US3195278A - Dual lag screw anchoring insert for a concrete slab - Google Patents

Description

Jilly 20, 1965 H. a. BALLOU mm. me SCREW ANCHORING msnnr FOR A CONCRETE SLAB Filed llay 7, 1962 2 Sheets-Sheet 1 liar 3 6- 6 li njj" July- 20, 1965 Filed May 7. 1962 H. a. BALLOU 3,195,278

DUAL LAG SCREW ANCHORING INSERT FOR A CONCRETE SLAB 2 Sheets-Sheet 2 Irzflrzfw: 17271} 6: [1064.

United States Patent ration of Delaware Filed May 7, 1962, Ser. No. 192,771 1 Claim. (Cl. 50-472) The improved anchoring insert comprising the present invention has been designed for use primarily in connection with concrete wall slabs of the tilt-up type wherein the insert which is formed for the most part of heavy wire or rod stock is adapted to be embedded in one corner portion of a wall slab during formation of the latter, and serves, with similar inserts in the other corner portions of the slab and after hardening of the concrete, as a medium whereby the slab may be detachably connected to a crane or like hoisting mechanism to the end that the slab may be first raised while in a horizontal position and then tilted into a vertical position next to a concrete floor slab in connection with the erection of a building. The invention is, however, not to be limited to such particular use, and a wire-formed insert which is constructed according to the principles of the present invention may find use wherever an anchor point is required in a concrete structure undergoing formation. Irrespective, however, of the particular use to which the invention may be put, the essential features thereof are at all times preserved.

As disclosed in United States Patent No. 2,794,336, granted on June 4, 1957, and entitled Lag Screw Anchoring Insert for a Concrete Slab, a dual lag screw anchoring insert of the general character with which the present invention is concerned includes as its principal components a pair of spaced apart, nut-like, wire-formed helices to which there is welded a wire supporting structure presenting a series of supporting legs whereby the helices are adapted to be supported from a foundation surface so that they assume elevated positions above such foundation surface, the entire assembly assuming the general form of a chair. When the slab or structure-forming concrete is poured, the chair-like insert becomes embedded in the concrete and the helices assume positions at right angles to the upper surface of the poured slab and with their upper ends substantially flush with said surface to the end that they may receive therein the shank portions of lag screws or other attaching devices. The present invention is designed as an improvement over the dual lag screw anchoring insert which is illustrated and described in the aforementioned patent in that it offers several advantages thereover.

When lifting stresses are applied to an anchoring insert of the type with which the present invention is concerned in order to raise the associated slab, there is a tendency for the insert to pull out of the concrete. This is particularly true where the concrete of the slab has not fully hardened or become set. Subsequently, when tilting operations are in progress whereby the slab is turned on edge and placed against a floor slab, considerable torque is developed and applied to the anchoring helices by the lag screws which are received therein, thus creating a tendency for the helices to become angularly displaced. For these reasons, the aforementioned wire-supporting structure which is associated with the helices invariably involves outrigger devices in the form of wire loops, transverse rods and other projecting parts which are welded to the helixes and to one another, extend in various directions and are calculated to establish the necessary reaction forces to prevent displacement of the helices from their fixed positions of embedment in the concrete slab. The dual lag screw anchoring insert of the present invention offers a more efficient arrangement of such outrigger devices than is present in connection with conventional anchoring inserts including the insert of aforementioned Patent No. 2,794,336, both against angular shifting of the helices and against upward or axial pulling of the helices through the slab. It also offers a structure which, when in position within the slab form preparatory to concrete pouring operations, offers a greater reaction area within the concrete while at the same time offering a definite economic advantage inasmuch as an appreciable portion of the insert is made up of scrap reinforcing rod Which is to be found in large quantity at the scene of any large scale building operation and, therefore, need not be furnished as a component part of the manufactured insert. Because of the fact that an appreciable portion of the insert is not a part of the manufactured item, less storage space is required for the inserts when shipped in quantity and freight charges are proportionately reduced.

Another advantage that accrues from the present invention resides in the fact that whereas with a conventional anchoring insert the supporting structure for the helices must be itself supported from the floor slab or other foundation surface so that in the completed slab there are portions of the structure which are exposed or nearly exposed at the surface of the slab, in the present insert the supporting structure, and consequently, the entire insert, may conveniently be supported in an elevated position above the foundation surface so that, after the slab is formed, the insert as a whole is disposed well within the confines of the slab and away from the top and bottom surfaces thereof. This advantage of the invention is made possible by a novel saddle arrangement which is inherent in the supporting structure for the helices and by which the supporting structure is itself supported on the reinforcing bars which ordinarily are associated with tiltup and other types of slabs.

