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.
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.