LIFTING ANCHOR FOR PRECAST CONCRETE STRUCTURES
A lifting anchor for a precast concrete structure is made from a single strand of metal bar stock. The anchor includes undulations or waves that ensure proper engagement of the anchor in a desired compressed concrete zone and also minimizes interference with the pre-stressed strands in the concrete structure. The anchor can be positioned in different orientations in the structures, depending on functional requirements of particular structures, and can be made from a single strand of bar stock of desired cross-sectional thickness and shape (e.g., round or square). Also, the undulations or waves in the legs of the anchor can extend in one or both directions from a plane defined by the anchor's legs.
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The present application claims the filing benefit of U.S. Provisional Application Ser. No. 62/301,150, filed Feb. 29, 2016, which is hereby incorporated herein by reference in its entirety.
FIELD OF THE INVENTIONThe present invention generally relates to lifting anchors for precast concrete structures, and more particularly to lifting anchors and assemblies for reinforced and/or prestressed concrete beams, girders, slabs, columns, panels, and the like.
BACKGROUND OF THE INVENTIONPrecast concrete structures are often used in building constructions, and lifting anchors are commonly embedded or cast in the precast concrete structures to facilitate handling, since these structures can be difficult to hoist and position due to their weight, bulkiness, and susceptibility to damage, such as cracking, chipping, and other breakage. With respect to prestressed concrete structures, precompressed tensile zones of the structure can make the structure more susceptible to damage during handling and installation, such as when lifting anchors are ineffectively designed and/or located to cause interference with the prestressed strands embedded in the structure.
SUMMARY OF THE PRESENT INVENTIONThe present invention provides a lifting anchor that is configured to be embedded in a precast concrete structure, such as a single-tee beam or double-tee slab or the like, that has pretensioned or prestressed strands forming a compressed zone or zones in the concrete structure. The lifting anchor includes a single strand or piece of metal bar stock that is bent to have a pair of elongated, parallel legs and a central section that integrally interconnects the legs and is used as the attachment point for connecting lifting chains or cables or the like. A lower end section of each of the legs includes undulations, such as waves, that are configured to engage the compressed zone in the concrete structure in a manner that provides a stable and secure lifting point and minimizes interference with the prestressed strands. The lifting anchor may be positioned to straddle opposing sides of the prestressed strands or to be disposed between spaced apart prestressed strands, thus allowing the lifting anchor to accommodate differently shaped and configured precast concrete structures in a manner that prevents interference with the prestressed strands.
According to one aspect of the present invention, a lifting anchor is configured to be embedded in a precast concrete structure. The lifting anchor includes a single strand of metal bar stock that is bent to have a pair of elongated legs and a central section that integrally interconnects the pair of elongated legs. A lower end section of each of the pair of elongated legs includes undulations that are configured to engage in a compressed zone of a concrete structure resulting from prestressed strands cast in the concrete structure and configured to minimize interference with the prestressed strands.
According to another aspect of the present invention, an apparatus includes a precast concrete structure that has a surface-forming panel portion, a panel-reinforcing rib portion, and prestressed strands disposed within the rib portion. A plurality of lifting anchors are positioned within the rib portion, where the plurality of lifting anchors each include a single strand of metal bar stock that has a pair of parallel legs and a leg-connecting section. A lower end section of each of the pair of parallel legs includes undulations shaped to engage in a compressed zone in the rib portion proximate the prestressed strands.
According to yet another aspect of the present invention, a method is provided for forming a concrete structure. The method includes providing a plurality of lifting anchors that each have a single strand of metal bar stock that includes a pair of parallel legs and a leg-connecting section, where a lower end section of the legs includes undulations bent into the single strand. Concrete is cast to form a precast concrete structure that includes a surface-forming panel portion, a panel-reinforcing rib portion, and prestressed strands that extend along a length of the rib portion. Prior to hardening of the precast concrete structure, the plurality of lifting anchors are disposed within the rib portion with the undulations positioned to engage a compressed concrete zone in the precast concrete structure and to minimize interference with prestressed strands in the concrete structure.
These and other objects, advantages, purposes, and features of the present invention will become apparent upon review of the following specification in conjunction with the drawings.
Referring now to the drawings and the illustrative embodiments depicted therein, a lifting anchor 10 (
As shown in
As also illustrated in
With further reference to
The lifting anchor 10 can be positioned to extend between spaced apart prestressed strands 42, such as shown in
With reference to the lifting anchor 10 shown in
The wave shape of the undulations 16 shown in
In an additional embodiment, as shown in
With reference to
As shown in
As shown in
As further shown in
For purposes of this disclosure, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in
Changes and modifications in the specifically described embodiments may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law. The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described.
