US2772560A - Pick-up device for pre-cast concrete slabs - Google Patents

Description

Dec. 4, 1956 Filed June 28, 1952- H. P. NEPTUNE 2,772,560

PICK-UP DEVICE FOR FREE-CAST CONCRETE SLABS 2 Sheets-Sheet J INVENTOR. HERMAN P NEPTUN Agem.

Dec. 4, 1956 H. P. NEPTUNE PICK-UP EVICE FOR PRE-CAST CONCRETE SLABS FiledJune28, 1952 2 Sheets-Sheet 2 INVENTOR. HERMAN P NEPTU/VE.

United States Patent Office 2,772,560 Patented Dec. 4, 1956 2,772,560 PICK-UP DEVICE FOR PRE-CAST CONCRETE SLABS Herman P. Neptune, Los Angeles, Calif. Application June 28, 1952, Serial No. 296,208

3 Claims. (Cl. 72-195) 7 This invention relates generally to concrete structures and more particularly to building structures of the socalled pre-cast, tilt-up concrete wall panel types. Specifically, the invention is concerned with embedment devices by which pick-up or lifting units can be secured to pre-cast concrete slabs or panels to facilitate tilting the latter from a horizontal position in which the panels are cast, to an erect position to form the walls or other parts of a building.

Concrete building structures are currently erected by what is termed the tilt-up panel method. Such a building method consists in pre-casting the structural components, such as large, rectangular wall panels, upon a smooth, coated, horizontal surface, for example a concrete floor, such wall panels being usually reinforced by a network of steel rods embedded in the concrete. After the pre-cast wall panels have cured for a predetermined period of time, they are lifted from the floor by a boom-type crane which sets them in erect position on footings to form the wall, various means being employed for joining the panels together or to columns of the building structure. Such pre-cast wall panels are frequently of large area and their weight may be of the order of approximately twenty tons. Since the panels are lifted by first tilting them upwardly on an edge, it follows that any pick-up unit secured to a panel and to which a crane lifting beam is connected must necessarily be of strong construction and securely fastened to the panel. A pick-up unit most commonly employed for this purpose consists of a lifting angle-plate which is bolted against the upper surface of the pre-cast panel by means of studs projecting from the slab, nuts being screwed onto the outer extremities of the studs and against the plate. The inner ends of the studs are usually screwed into nuts which are welded between the steel reinforcing rods or to separate rods to be embedded in the panel. While such pick-up units are used extensively in the construction field, they are subject toseveral disadvantages. For example, the welding of the anchoring nuts to the rods is time-consuming and special care must be exercized in spacing them properly in accordance with the spacing of the stud holes in the lifting plate. fact that welded joints are not thoroughly reliable since they may rupture to release the anchoring nuts which then may pull out from the panel to allow the latter to drop onto. the casting surface and crack or break. In an effort to avoid such a serious condition, various expedients have been proposed but in all such cases of which I am aware, the various insert or embedment elements, whether nuts, plates, sleeves or other forms, comprise either anassembly of welded elements orindividual parts which are Welded directly to the rods of the panel. Consequently, before the advent of my invention no fully satisfactory pick-up unit has been devised for the purpose and the conventional devices referred to above have beentolerated.

It'is therefore an important object of this invention to provide an insert or embedment means for attaching lifting plates, angles, eyebolts or other lifting means to pre-cast concrete panels, such embedment being a unitary structure capable of being effectively joined to the reinforcing of a panel without welding.

Another serious disadvantage resides in the Another object of the invention is to provide an anchoring means which comprises a threaded element, such as a nut, plate, sleeve, etc., and means for retaining the element against the under surfaces of a pair of the reinforcing or other rods of the concrete panel being precast. In accordance with the invention, the element held in place against the parallel rods includes a nut, which is of sufiicient width to extend transversely across said pair of rods, and clamping means engageable between the rods and nut to retain the latter firmly seated against the under surfaces of the rods.

