COIL DISK ANCHOR

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Application Ser. No. 63/627,891 filed on Feb. 1, 2024, the disclosure of which is incorporated by reference herein in its entirety.

FIELD

The present disclosure relates generally to a lifting anchor and/or connector which may be embedded in a precast concrete structure.

BACKGROUND

Lifting anchors are frequently used with precast concrete structures, such as precast concrete panels, to lift and maneuver the precast concrete structures into position at a worksite. The anchors are made of high-strength steel, often with hot forged ends. The upper end, or head, typically extends above the precast concrete structure in order to be engaged by a lifting eye associated with lifting equipment, such as a crane. The lower end, or foot, has a diameter greater than that of a shaft of the anchor and is embedded in the precast concrete structure to create lifting capacity.

Lifting eyes remain attached to the anchor while the precast concrete structure is moved. Once the precast concrete structure is positioned and oriented at a desired location, the lifting eye is detached from the anchor. At such time, the anchor often provides little or no value.

Improved anchors are desired in the art. In particular, anchors which provide strong positive engagement with lifting equipment and provide secondary functionality would be advantageous.

BRIEF DESCRIPTION

In accordance with the present disclosure various aspects and embodiments will be set forth in part in the following description.

In accordance with one embodiment, an anchor for lifting precast concrete is provided. The anchor includes a shaft defining a first end, a second end, and a longitudinal axis; and a circular plate coupled to the second end of the shaft, the circular plate oriented perpendicular to the longitudinal axis, wherein the shaft defines an opening extending from the first end of the shaft towards the second end of the shaft in a direction generally parallel with the longitudinal axis, the opening having a sidewall with a helical thread.

In accordance with another embodiment, a precast concrete structure is provided. The precast concrete structure includes a concrete body; an anchor comprising: a shaft defining a first end and a second end and a longitudinal axis; and a circular plate coupled to the second end of the shaft, the circular plate oriented perpendicular to the longitudinal axis, wherein the shaft defines an opening extending from the first end towards the second end in a direction generally parallel with the longitudinal axis, the opening having a sidewall with a helical thread, wherein the circular plate is embedded in the concrete body and the shaft extends from the concrete body such that the opening is exposed from the concrete body.

In accordance with another embodiment, a method of installing a precast concrete structure is provided. The method includes threading an insert into an opening of an anchor, the anchor partially embedded in a precast concrete structure, wherein the anchor comprises a circular plate and a shaft coupled to the circular plate, wherein the circular plate is embedded in the precast concrete structure, and wherein the shaft extends from the precast concrete structure; lifting the precast concrete structure by applying tensile force to the insert; positioning the precast concrete structure; and securing a supporting fixture to the precast concrete structure by capturing a portion of the supporting fixture by a head of the insert while the insert is threaded into the opening.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the technology and, together with the description, serve to explain the principles of the technology.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description that follows makes reference to the appended figures, in which:

FIG. 1A is a side view of a worksite including a precast concrete structure being moved by lifting equipment in accordance with embodiments of the present disclosure;

FIG. 1B is a perspective view of a worksite including a precast concrete structure in accordance with embodiments of the present disclosure;

FIG. 1C is a cross-sectional side view of a precast concrete structure in accordance with embodiments of the present disclosure;

FIG. 2 is a perspective view of an anchor for use in lifting the precast concrete structure in accordance with embodiments of the present disclosure;

FIG. 3 is a side view of the anchor in accordance with embodiments of the present disclosure;

FIG. 4 is a top view of the anchor in accordance with embodiments of the present disclosure;

FIG. 5 is a cross-sectional side view of the anchor as seen along Line A-A in FIG. 4 in accordance with embodiments of the present disclosure;

FIG. 6 is a top schematic view of the precast concrete structure in accordance with embodiments of the present disclosure;

FIG. 7 is a cross-sectional side view of the precast concrete structure as seen along Line B-B in FIG. 6 in accordance with embodiments of the present disclosure; and

FIG. 8 is a perspective view of an anchor including a coil protector in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the drawings. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, each example is provided by way of explanation, rather than limitation of, the technology. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope or spirit of the claimed technology. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the disclosure.