The attainment of the above-outlined advantages of the present dual lag screw anchoring insert constitutes the principal objects of the present invention and other objects and advantages will readily suggest themselves as the following description ensues.

In the accompanying two sheets of drawings forming a part of this specification, one illustrative embodiment of the invention has been shown.

In these drawings:

FIG. 1 is a perspective view of a dual lag screw anchoring insert constructed in accordance with the principles of the present invention;

FIG. 2 is an enlarged fragmentary side elevational view of one side or section of the insert;

FIG. 3 is a top plan view of the structure shown in FIG. 2;

FIG. 4 is an end view of the structure shown in FIG. 2;

FIG. 5 is a fragmentary vertical sectional view taken through a tilt-up type concrete wall slab in the vicinity of two embedded anchoring inserts, showing the slab within a slab form and also showing, in dotted lines, the slab after it has been connected to a harness on a crane or overhead hoist; and

FIG. 6 is a fragmentary top plan view of a slab form showing a number of the anchoring inserts operatively installed therein prior to a concrete pouring operatic-n.

Referring now to the drawings in detail, the anchoring insert which is disclosed therein constitutes a preferred form or embodiment of the invention and is designated by the reference numeral 10. This insert is adapted, with similar inserts, to be embedded in a tilt-up type concrete wall slab such as the slab which is fragmentarily shown at 12 in FIG. 5 and to form with such inserts a medium whereby the slab may be detachably connected to a crane or other overhead hoist to the end that it may be raised, and then tilted into a vertical position next to a concrete 3 r g floor slab in connection with the construction of a concrete building.

Insofar as the actual handling of the slab is concerned,

1 various methods of raising the same and then tilting it are clurrently in use. For a better understanding of the present invention, reference may be had to aforementioned Patent No. 2,794,336 for one exemplary method of handling the slab. Briefly, and as generally described in such patent, the wall slab is formed by pouring wet or fresh concrete over the surface of a previously cast floor slab 14 and within a slab form consisting of form boards 15. A layer or film of nonadhesive material is applied to the top surface of the concrete floor slab'ld so that the concrete for the wall slab 12, when hardened, may readily be lifted from the floor slab for placement or positioning purposes. The floor slab 14- rests on a fill or foundation 16 at the site where the building is undergoing erection. Prior to pouring of the concrete to form the wall slab 12, the anchoring insert 19 and its associated similar inserts are placed over the hardened concrete of the floor slab 14, preferably at the corner regions thereof, and the concrete is then poured within the form to form the wall slab 112..

As will be described in greater detail hereafter, such positioning of the insertsover the floor slab 14, according to the present invention, is accomplished by supporting the inserts upon previously positioned reinforcing rods which are an attribute of conventional tilt-up slabs, so that the insert will lie well within the physical confines of the slab form and be appreciably removed from-surface exposure in the completed wall slab. When the inserts are in position within the wall form concrete is then poured within the form boards in order to form the wall slab 12. After the concrete has hardened and the form boards have been removed, the wall slab 12 with the anchoring inserts 1t embedded therein is in readiness to be raised and subsequently tilted into a vertical position next to the floor slab 14 as hereinafter described.

The anchoring insert 10 is of a composite nature but, nevertheless, it is a unitary structure and for the purpose of the following description, it will be considered as being embedded in one corner region of the wall slab 12 while the latter. is horizontally positioned over the concrete floor slab 14'. As its principal components, the insert 1%) comprises a pair of nut-like wire helices 3t and 31 and a supporting structure 32. The structure 32 is common to the two helices and is provided for the dual purpose of providing a reaction thrust against the tendency of the helices to work loose in the concrete bond after the concrete of the slab has been poured and has become hardened and when lifting thrust is applied to the lag screws which are threaded into the helices, and of supporting the helices in their elevated spaced apart positions within the slab form.

The supporting structure 32 is comprised of four wireforrned parts, namely, a pair of generally horizontally extending combined saddle and cradle parts 34 and 36, and a pair of wire-formed wing parts 38 and 4 The saddle and cradle parts 34 and 36 are common to and extend between the helices 3t and 31, while the wing parts 38 and 4t? are individual to the .helices 3t and 31, respectively.