Another object is to provide an embedment, of the character referred to, in which the clamping means comprises a pair of resilient clip elements each of which has a central portion engaging the nut and hook-like end portions adapted to engage around one of the rods. According to the invention, the clip elements are caused to flex or bow as their end portions are hooked around the rods, the tensioned elements then acting to seat the embedment nut firmly in place against the rods and thus retain the nut in position to be embedded in the concrete when the same is poured and tamped into the forms and around the rods. Thus, by this means the embedment nuts are effectively held in place and may be quickly and conveniently installed within the form without welding and without tools of any kind. Moreover, since each embedment nut is yieldingly held in place by the resilient clip elements before the concrete is poured, inadvertent striking of a nut by a workman will not dislodge the nut but rather will merely tiltit, the clip elements yielding to allow such action and then functioning to restore the nut to its original clamped position. In addition, by this mounting means the nuts may be readily shifted on the reinforcing rods to accurately space them in accordance with the spacing of the bolt holes of the angle plate which is to be applied against the upper surface of the cast concrete .panel for lifting purposes.

ally outwardly of the slots being swayed or forced inwardly to overlie said central portions to retain the latter in the slots.

Itis a further object of my invention to provide an embedment which has a relatively large surface for engagement with the reinforcing rods, this object being most practically attained through the use of a washer which may be interposed between the nut and the pair of reinforcing rods.

A further object is to provide means carried by the nut for coring a hole in the concrete slab by which astud, bolt or like fastening element may be screwed downwardly into the nut. This objective is accomplished by means of a screw which is threaded downwardly through.

thenut we point therebelow, the screw being greased or otherwise coated to prevent bonding of the concrete thereto during the casting of the panel and to allow withdrawal of the screw-type core from the panel after the A still further object of the invention is to provide an embedment device which is of simple, yet very strong construction and capable of being manufactured at a relatively low cost, one which may be quickly installed to thus minimize the over-all cost of producing the precast concrete panels, and one which does not rely upon weld connections and thus affords greater safety and insurance against dropping of the panel as the latter is tilted on and raised from the casting surface.

Another object is to provide an embedment means in which the nuts may be anchored b neath and extend between one of the reinforcing rods of the panel and a separate rod or rods placed in the form and extending parallel to said reinforcing rod. A related object is to provide such a device whichmay be employed in connection with precast, unreinforced concrete panels by simply pro-connecting the embedment nuts to steel rods and embedding the assemblies in the concrete.

Another object is to provide an anchoring device in which the anchoring nut may be joined to the reinforcing rods of a concrete panel at crossing points of the rods, in which case a relatively short rod is wired in place to extend diagonally of the crossing rods at a short distance from the intersection to provide a triangular base against which the nut is clamped by three resilient, wire clip elements each engaging a separate rod. In this embodiment of the invention, the anchoring nut is provided with three slots or grooves in its under surface, said grooves receiving the central portions of the clip elements and locating the latter directly beneath the respective rods to which their hooked ends are engaged. Since the rods are necessarily at different levels, the anchoring nuts have grooves of arcuate form and of varying depths in their upper surfaces for receiving the rods, the three clip elements having their hooked end portions or legs of appropriate lengths to extend around the respective rods.

Further objects will appear from the following description and from the drawings, which are intended for the purpose of illustration only, and in which:

Fig. l is a perspective view of a pre-cast concrete wall panel or slab to which are attached lifting plates or angles by which the panel may be tilted and raised by a crane;

Fig. 2 is a perspective view of one form of my anchoring or embedment device for use in securing a lifting means, such as the lifting angle of Fig. l, in place against a panel;

Fig. 3 is a cross-sectional view, taken on line 33 of Fig. 1;

Fig. 4 is a cross-sectional view, taken on line 4-4 of Fig. 3;

Fig. 5 is a small scale cross-sectional view similar to Fig. 3, showing a lifting eye-bolt secured in place;

Fig. 6 is a perspective view of an alternative form of the anchoring device, showing it applied to use at the crossing point of two of the reinforcing rods of a concrete panel; I

Fig. 7 is a plan View of the device illustrated in Fig. 6;

Figs. 8, 9 and are cross-sectional views, taken'respectively on lines 88, 99 and 10-40 of Fig. 7;

Fig. 11 is a perspective view of the modified form of anchoring nut employed in the device of Figs. 6 to 9; and

Fig. 12 is a vertical sectional view through an anchoring device of further modified form.