As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. As used herein, the terms “comprises,” “comprising.” “includes,” “including” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Terms of approximation, such as “about,” “generally,” “approximately,” or “substantially,” include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, “generally vertical” includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

In general, anchors described herein (which may be referred to as coil disk anchors) allow for lifting, moving, and supporting of precast concrete structures. Additionally, the anchors may be used to attach permanent or semipermanent fixtures to the precast concrete structure. In this regard, the anchor can be used during construction (e.g., while the precast concrete panel is being transported, moved, and erected) and as part of regular use of the precast concrete structure (e.g., after construction is completed).

The anchor is partially embedded in the precast concrete structure with one end of the anchor accessible (exposed) from the precast concrete structure. The accessible end of the anchor includes an opening configured to receive an insert, such as a threaded bolt. The opening can include threads that allow the insert to be threaded into the opening. The insert is engageable with, or can be part of, lifting equipment and/or a fixture. For example, the insert (e.g., the bolt) can include a head and a threaded shank extending from the head or an all thread insertable into the opening of the anchor. When tightened relative to the opening (i.e., when threaded to the anchor), the insert can capture a fixture or other engageable structure between the head and a sidewall of the precast concrete structure (or through another type of engagement), thereby securing the fixture or engageable structure to the precast concrete structure. Thus, the anchor can be used to move and/or brace the precast concrete structure during manufacturing, during transit between a manufacturing site and a worksite, and/or at the worksite. Moreover, the anchor can be used to attach permanent or semipermanent fixtures and components to the precast concrete structure. For instance, once the precast concrete structure is positioned in place, a permanent or semi-permanent fixture can be installed (e.g., coupled to the precast concrete structure) via the anchor. The permanent or semipermanent fixture can remain coupled to the precast concrete structure after construction and onsite assembly is completed. In this regard, the anchor can be used both during construction and after completion of construction.

The anchor includes a circular plate embedded in the precast concrete structure. The circular plate is embedded in the precast concrete structure a sufficient distance from the surface of the precast concrete structure to increase loading capacity of the anchor. The circular plate reduces pullout of the anchor and provides high loading capacity for moving, supporting, and/or connecting the precast concrete structure to other structural components. In some implementations, the circular plate can have a circularity that is approximately 1.0, such that the anchor is free of, or essentially free of, sharp corners which might incur high stress concentrations, leading to fracture of the precast concrete structure.

Referring now to the drawings, FIGS. 1A and 1B illustrate a worksite 100 including a surface 102 upon which a precast concrete structure 104 is moved over, erected on, and supported by a plurality of supporting fixtures 106 each extending between the ground surface 102 and the precast concrete structure 104. The precast concrete structure 104 depicted in FIGS. 1A and 1B is a planar wall segment. The precast concrete structure 104 is configured to be moved by lifting equipment, such as a crane 101 (FIG. 1A). The crane 101 can include a lifting harness that engages the precast concrete structure 104 such that the crane 101 can move the precast concrete structure 104 into an appropriate position at the worksite 100 (FIG. 1B). In many implementations, the precast concrete structure 104 is moved between several different orientations as it is positioned at the worksite 100. For instance, the precast concrete structure 104 is often moved by lifting equipment in a horizontal orientation (FIG. 1A) and erected to assume a vertical orientation (FIG. 1B).

Typically, planar wall segments (and optionally other shaped wall segments) are combined together to form a wall of a building or other type of structure. As the planar wall segments are coupled together and/or coupled to nearby supporting structures, such as metal beams (not illustrated), the wall becomes rigid and stands by itself, i.e., without the use of supporting fixtures 106. However, during construction of the wall (or other structure), it is often necessary to brace the wall segment using one or more supporting fixtures 106.

The supporting fixtures 106 can be anchored to the surface 102, e.g., through one or more bolts, cleats, ties, feet, or the like, and extend towards the precast concrete structure 104 at a relative angle. The supporting fixtures 106 can be anchored to the precast concrete structure 104 to support the precast concrete structure 104 in a desired (e.g., upright) orientation. The supporting fixtures 106 can remain anchored to the precast concrete structure 104 until such time as a neighboring precast concrete structure (not illustrated) or another supporting structure is erected and the two or more precast concrete structures are anchored together and/or anchored to the supporting structure to solidify the wall. The supporting fixtures 106 are then removed.