The saddle and cradle parts 34 and 36 are similar in their construction and each is in the form of an elongated length of relatively heavy wire stock which is bent so as to provide an elongated and straight medial section 42, a

pair of upwardly presented, U-shaped cradle portions id, and a pair of vertical legs 46 at the outer sides of the -of the elongated dual lag screw anchoring insert 18.

A to receive loosely therein a pairof horizontally extending anchor bars 54 in a manner and for a purpose that will be made clear presently. The'two saddle and cradle parts 34 and 36 extend generally in parallelism longitudinally The outside vertical legs 46 are offset inwardly from the vertical planes of the medial, sections 42 so that the distance between adjacent vertical legs 46 is less than a helix diameter, while the distance betwen the two medial sections of the saddle and cradle parts 34 and as is greater than helix 30 at regions which are spaced fairly widely apart,

this arrangement being best illustrated in FIG-3.

The adjacent U-shaped cradle portions 44 of the saddle and cradle parts 34 and 36 lie in vertical planes which extend at an angle of approximately 60 to each other as shown in FIG. 3. The depth of these cradle portions is approximately equal to the vertical depthof the wing parts 38 and 44), which is to say that the lower parts of the cradle portions and wing parts all terminate in substantially the same horizontal plane. The triangular portions of the wing parts 34 and 36 lie in planes which are inclined outwardly and downwardly away from the vertical axes of the helices 3t) and 31at angles of approximately 30.

As shown in full lines in FIGS. 5 and 6 and as heretofore indicated, the dual lag screwanchoring insert 19 is adapted to be supported within one corner portion of a rectangular form which is defined by the form boards 15. The two horizontally extending medial sections 42 of the saddle and cradle parts. 34 and 36 are adapted to be supported upon adjacent parallelspaced apart rein forcing rods 52, such rods being shown in dotted lines in FIGS. 2 and 3 of the drawings and in full lines in FIG. 6. The distance between the vertical legs 50 at the ends of these medial sections 42 is slightly greater than the spacing of the reinforcing rods 52 so that the saddle-like central region of the insert 10 may seat upon the reinforcing. rods with but little end play longitudinally of the insert, and-so that ,by merely positioning the insert 10 on the rods 52, proper alignment of the insert will automatically take place. When thus in position on the rods 52, the lower ends of the cradle portions 44 .as well as the lower ends of the Wing parts 38 and 40 will be positioned a slight distance above the upper face 70 of the floor slab 14 which, in effect, constitutes the bottom wall of the form for the wall "slab 12. Stated otherwise, the entire insert 10 will be suspended an appreciable distance above the surface 70 so that in the finished wall slab 12, the insert 10 will be more or less centered between the upper and lower faces '72 and 74 of the wall slab.

It-will be understood that three other anchoring inserts 10 will be positioned in the form for ultimate embedment in three other corners of the wall slab 12.

After the insert it) is in position within the form as heretofore described, the anchor bars 54. are loosely positioned within the cradle portions 44 of the combined saddle and cradle parts 34 and 36,and when so positioned within said cradle portions, these anchor bars increase the effectiveness of the inserts. While'the manufacturer of the anchoring insert, may, if desired, furnish suitable anchor bars for use at the scene of operations, ordinarily such bars will not be furnished and the contractor or consumer may rely for these bars upon the existence of scrap reinforcing rods, of which'there invariably is a large quantity in and around theiscene of any large-scale building operation. The length of the anchor bars 54 is not critical, and bars of varying lengths which are suitable for use may be found at the scene of operations and placed within the cradle portions 44 without further attention. If suitable lengths are not available, it is a comparatively easy matter to saw an elongated length of the reinforcing rod stock to form the anchor bars. It is to be particularly noted that because of the location or position of the bottom parts of the cradle portions 44 with respect to the lower face 74 of the wall slab 12, there is a maximum amount of concrete above the anchor bars. As theresult of this, the insert is effetcively held in place in the wall seat and will not pull out even though the slab is raised while the concrete is in a green or partially set condition.

After the wet concrete for the wall slab 12 has been poured, suitable strickling operations utilizing a screed are performed upon the upper surface of the concrete in order to produce the fiat upper face 72. When the concrete of the wall slab 12 has become set to a suitable degree, the form boards 15 are removed, and in order that the wall slab 12 may be hoisted from its horizontal position on the floor slab 14 and then tilted into a vertical. position for Wall-forming purposes as previously described, lag screws such as have been shown at '75 in FIG. 5 are threaded into the helices and 31 and constitute media whereby the wall slab 12 may be detachably connected to a crane or other overhead hoist.