Referring first to Figs. 1 through 5 of the drawings, the present improved embedment or anchoring device is shown as applied to use, for example, in connection with a pro-cast concretewall panel or slab 16. In accordance with the usual procedure, the panel 16 is cast in a suitable rectangular form (not shown) which is set up upon a smooth surface, such as a concrete floor. When the wall panel 16 is to be of the reinforced type, areticulated network of reinforcing rods 17 is suitably supported within the form to be embedded in the panel when the concrete is poured into the form. Upon removal of the form and curing of the concrete for a predetermined period of time, the panel is tilted upwardly on the casting surface, then lifted by a boom type crane and set up in vertical position upon suitable footings to form part of a building wall. As previously pointed out, the panel is lifted at its end which is to form the upper edge portion of the wall and pick-up means are provided at this end by which the lifting hooks or harness of the boom cable can be connected to the panel. Many forms of anchoring means, previously referred to, have been employed for detachably connecting various types of pick-up devices to the panels. For example, it is common practice to attach pick-up angles, such as those shown at 18 in Fig. 1, against the upper surface of the panel by means of studs 19 which are inserted downwardly through holes in the angles 18 and in the concrete, the lower ends of the studs being screwed into large anchor nuts pre-welded to and between parallel reinforcing rods 17 of the network. Nuts 21 screwed onto the upper projecting ends of the studs 19 secure the lifting angles 18 in place. The angles 18 have holes through which the hooks 22 of the lifting cables 23 engage during tilting and lifting of the panel. Due to the relatively small effective area of the anchoring nuts embedded in the concrete slab and the fact that they are merely welded at their sides to the reinforcing or separate rods, an insecure attachment of the pick-up devices frequently occurs with the result that the anchoring nuts may break away from the rods to which they are welded, thus allowing them to pull through the overlying cast concrete. Such a deleterious condition may result in dropping of the panel to cause cracking or breaking of the same and in serious injury to the workmen.

It is the aim of my invention to provide an improved means for securing the pick-up devices in place against a panel so as to obviate the serious condition referred to above. Referring to Figs. 2 to 4, the improved anchoring or embedrnent device includes a large nut 24 which is adapted to be placed in position to underlie a pair of the reinforcing rods 1'7. Preferably, one of the rods, designated by the numeral 17, may be an extra rod installed alongside a rod 17 and parallel thereto, the nut 24 underlying these rods as shown. The rod 17' may be of suflicient length to serve as a transverse support for several of the anchoring nuts, as illustrated in Fig. l, or in other instances, relatively short rods, extending longitudinally of the panel 10 may be employed.

The anchoring or embedment nut 24 is provided with a pair of slots or grooves 26 in its under surface, these grooves being formed at opposite corners of the nut. Extending through the slots 26 are the central or intermediate portions 27 of clip elements 28, these portions being retained in the slots by means of ears 29 which form the outer corner portions of the nut, the ears being peened or swaged inwardly (Fig. 3) to reduce the width of the slots for this purpose. The fee ends of the clip elements 23 are provided with hooks 31 which are adapted to engage over the rods 17 and 17', so as to hold the nut 24 in place against the under sides of the rods.

In order to provide adequate bearing surface area for the nut 24, a large washer 32 is preferably interposed between the nut and the rods, as shown.

When applied to use within the concrete form, each anchoring or embedment device is provided with means for coring a hole in the concrete panel. This core means consists of a relatively long stud 33 which is screw threaded throughout its length to adapt it to pass through the washer 32 and to be screwed into the nut 24 from above, with its lower end projecting below the nut (Fig. 2), the stud havinga screw-driver slot 3d in its upper end.

The anchoring device of this invention is a self-' contained unit ,comprisingthe nut 24, washer 32, clip elements 28 and stud 33, these parts being furnished to the contractor in assembled condition, ready for use in concrete forms. To install, adevice of this char acter in a concrete form, preparatory to pouring the concrete panel 10, the device is placed in the position shown in Fig. 2, that is, with the upper portion of its stud 33 extending upwardly through the space between the rods 17 and 17' and with the Washer resting against the under sides of these rods.