FIG. 1B includes an enlarged view of a portion of the precast concrete structure 104 and depicts an anchor 108 disposed within the precast concrete structure 104. The anchor 108 is partially embedded in a body of the precast concrete structure 104. An exposed portion of the anchor 108 extends from the body of the precast concrete structure 104 and defines an engagement interface through which the supporting fixture 106 can be coupled to the precast concrete structure 104.

In some instances, the anchor 108 can be used to attach a permanent or semipermanent fixture to the precast concrete structure. That is, the fixture can remain attached to the anchor 108 after construction is completed. For example, FIG. 1C illustrates a cross-sectional side view of the precast concrete structure 104 with the anchor 108 embedded therein and a permanent or semipermanent fixture 164 coupled therewith. In the depicted embodiment, the fixture 164 is an L-shaped bracket. The L-shaped bracket may be used to attach one or more structural components (e.g., appliances, beams, etc.) to the precast concrete structure 104. However, the fixture 164 can also include other types of fixtures.

In a particular embodiment, the anchor 108 can receive an all thread 166 which extends outward from the precast concrete structure 104. The fixture 164 can be retained at the all thread 166, e.g., by nuts 168 and 170 or another known attachment protocol. Unlike the supporting fixtures 106 depicted in FIG. 1B which are removed after the structure is completed (or at least stable), the fixture 164 can remain attached to the precast concrete structure 104 after completion of the construction process. For example, the fixture 164 can be used to anchor a permanent assembly, such as a wall section, a floor section, a beam, or the like which remains attached to the precast concrete structure 104 after construction is completed.

FIGS. 2 to 4 illustrate the anchor 108 in accordance with an example embodiment. FIG. 2 illustrates a perspective view of the anchor 108; FIG. 3 illustrates a side view of the anchor 108; and FIG. 4 illustrates a top view of the anchor 108. Referring to FIGS. 2 to 4, the anchor 108 includes a shaft 110 having a first end 112 and a second end 114. In an embodiment, the first end 112 can have a tapered outer edge. The shaft 110 defines a longitudinal axis 116 extending between the first and second ends 112 and 114. In an embodiment, the first and second ends 112 and 114 of the shaft are oriented normal to the longitudinal axis 116. The shaft 110 has an outer sidewall 118 with a cylindrical shape. The outer sidewall 118 can have a constant (fixed) diameter, as measured between the first and second ends 112 and 114. In an embodiment, the outer sidewall 118 is free, or essentially free, of ridges, recesses, dimples, flanges, fingers, and other projecting or recessed features. In an embodiment, the shaft 110 is formed from a single-piece (has unitary construction). In use, i.e., when the anchor 108 is embedded in the precast concrete structure 104, the shaft 110 is not surrounded by any secondary elements, such as flanges, shoulders, or the like.

A circular plate 120 is coupled to the second end 114 of the shaft 110. For example, the circular plate 120 can be coupled to the second end 114 of the shaft 110 by a weld bead 122. The weld bead 122 can extend around the entire circumference of the shaft 110. In some instances, the weld bead 122 can be tapered or otherwise define a fillet between the circular plate 120 and the shaft 110. In another embodiment, the circular plate 120 can be coupled to the second end 114 of the shaft 110 by another type of fastener, such as a threaded fastener (not illustrated). By way of non-limiting example, the threaded fastener can extend through a central opening in the circular plate 120 and engage with a mating feature (such as threads) disposed at or adjacent to the second end 114 of the shaft 110. In yet another embodiment, the circular plate 120 can be coupled to the shaft 110 through adhesive, mechanical deformation (e.g., crimping of one or both of the shaft 110 and/or circular plate 120 together), an interference fit between the shaft 110 and circular plate 120 (e.g., where the circular plate 120 has an opening in which the shaft 110 is retained by interference), or the like.

