforcing bar 36.
Masons who have tried the invention has found it easy to use, and approve of its use, as it saves time and money in locating the vertical reinforcing bars according to specifications. The ladder-like fixture 22 is merely dropped into plaFe on the mortar joint, and the legs 32 and 42 locate the device in the correct position. No special skill is required, and no time is w asted. ~he double strength legs 3Z are not easily bent out of shape, and are inclined approximately 15 f~om the vertical for ease of insertion.
A slightly modified form of the invention is shown in Fig. 4, where the 20 ladder-like fixture is designated by the reference n~neral 22'. This partic-ular embodiment is intended for use in the situation whe re the bottom three or four courses of blocks are made with lZ-inch blocks and the re-mainder with 8-inch blocks, as in Fig. 5. In this case, the bottom blocks are anchored to the concrete footing 35 b~r means of stub steel bars 36 ', the bottom ends of which are embedded in the concrete, and the top ends of which project upwardly from the surface of the footing for approximately the heigh~ of the bottom three or four coursesO As the blocks are laid, they are îowered over the top ends of the stub steel bars 36'. The devices 22' that are used with the bottonn three or four courses of wicle blocks, snd pa-iicularly at the junction of the narrower blocks with the wider blocks, are provided with a third longitudinal wire 44 which i9 disposed between and parallel to outer wires 24' and 26', ~Therever wire 44 crosses over the cross wires 28' and 30', it is welded to them to provide additional strength and rigidity to the ladder. Longitudinal wires 44 and 26' are spaced apart the saIne distance that wires 24 and Z6 are spaced for the ladders ~;ed in the upper courses of blocks. Ihus wire 44 is embedded in the transverse mortar joint between the top block of the wide blocks and the bottom block of the narrower blocks forming the upper portion of the 10 wall. Cross wires 28' have two circular rings 34' formed therein, which are located to position vertical reinforcing bars 36 and 36' at the correct position, as shown in Fig. 5.
Cross wire 28~ also has downwardly projecting legs 32 ' adajcent the outer wires Z9', 26', and cross wire 30' has a cross piece 40' with down-wardly projecting legs 42' at each end, which straddle the center web 20 of the block. .As in the preceding embodiment, the legs 32' and 4Z' are set at a 15 angle to facilitate placement of the ladder on the blocks.
Another forn~ of the invention is shown in Fig. 6, where the ladder-like fixture is designated by the referenee nume ral 22". In this case, the cross 20 wires Z8" have two rings 34" formed side-by-side, one of which receives .
a stub steel bar projecting upwardly from the concrete footing, and the other receiving a vertical reinforcing bar which is lowered into the block cavity from the top of the wall prior to being embedded in grout. Other-wise, the ladder fixture 22" is generally similar to fixture Z2 in Figs. 1-3.
Fig. 7 shows still another form of the invention, designed specifically to locate the vertical reinforcing bars in a ~;quare column 48 built up of column blocks 50. ~he blocks 50 are laid up, one on top of the other, forming a square cavity 52 in the center of the column. ~he fixture 46 is formed of wire 54 bent into a .square configuratioll, with hc>r;zontally out-~ ~.3g~

wardly projecting legs 56 at the mi'dpoints of the four sides of the square.Welded to the wire 54 on the insides of thc four corners are four circular rings 58. Also welded to the wire 54 at the four corners thereof are down-wardly projecting legs 60, which extend down into the cavity 52 to center the fixture 46 on the column. Rings 58 rnay be located anywhere along the length of the wire 54, as specified by the design engineer, and when ~he vertical steel reinforcing bars have been passed down through the rings, the'bars will be positively held in the exact position specified.
Still another form of the invention is shown in Fig. 8, where the fix-10 ture is designated by the reference numeral 62. Fi~ture 62 is also designed for use in a square column of the type shown in Fig. 7. Fixture 62 also comprises a wire 64 bent into a square, with circular rmgs 66 welded to the insides of the four corners, and upwardly projecting legs 68 also weld-ed to the corners. At their upper ends, the legs are bent horizontally out-ward at 70 to form fingers that rest on'the top edges of the blocks. ~he square wire fixture 64 is dropped into the cavity of the colu~nn, and legs 68 fit snugly into the corners of t~ cavity to center the fixture within the cavity. As in the preceding embodiments, rings 66 may be welded at any desired location along the length of the wire 64 to position the vertical 20 bars at the exact location specified by the engineer.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A fixture for use in masonry construction utilizing hollow blocks which, in the completed construction, form a generally square cavity, and in which vertical reinforcing bars must be precisely located within the cavity that is subsequently filled with cement grout, said fixture comprising;
a horizontal supporting structure that is adapted to be placed on the top surfaces of the blocks at various levels of the masonry construction as the blocks are being laid, said supporting structure comprising wire bent into a square;
a plurality of rings attached to the inside of the four corners of the square, said rings of the supporting structure at different levels of the masonry construction being vertically aligned with respect to other another so as to receive the vertical reinforcing rods when the latter are passed downwardly into the cavity and through the rings from the top of the completed or partially completed construction; and legs at the corners of the square that are adapted to engage the inside corners of the square cavity to center the supporting structure within the cavity.