The free ends of the clip members 28 then are individually forced upwardly, as indicated by the broken lines in Fig. 2, and their hooks 31 are engaged over the rods as shown by the full lines. With the four hooks 31 thus engaged, the clip elements 28 assume an upwardly flexed or bowed contour to become tensioned, the inherent resiliency of the elements maintaining their hooks positively connected to the rods. Due to such resiliency, in the event that the stud 33 is inadvertently struck a lateral blow or stepped upon by a workman, the clip elements 28 may flex downwardly and thereafter assume their bowed condition to restore the nut and washer to original position. By this provision, inadvertent dislodging of the device is effectively prevented.

The required number of the anchoring devices are in stalled within the form in the manner explained above and when a pair of the devices are to be employed for anchoring each pick-up angle 18 in place, these devices are adjusted along the rods 17 and 17' to space their studs 33 at a distance which is equal to the spacing of the stud holes of the angle 18. The studs 33 are then screwed into or from the nuts 24 to locate their upper slotted ends in the plane of the upper edges of the form, that 'is, the plane of the upper surface of the panel to be produced. The studs 33 then are coated with heavy grease or other bond-inhibiting substance and the anchoring devices are ready for use.

The panel 16 may now be cast in the rectangular form by simply pouring the plastic concrete thereinto and tamping it into place around the rods 17, 17 and around the anchoring devices to embed these parts. With the reinforced panel 16 thus cast, it is allowed to set and cure for a predetermined period of time, when the studs 33 are removed by unscrewing them upwardly from the nuts 24- by means of a heavy duty screw-driver engaging in the slots 34.

Removal of the studs 33 leaves cored holes 36 in the upper portion of the concrete panel 16 for receiving the studs 19 which may now be screwed downwardly into the embedded anchor nuts 24 as shown in Figs. 3jand 4. With the studs 19 thus applied, their upper ends project above the panel 16 and through the stud holes of the pick-up angles 18 which are placed against the panel. The nuts 21 are finally screwed onto the upper ends of the studs 39 to clamp the lifting angles against the panel 16 as shown in Fig. 1.

It is to be particularly noted that the embedded anchoring device, including the rods 17 and 17', nut 24,.washer 32 and clip elements 28, provides a very strong, stable and otherwise efficient means for securing the attaching studs i9 in place and eifect-ively resists any tendency of the nuts 24 to pull from the concrete panel to damage the latter and to allow it to fall as it is being tilted and bodily lifted into place in the wall line of the building structure. After the panel 16 has been secured in its required position, the cables 23 are disconnected from the lifting angles 18 and the latter are removed from the panel 16 by simply removing the nuts 21. The studs 19 then are unscrewed from the nuts 24 and the then open cored holes 36 are filled with grout.

In the case of a pro-cast concrete panel of gin-rein; forced type, the anchoring device may be applied to use by simply installing a. pair, or pairs, of therods '17 in the form in any suitable mannerto provide supports for the devices which then may be er'nbedded by the procedure outlined above.

In the event that the pick-up means consists merely in eye-bolts, such as indicated at 38 in Fig. 5, such bolts are simply screwed into the nuts 24 as shown and are later removed, after the panel has been set up.

Referring now to Figs. 6 through 10 of the drawings, my invention further contemplates the provision of an anchoring device which is designed primarily for use at the crossing points or intersections of the reinforcing rods of a tilt-up concrete panel. This alternative device includes an anchor nut 40 which, as shown best in Fig. 10, is in the form of a cylindrical block having a threaded bore 41. The nut 40 may have an enlarged lower end providing a peripheral flange 42. At its upper end, the nut 40 has three upwardly facing, angularly related grooves 43, 44 and 45, these grooves being in the form of an isosceles triangle as viewed in plan. It is also to be noted that the grooves are cut at different depths with respect to the upper end of the nut 40. To be more specific, the groove 43 is relatively shallow while the groove 44 is somewhat deeper. The third groove 45 is still deeper and, as shown best in Figs. 6 and 8, is inclined slightly. The anchor nut 40 is adapted to receive a core-stud 47 which is screwed thereinto as shown.

The anchoring device illustrated in Figs. 6 to 10 is applied to use in connection with reinforcing rods 50 and 51 which cross or intersect each other at right-angles. These rods, which are typical of the many crossing rods of the reticulated reinforcement structure of the concrete panel, are tied together at the intersection 52 by means of a wire 53 (Fig. 7). A third, relatively short, rod 55 is wired at 56 and 57 against the under surfaces of the rods 50 and 51 and extends across the right included angle therebetween at a suitable distance from the intersection 52. Since the rods 50 and 51 are disposed in different horizontal planes, it is seen that the auxiliary rod 55 must be inclined in order to contact these rods.