Still considering the wall slab 12 to be in its horizontal position on the floor slab 14 preparatory to hoisting operations, the lag screws pass through the then horizontal flange 7e of an elongated angle piece 78 and serve to clamp this angle piece hard against the upper face 72 of the wall slab 12. The vertical flange 80 of the angle piece is provided with a hole 82 therethrough and receives the shank portion of an eye bolt 84, the latter being operatively connected to one of the cables 86 of a hoisting harness in associated relation with the crane or other overhead hoist. The details of the hoisting harness have not been disclosed herein since the harness forms no part of the present invention. It is deemed sufficient to state that the cable 86 passes loosely over a sheave 88 and that the opposite ends of the cable 86 are connected in a manner previously described to another dual anchoring insert 10 in an opposite corner region of the slab 12.

The specific manner in which the slab 12 is first hoisted vertically from its horizontal position and then tilted into position against the floor slab 12 has been disclosed in the aforementioned Patent No. 2,794,336 and need not be described herein. However, for illustrative purposes, the dotted line disclosure of FIG. 5 shows the elevated slab immediately prior to the tilting process. It will be observed that when the stress upon the helices 30 and 31 is vertical, as, for example, during lifting of the slab 12 from the floor slab 14- upon which it is formed, the helices will find adequate support in the concrete on both sides thereof in the longitudinal direction of the insert. The spread of the wing parts 38 and 40 outwardly and downwardly in the corner regions of the slab 12 gives good support to the remote or outer sides of the two helices, while the two combined saddle and cradle parts 3 5 and 36, together with the anchor bars 54, afford good reaction for the helices at the inner or opposed sides thereof. As the slab is tilted preparatory to fitting the same against the floor slab in a vertical position, the lateral stresses which are applied to the two helices 3t) and 31 are assimilated in approximately equal degrees by the wing parts 38 and 40 and the combined saddle and cradle parts 34 and 36.

The invention is not to be understood as restricted to the details set forth since these may be modified within the scope of the appended claim without departing from the spirit and scope of the invention.

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

As a new article of manufacture, a dual lag screw anchoring insert adapted for initial positioning in a concrete slab form and ultimate embedment in the concrete slab, and adapted to form an anchor for a pair of lag screws, said insert comprising a pair of wire helices disposed in spaced apart relation and adapted to have their axes extend vertically with their upper ends disposed directly inwards of and opening onto the upper face of the slab when the latter is in the horizontal position in which it is cast, the interiors of said helices forming internal screw'threads for receiving the shank portions of the lag screws, and a supporting structure for said helices whereby the same may be supported in their spaced relation from a pair of adjacent parallel horizontally extending reinforcing rods pre-positioned in the form, said supporting structure including two spaced apart, generally parallel, lengths of wire stock, each length having an elongated horizontal medial section midway between the vertical axes of the helices and below the level of said helices and constituting a major portion of the length, and downwardly extending bight portions at the opposite ends of the medial section and providing upwardly presented open cradle portions adjacent to the helices respectively, adjacent bight portions lying in respective vertical planes which are disposed at an angle of approximately 60 with respect to each other, said horizontal medial sections of the two lengths of wire stock, in combination with the adjacent sides of the bight portions, constituting a saddle for reception over said pair of reinforcing rods whereby the anchoring insert is supported solely by such rods, adjacent cradle portions being adapted loosely to receive therein in horizontal supporting relationship an elongated anchor bar, the sides of said bight portions remote from the medial sections being welded to the outside surfaces of the helices respectively, the upper ends of said remote sides of the bight portions projecting upwardly above the level of the medial sections and above the open upper ends of the cradle portions, said anchoring insert further including a pair of wing parts, one for each helix, each wing part being in the form of a length of wire stock bent into substantially triangular loop form so as to provide a horizontal base with upwardly converging sides, the upper ends of said latter sides being provided with vertical extensions which are welded to the outer side of the adjacent helices.

References Qited by the Exaer UNITED STATES PATENTS 1,139,987 5/15 Lukens 50-517 1,817,059 8/31 Bitney 50-517 2,345,976 8/44 Hillberg 50-517 2,794,336 6/57 Ballou 50-474 FRANK L. ABBOTT, Primary Examiner.

JACOB L. NACKENOFF, BENJAMIN BENDETT,

Examiners.

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