The circular plate 120 can define a first major surface 124 and a second major surface 126 spaced apart from the first major surface 124 by a thickness T of the circular plate 120. In an embodiment, the first and second major surfaces 124 and 126 are oriented parallel with respect to one another. The first major surface 124 can be oriented perpendicular to the longitudinal axis 116 of the shaft 110. The circular plate 120 can define a peripheral surface 128 extending between the first and second major surfaces 124 and 126. In an embodiment, the peripheral surface 128 can abut at least one of the first and second major surfaces 124 and 126 at a right angle. In another embodiment, the peripheral surface 128 can abut at least one of the first and second major surfaces 124 and 126 at a rounded, chamfered or otherwise contoured interface.

Referring to FIG. 4, the circular plate 120 can have a circular shape as viewed parallel with the longitudinal axis 116 (FIG. 3). More specifically, the circular plate 120 can have an area that is at least 90% of an area of a hypothetical circle 130 circumscribing the circular plate 120, such as an area that is at least 95% of the area of the hypothetical circle 130 circumscribing the circular plate 120, such as an area that is at least 99% of the area of the hypothetical circle 130 circumscribing the circular plate 120. In the embodiment depicted in FIG. 4, the circular plate 120 has an area that is 100% of the area of the hypothetical circle 130 circumscribing the circular plate 120.

In an embodiment, the circular plate 120 can have an outer boundary defined by a high circularity value. Circularity C is generally defined by 4πA/P², where A is a value associated area and P is a value associated with the perimeter. In an embodiment, the circular plate 120 can have a circularity C of at least 0.7, such as at least 0.8, such as at least 0.9, such as at least 0.95, such as at least 0.99. In an embodiment, the circular plate 120 can have a circularity C of 1.0. The high circularity value for the boundary of the circular plate 120 can reduce stress concentration buildup in the nearby concrete of the precast concrete structure 104 (FIG. 1B). As a result, the anchor 108 can exhibit increased pullout resistance under high operating loads.

Referring again to FIG. 1B, the circular plate 120 is embedded in the precast concrete structure 104 below a pullout surface 132 of the precast concrete structure 104. The pullout surface 132 corresponds to a surface of the precast concrete structure 104 through which the anchor 108 exits, subjecting material between the circular plate 120 and the pullout surface 132 to high loading forces, particularly when the precast concrete structure 104 is lifted by the anchor 108 using a crane 101 (FIG. 1A) or other type of lifting equipment.

As depicted in FIGS. 2 to 4, the anchor 108 can further include an opening 134 disposed at the first end 112 of the shaft 110. The opening 134 can have a diameter D_O, that is no greater than 80% of a diameter D_S of the outer sidewall 118 of the shaft 110, such as no greater than 70% of the diameter D_S, such as no greater than 60% of the diameter D_S, such as no greater than 50% of the diameter D_S. The opening 134 can be centered within the shaft 110 and extend from the first end 112 towards the second end 114 of the shaft 110.

Referring to FIG. 5, in an embodiment the shaft 110 defines a height H and the opening defines a depth D, as measured from the first end 112 of the shaft 110 to a bottom 136 of the opening 134, where D is in a range between 0.2 H and 1.0 H. In an embodiment, the depth D of the opening 134 is at least 0.3 H, such as at least 0.4 H, such as at least 0.5 H, such as at least 0.6 H, such as at least 0.7 H, such as at least 0.8 H, such as at least 0.9 H. In an embodiment, the depth D of the opening 134 is equal to the height H of the shaft 110. For instance, the opening 134 can extend entirely through the shaft 110. In such instances, the bottom 136 of the opening 134 can be formed by the first major surface 124 of the circular plate 120.

In some embodiments, the opening 134 defines a generally uniform shape and size along the entire depth D of the opening 134. For example, the opening 134 can define a uniform diameter along the entire depth D of the opening 134. The depth D can extend part way or entirely between the first end 112 and the circular plate 120. In other embodiment, the opening 134 can have a variable shape and/or size. For instance, the opening 134 can include a first segment 138 and a second segment 140, where the first and second segments 138 and 140 have one or more different attributes or characteristics as compared to one another. For example, the first segment 138 of the opening 134 can have a first diameter D_O1 and the second segment 140 of the opening 134 can have a second diameter D_O2, where the second diameter D_O2 is greater than the first diameter D_O1. The second segment 140 can be disposed between the first segment 138 and the circular plate 120.