The nut 40 is adapted to be disposed within the open triangular area bounded by the rods 50, 51 and 55, the grooves 43, 44 and 45 being so angularly related and of appropriate depth to adapt them to receive the respective rods 50, 51 and 55. With the rods thus seated in the grooves, the nut 4b is so disposed that it bears equally against the three rods with the vertical core-stud 47' located at substantially the center of the open triangular area between the rods.

Means are provided for retaining the nut 40 in position against the rods 50, 51 and 55. This means comprises clip members 60, 61 and 62 of substantially the same construction as the clip elements 28 previously described, each element having a central portion and hooks 65 at its ends. The clip elements 60, 61 and 62 are carried by the nut 40 at the lower end thereof, being held in slots 66, 67 and 68 formed in the bottom of the flange 42. The slots 66, 67 and 68 are located beneath the respective grooves 43, 44 and 45 and parallel thereto so as to dispose the clip elements 60, 61 and 62 in line with the respective rods 50, 51 and 55 to adapt their hooks 65 to engage thereover as shown in the several views, the clip elements crossing one another at different levels as indicated best in Figs. 6 and 7.

- The modified anchor device is applied to use in a manner similar to that previously outlined in connection with the device of Figs. 1 through 5, the nut 40 being placed upwardly against the rods 50, 51 and 55, with the latter seated in the grooves 43, 44 and 45, after which the clip elements 6t), 61 and 62 are flexed upwardly to engage their hooks .65 over the respective rods. By this provision, the nut 40 is held firmly against the rods and is keyed against rotation with respect thereto. After the device has been embedded in the poured-concrete 70, the stud 57 is. removed and replacedby a suitable liftingstud or eye-bolt, as desired: I d i p Referring now to Fig. 12, his within the concept of this invention to provide an anchoring device of the gen- -e ral' typ'e disclosed in Figs. 6 through 1T but in which the anchor nut 75 is made longer than the nut 40. In other respectsjthe nut ,75 is similar, being adapted who held in place against the under sides of the rods, for example the rods 51. and 55, by means of the respective clip elements 61 and 62. As shown, the nut '75 has an elongate upper portion 76, the extremity of which is disposed slightly'below the plane of the upper edge of the form in which the concrete is to be poured.

in applying the alternative nut 75 to use, a first cork plug 77 is inserted and wedged in the lower end of the threaded bore 78 of the nut. A second cork plug '79 is similarly forced into the upper end of the bore 78, this plug being of sutlicient length to project above the upper end of the nut to the upper surface of the concrete panel to be cast. The plugs 7'7 and 79 thus efiectively' seal the threaded bore 7 8 to prevent flow of the concrete thereinto. After the concrete has been poured into the form and has set sufliciently, the upper cork insert 79 may be removed to provide an upper cored hole 8 in the concrete which aligns axially with the bore 78. Any suitable threaded stud, eye bolt or other attaching or pick-up means, such as those previously referred to, then may be screwed down into the nut 75, which is firmly embedded in the concrete. It will be apparent that the nut 75 may be made with its lower end closed, in which case the lower cork plug 77 may be dispensed with.