Claims
1. A lifting anchor configured to be embedded in a precast concrete structure, said lifting anchor comprising:
- a single strand of metal bar stock bent to include a pair of elongated legs and a central section that integrally interconnects the pair of elongated legs; and
- wherein a lower end section of each of the pair of elongated legs includes undulations that are configured to engage in a compressed zone of a concrete structure resulting from prestressed strands cast in the concrete structure and configured to minimize interference with the prestressed strands.
2. The lifting anchor of claim 1, wherein the pair of elongated legs extend from the central section in substantially parallel alignment with each other.
3. The lifting anchor of claim 1, wherein the central section comprises an inverted V shape configured to engage a lifting chain.
4. The lifting anchor of claim 1, wherein the central section separates the pair of elongated legs away from each other at a spaced distance configured to dispose the pair of elongated legs on opposing sides of a vertical arrangement of the prestressed strands in the concrete structure
5. The lifting anchor of claim 1, wherein the central section and upper sections of the pair of elongated legs define a common plane, and wherein the undulations in the lower end sections of the pair of elongated legs extend from at least one side of the common plane.
6. The lifting anchor of claim 5, wherein the undulations are defined by the lower end sections of the pair of elongated legs bent to a wave shape with at least two wavelengths that extends from a side of the common plane.
7. The lifting anchor of claim 1, wherein the pair of elongated legs are configured to be disposed between the two vertical arrangements of the prestressed strands.
8. The lifting anchor of claim 1, wherein the single strand comprises one of a generally square cross-sectional bar stock and a generally round cross-sectional bar stock.
9. An apparatus comprising:
- a precast concrete structure including a surface-forming panel portion, a panel-reinforcing rib portion, and prestressed strands disposed within the rib portion;
- a plurality of lifting anchors positioned within the rib portion;
- wherein the plurality of lifting anchors each comprise a single strand of metal bar stock that includes a pair of parallel legs and a leg-connecting section; and
- wherein a lower end section of each of the pair of parallel legs includes undulations shaped to engage in a compressed zone in the rib portion proximate the prestressed strands.
10. The apparatus of claim 9, wherein the prestressed strands are disposed at spaced locations along a length of the rib portion, and wherein the leg-connecting section and upper sections of the pair of parallel legs extend generally in a common plane.
11. The apparatus of claim 10, wherein the common plane extends parallel to the prestressed strands.
12. The apparatus of claim 10, wherein the common plane extends perpendicular to the prestressed strands.
13. The apparatus of claim 10, wherein the undulations extend from at least one side of the common plane, and wherein the undulations are configured to minimize interference with the prestressed strands.
14. The apparatus of claim 9, wherein the leg-connecting section separates the pair of parallel legs away from each other at a spaced distance configured to dispose the pair of parallel legs on opposing sides of the prestressed strands.
15. The apparatus of claim 9, wherein the undulations are defined by the lower end sections of the pair of parallel legs each bent to a wave shape with at least one wavelength.
16. The apparatus of claim 15, wherein the pair of parallel legs are disposed between the two prestressed strands.
17. The apparatus of claim 9, wherein the single strand comprises one of a generally square cross-sectional bar stock and a generally round cross-sectional bar stock.
18. A method of forming a concrete structure, said method comprising:
- providing a plurality of lifting anchors that each comprise a single strand of metal bar stock that includes a pair of parallel legs and a leg-connecting section, wherein a lower end section of the legs includes undulations bent into the single strand;
- casting concrete to form a precast concrete structure that includes a surface-forming panel portion, a panel-reinforcing rib portion, and prestressed strands that extend along a length of the rib portion; and
- wherein, prior to hardening of the precast concrete structure, the plurality of lifting anchors are disposed within the rib portion with the undulations positioned to engage a compressed concrete zone in the precast concrete structure and to minimize interference with prestressed strands in the concrete structure.
19. The method of claim 18, wherein the leg-connecting section and upper sections of the pair of parallel legs extend generally in a common plane.
20. The method of claim 19, wherein each of the plurality of lifting anchors is positioned for its common plane to extend generally parallel or perpendicular to the prestressed strands.
Type: Application
Filed: Feb 28, 2017
Publication Date: Aug 31, 2017
Applicant:
Inventor: Marinus Hansort (St. Pete Beach, FL)
Application Number: 15/444,387