The opening 134 includes a thread 142 extending along an inner surface 144 of the opening 134. The thread 142 extends from the first end 112 of the shaft 110 towards the second end 114 of the shaft 110. In an embodiment the thread 142 comprises a plurality of threads rotationally staggered from one another. The thread(s) 142 are sized and shaped to receive a threadable insert, such as a bolt 146 (see also FIG. 1B). By way of example, the thread(s) 142 may be compatible with Unified National Coarse (UNC) bolts, Unified National Fine (UNF) bolts, coil thread bolts, or other types of helically threaded fasteners. In an embodiment, the bolt 146 includes a head 148 and a threaded shank 150. The threaded shank 150 can interact with the thread(s) 142 of the opening 134 to tighten and loosen the bolt 146 relative to the opening 134 by twisting the bolt 146 relative to the shaft 110. In another embodiment, the bolt 146 can include an all thread (i.e., threaded shank 150 absent head 148). Yet other inserts are considered herein.

In the depicted embodiment, the thread(s) 142 extend along the inner surface 144 of the first segment 138 of the opening 134 but not along the inner surface 144 of the second segment 140 of the opening 134. In this regard, the second segment 140 may be essentially free of (such as devoid of) threads. Dividing the opening 134 into two segments (one excluding threads) reduces tooling and manufacturing required to form the anchor 108 while providing sufficient engagement surface for the bolt 146 or other type of threadable insert and allowing the height H of the shaft 110 to be sufficiently long to expose the first end 112 from the precast concrete structure 104 (FIG. 1B) while the circular plate 120 is a sufficiently depth below the pullout surface 132.

In an embodiment, the shaft 110 can be formed from a cylindrical rod by drilling or otherwise extracting material from the cylindrical rod to form the first and second segments 138 and 140 of the opening 134. For instance, the first segment 138 can be drilled using a first size bit and the second segment 140 can be drilled using a second size bit different than the first size. A tap (not illustrated) can then be rotatably passed through the resulting bore, e.g., from the first end 112 towards the second end 114, to form the thread(s) 142. The tap can pass through the second end 114 of the shaft 110 and be removed from the opening 134. Next, the shaft 110 can be coupled to the circular plate 120, e.g., by first aligning the shaft 110 and circular plate 120 relative to one another such that the shaft 110 is perpendicular with the circular plate 120 and positioned at a central location therealong. The shaft 110 can then be welded to the circular plate 120 by applying the weld bead 122. In some instances, the shaft 110 can also be machined or otherwise finished to create a desired characteristic. For instance, an edge of the first end 112 of the shaft 110 can be beveled with the outer sidewall 118, the weld bead 122 can be grinded or smoothed, or the like.

In another embodiment, the anchor 108 can be unitary, i.e., constructed from a single piece (e.g., through a casting or forging process). In some instances, the thread(s) 142 can be formed during casting or forging. In other instances, the thread(s) 142 can be cut after the casting or forging process.

In an embodiment, the anchor 108 can define an aspect ratio [H/D_CP] as measured by a ratio of the height H of the shaft 110 to the diameter D_CP of the circular plate 120, in a range of 0.5 and 2.0, such as in a range of 0.6 and 1.95, such as in a range of 0.65 and 1.9, such as in a range of 0.7 and 1.75. For example, in an embodiment, the height H of the shaft 110 is 2.125 inches (in) and the diameter D_CP of the circular plate 120 is 3.0 in. In another embodiment, the height H of the shaft 110 is 4.125 in and the diameter D_CP of the circular plate 120 is 3 in. Anchors 108 with aspect ratios [H/D_CP] between 0.5 and 2.0, and more particularly between 0.65 and 1.9, and circular plates 120 with concentricity values greater than 0.95 exhibit reduced pullout from precast concrete structures 104, i.e., can withstand higher loading forces, as compared to other anchors. Without wishing to be bound by any particular theory, it is believed that anchors 108 described herein having aspect ratios [H/D_CP] between 0.65 and 1.9 and circular plates 120 with concentricity values greater than 0.95 can provide safe working load support (including a safety factor of 4.0) greater than 3 tons, such as greater than 5 tons, such as greater than 8 tons per anchor 108. These values are in excess of traditional anchors and allow for greater spacing between anchors while accommodating the same loading forces and safety factors when lifting and supporting precast concrete structures 104. Of course, it should be understood that a plurality of anchors 108 can be used simultaneously, thereby increasing safe working load support for a precast concrete structure 104. However, fewer anchors 108 reduces cost and worksite complexity, while increasing integrity and strength of the precast concrete structure 104.