It will be observed from the foregoing that the present invention provides a simple, inexpensive and highly practical anchoring device for use particularly with pick-up devices used in connection with pre-cast concrete tilt-up construction panels. As an important feature, the embedrnent or anchoring means is retained within the concrete form, to be embedded therein, by simple, flexible, clip elements or retainers which engage the reinforcing rods of the concrete panel to retain the anchoring nut in place without the necessity for welding the nut to the rods. By this means, therefore, the anchoring means is positively held in its embedded position and the possibility of the nut working loose or pulling out from the concrete panel, as the latter is lifted, is wholly avoided. Consequently, the present anchoring device constitutes an important improvement over the welded types previously employed for the same purpose, which occasionally become separated from the reinforcing rods to cause dropping of the panels. As another feature, the improved anchoring device is adapted for usein connection with precast panels of eitherthe reinforced or tin-reinforced types; in the latter case, the device is applied to use by simply connecting the anchoring nut to relatively short pieces of rod to provide an assembly which then may be placed in the concrete form and embedded in the concrete poured therearound. In this respect, itis also pointed out that the anchoring devices may also be utilized for analogous purposes; such as embedding anchoring nuts in the floor or a concrete foundation upon which a machine is to set up, the embedded nuts being spaced to receive bolts employed to fasten the machine base to the floor or foundation. Another advantage of the invention resides in the fact that the anchoring device may be used in connection with either two parallel rods, or two crossing rods when it is desired to locate the lifting means at intersections of the reinforcing rods. In either case, the clip members or clamping wires are pre-assembled on the anchoring nut so that such assembling of the components at the construction site is unnecessary. Thus, the procedure of pre-casting the concrete panels is greatly expedited to minimize the over-all cost of the concrete structure. In addition, when the embedment or anchoring device is connected to the reinforcing rods of a panel the use of saddles or chairs for holding the device in proper vertical position within the form is unnecessary. In view of these various features, it is apparent that the present invention provides an important advancement in the art to which it pertains. 7

Considerin h present invention in its broadest aspect, the anchoring means consists generally in an anchor nut which is retained in place against the under side of any suitable embedment means to be embedded in the con} crete. 'Eor example, it is within the present concept to position the nut against the under side of the usual reinforcing rods of a concrete panel, against the under side of one or more of the reinforcing rods and one or more auxiliary rods installed for this specific purpose, or against the under side of separate rods. In the later case, the entire assembly of the rods, nut, stud and retainer elements is supported in proper position by means of conventional saddles or chairs. It is also within the purview of this invention to embed the anchor nut beneath one or more rods and a plate or entirely beneath a plate, mesh or other embedment member, having a relatively large bearing surface and capable of retaining the nut firmly embedded in the concrete.

In accordance with the provisions of the patent statutes, l have described the principle of application of the improved embedment or anchoring device, together with the constructions which I now consider to represent the best embodiments of the device, but I wish it to be understood that other modifications might be made without departing from the spirit of the invention. Consequently, I do not wish to limit myself in this respect, but desire to be afforded the full scope of the appended claims.

I claim as my invention:

1. In a concrete slab having a plurality of reinforcing rods therein, said rods having a space therebetween, an anchoring device comprising a not having spaced first and second faces, an axially threaded bore in the nut passing through said faces, the first face of said out bearing against a plurality of said rods with the threaded bore being accessible through the space therebetween, said second face having a plurality of elongated wire retaining elements secured thereto, said retaining elements having means at the ends thereof engaging said rods at points thereon spaced from said nut and clampingly securing said first face against said rods.

2. A reinforced slab as recited in claim 1 wherein said rods are disposed in spaced parallel relation, said nut having spaced grooves on said second face and said wire elements being disposed within said grooves and fastened therein, the means at the ends of the wire elements corn.- prising hooks, the individual hooks being disposed in planes substantially normal to the axes of the rods.

3. A reinforced slab as recited in claim 1 wherein at least three rods intersect in substantially co-planar angular relation, said space between the rods being located at'the intersection thereof, said first face of said nut having a plurality of substantiallysemicircular grooves thereon disposed in angular relation, each of said rods being disposed in a respective groove, said second face of said not having a plurality of angularly positioned seating grooves therein, a wire retaining element occupying each of said seating grooves, the means at the ends of the wire retaining elements comprising hooks, and each of said hooks being disposed in a plane substantially normal to the axis of the rod engaged thereby.

References Cited in the file of this patent UNITED STATES PATENTS 758,910 Grattelo et a1 May 3, 1904 375,396 White Dec. 31, 1907 1,004,226 Ahern Sept. 26, l9l1 1,463,863. Zents Aug. 7, 1923 1,945,707 Sharp Feb. 6, 1934 1,999,508 Mathews Apr. 30, 1935 2,127,050 Smith Aug. 16, 1938 2,266,832 Tinnerman Dec. 23, 1941 2,345,650 Attwood Apr. 4, 1944 2,531,576 McClellen et al Nov. 28, 1950 FORE GN. PATENTS 81,152 Austria Aug. 25, 1920

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