In an embodiment, the anchor 108 can define an aspect ratio [D_S/D_CP] as measured by a ratio of the diameter D_S of the shaft (FIG. 3) to the diameter D_CP of the circular plate 120, in a range of 0.3 and 0.7, such as in a range of 0.35 and 0.6, such as in a range of 0.4 and 0.55. Within this range, it is has been found that force transfer exhibited on the precast concrete structure from the anchor 108 is maximized without exceeding anchor limitations and with ample safety factor. For example, where the anchor 108 has an aspect ratio [D_S/D_CP] between 0.3 and 0.7 and the shaft 110 has a height H of approximately 7 inches, the loading capacity of the anchor 108 without pullout from a precast concrete structure using a typical concrete slurry may exceed 17,000 pounds (lbs) while maintaining a safety factor of 4.0. Table 1, shown below, exhibits other example anchors 108 and associated loading capacity and safety factors. The Concrete Safe Working Load column is measured without the use of metal mesh or a low-density member (as described below) with the anchor 108 embedded in the concrete at an in-use position (i.e., with the first end 112 of the shaft 110 disposed below the pullout surface 132 by a distance corresponding to the coil protector 162). The listed Concrete Safe Working Load is provided in view of a 4.0 safety factor. That is, the listed load is reduced approximately 75% from maximum working load (i.e., approximately 75% of a force associated with a pullout or failure condition).

The anchors 108 can be introduced to the precast concrete structure during formation of the precast concrete structure, i.e., when the concrete is not yet fully cured. Referring to FIGS. 6 and 7, the anchor 108 can be positioned at a desired location, aligned, and embedded within a slurry of concrete 152 which forms the precast concrete structure 104. While not required, in an embodiment, the anchor 108 rests on a low-density member 154, such as foam. The low-density member 154 can be embedded within the concrete 152, e.g., prior to introducing the anchor 108 therein. The anchor 108 can be pushed into the slurry of concrete until contacting the low-density member 154 or positioned on the low-density member 154 with the concrete slurry introduced after. Metal mesh 156 can also be disposed in the concrete 152. The metal mesh 156 can include, for example, rebar forming a woven and/or crossing pattern within the concrete 152. The metal mesh 156 increases strength of the precast concrete structure 104, particularly against tension forces. The metal mesh 156 may be spaced apart from the low-density member 154. The anchor 108 can disposed in the concrete 152 such that the circular plate 120 is disposed between the metal mesh 156 and the low-density member 154 while the shaft 110 of the anchor 108 extends through an opening 158 formed in the metal mesh 156. In some implementations, the entire circular plate 120 is disposed within a perimeter of the opening 158 when viewed in a direction parallel to the longitudinal axis 116 of the shaft 110. In this regard, the metal mesh 156 is not disposed directly above any portion of the anchor 108 (when viewed parallel to the longitudinal axis 116 of the shaft), i.e., the metal mesh 156 does not directly hold the anchor 108. Traditional anchors often rely on contact with rebar or close positioning of the anchor relative to rebar or other metal structures within the concrete 152 to hold the anchor and prevent pullout. However, it has been found that arranging anchors to be directly supported by the rebar requires significantly more set up time (while the slurry is still wet), and greater skill and precision by the worker. Additionally, close proximity (or direct contact) between the anchor and rebar often results in cracks forming in the concrete proximate to the rebar and anchor, e.g., where settling occurred during hardening of the concrete. These cracks significantly weaken the resulting precast concrete structure. Anchors 108 described herein mitigate the occurrence of cracking, thus increasing operational loading capacity of the anchors 108.

In an embodiment, the shaft 110 of the anchor 108 emerges from the concrete 152 to allow for installation of the insert, e.g., the bolt In an embodiment, only the first end 112 of the shaft 110 can be exposed from the concrete 152. The first end 112 of the shaft 110 can be disposed at, or below, the pullout surface 132. A coil protector 162 (FIG. 8) may be used to form a recess 160 at the pullout surface 132. In this regard, the first end 112 of the shaft 110 can be disposed below the pullout surface 132. The coil protector 162 can interface with the first end 112 of the shaft 110 to enclose the opening 134 and prevent ingress of concrete or other contaminants into the opening 134 which might foul the thread(s) 142. The coil protector 162 is coupled to the anchor 108 while the concrete sets. Once the concrete 152 is set a sufficient amount, the coil protector 162 can be removed from the shaft 110 to expose the opening 134 and the recess 160. An insert can then be threaded into the opening 134 for use of the anchor 108 to manipulate the position of the precast concrete structure 104 (FIGS. 1A and 1B).

A worker can manipulate the precast concrete structure 104 by first threading the insert (bolt) 146 into the opening 134. The insert 146 may be engaged by a lifting eye or other structure and force can be applied to the precast concrete structure 104 through the insert 146. In some instances, the force can be a tensile force, such as when a crane lifts the precast concrete structure 104 for placement. Once the precast concrete structure 104 is placed at a desired location, the supporting fixture 106 can be coupled to the insert 146. As depicted in FIG. 1B, a portion of the supporting fixture 106 can be captured by the head 148 of the insert 146. The portion captured by the head 148 can be tightened towards the precast concrete structure 104 by threading the insert 146 into the opening 134 in the anchor and tightening the insert 146 to a desired or prescribed torque. After the precast concrete structure 104 is sufficiently supported, the anchor 108 can be used to support a permanent or semipermanent fixture 164 such as depicted in FIG. 1C.

Anchors, systems, and methods described herein allow for heavy precast concrete structures to be lifted without the use of a large number of anchors and with high safety factors. Circular plates are traditionally not used in anchors for precast concrete structures, particularly when the anchor has a circular shaft, as circular shaped anchors reduce overlap between the anchor and metal mesh (such as rebar), which is typically relied on for providing relatively high loading capacity. Moreover, anchors with circular plates and circular shafts have traditionally been seen as more difficult to position in concrete slurries and harder to store. Yet further, anchors with circular plates and circular shafts are more difficult to manufacture given that any offset of the shaft from dead center on the circular plate can dramatically affect performance of the anchor. For instance, when the circular plate is coupled to the shaft at a location offset from dead center, the loading within the anchor may create high loading conditions in the precast concrete structure which can incur cracking in the concrete. Non-circular components are easier to align and install relative to each other.

Further aspects of the invention are provided by one or more of the following embodiments:

Embodiment 1. An anchor for lifting precast concrete, the anchor comprising: a shaft defining a first end, a second end, and a longitudinal axis; and a circular plate coupled to the second end of the shaft, the circular plate oriented perpendicular to the longitudinal axis, wherein the shaft defines an opening extending from the first end of the shaft towards the second end of the shaft in a direction generally parallel with the longitudinal axis, the opening having a sidewall with a helical thread.

Embodiment 2. The anchor of embodiment 1, wherein the circular plate is welded to the shaft.

Embodiment 3. The anchor of any one of embodiments 1 or 2, wherein the circular plate has a circularity of at least 0.95.

Embodiment 4. The anchor of any one of embodiments 1 to 3, wherein the shaft defines a height H and the opening defines a depth D, as measured from the first end of the shaft to a bottom wall of the opening, and wherein D is in a range between 0.25 H and 1.0 H.

Embodiment 5. The anchor of any one of embodiments 1 to 4, wherein the opening comprises a bottom wall spaced apart from the first end of the shaft, and wherein the helical thread extends from the first end of the shaft to a location adjacent to the bottom wall of the opening.

Embodiment 6. The anchor of any one of embodiments 1 to 5, wherein a diameter of the shaft is constant between the first and second ends of the shaft.

Embodiment 7. A precast concrete structure comprising: a concrete body; an anchor comprising: a shaft defining a first end and a second end and a longitudinal axis; and a circular plate coupled to the second end of the shaft, the circular plate oriented perpendicular to the longitudinal axis, wherein the shaft defines an opening extending from the first end towards the second end in a direction generally parallel with the longitudinal axis, the opening having a sidewall with a helical thread, wherein the circular plate is embedded in the concrete body and the shaft extends from the concrete body such that the opening is exposed from the concrete body.

Embodiment 8. The precast concrete structure of embodiment 7, further comprising: a threaded insert comprising a threaded shank extending at least partially into the opening of the anchor and coupled to the helical thread; and a fixture coupled to the concrete body by way of the threaded insert.

Embodiment 9. The precast concrete structure of any one of embodiments 7 or 8, wherein the concrete body comprises a metal mesh and a low-density member, wherein the metal mesh comprises a plurality of openings, and wherein the anchor is disposed in the concrete body such that the circular plate is disposed between the metal mesh and the low-density member, the shaft extends through one opening of the plurality of openings, and the entire circular plate is disposed within a perimeter of the one opening when viewed in a direction parallel to the longitudinal axis.

Embodiment 10. The precast concrete structure of any one of embodiments 7 to 9, wherein the shaft has a single-piece construction, and wherein the circular plate is welded to the second end of the shaft.

Embodiment 11. The precast concrete structure of any one of embodiments 7 to 10, wherein the circular plate has a circularity of at least 0.95.

Embodiment 12. The precast concrete structure of any one of embodiments 7 to 11, wherein the shaft defines a height H and the opening defines a depth D, as measured from the first end of the shaft to a bottom wall of the opening, and wherein D is in a range between 0.2 H and 1.0 H.

Embodiment 13. The precast concrete structure of any one of embodiments 7 to 12, wherein the opening comprises a bottom wall spaced apart from the first end of the shaft, and wherein the helical thread extends from the first end of the shaft towards the bottom wall of the opening.

Embodiment 14. The precast concrete structure of any one of embodiments 7 to 13, wherein a diameter of the shaft is constant between the first and second ends of the shaft.

Embodiment 15. The precast concrete structure of any one of embodiments 7 to 14, wherein the circular plate has an area that is at least 90% of an area of a hypothetical circle circumscribing the circular plate.

Embodiment 16. A method of installing a precast concrete structure, the method comprising: threading an insert into an opening of an anchor, the anchor partially embedded in a precast concrete structure, wherein the anchor comprises a circular plate and a shaft coupled to the circular plate, wherein the circular plate is embedded in the precast concrete structure, and wherein the shaft extends from the precast concrete structure; lifting the precast concrete structure by applying tensile force to the insert; positioning the precast concrete structure; and securing a supporting fixture to the precast concrete structure by capturing a portion of the supporting fixture by a head of the insert while the insert is threaded into the opening.

Embodiment 17. The method of embodiment 16, wherein the circular plate has a circularity of at least 0.95.

Embodiment 18. The method of any one of embodiments 16 or 17, wherein the circular plate is welded to the shaft.

Embodiment 19. The method of any one of embodiments 16 to 18, further comprising removing a coil protector from the opening prior to threading the insert into the opening.

Embodiment 20. The method of any one of embodiments 16 to 19, wherein a diameter of the shaft is constant between the first and second ends of the shaft.

Embodiment 21. The method of any one of embodiments 16 to 20, wherein the anchor has an aspect ratio [D_S/D_CP] as measured by a ratio of a diameter D_S of the shaft to a diameter D_CP of the circular plate, in a range of 0.3 and 0.7.

Embodiment 22. The method of any one of embodiments 16 to 21, wherein the anchor has an aspect ratio [H/D_CP] as measured by a ratio of a height H of the shaft to a diameter D_CP of the circular plate 120, in a range of 0.5 and 2.0.

The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.