US20140020321A1

US20140020321A1 - Precast concrete slab connector

Info

Publication number: US20140020321A1
Application number: US13/979,883
Authority: US
Inventors: Wesley K. Eklund; Gary Roberts; Tom Gerst; Sidney E. Francies
Original assignee: Fleet Engineers Inc
Current assignee: Fleet Engineers Inc
Priority date: 2011-01-18
Filing date: 2012-01-17
Publication date: 2014-01-23
Also published as: WO2012099879A2; WO2012099879A3

Abstract

A precast concrete slab connector for connecting two adjacent slabs in edge-by-edge juxtaposition, each with a recess in registry with a recess in and an adjacent slab. A pair of anchor plates are positioned the slab recesses and a shear plate spans the slabs recesses and overlies the anchor plates. The shear plate has openings that are in registry with one of an anchor plate opening. Multiple fasteners are extend through the openings in the anchor plates and the shear plates and include removable retainers that clamp the shear plates and the anchor plates together. The fasteners can be cast in part into each adjacent slab. Serration can be provided with facing surfaces of the anchor plates and the shear plate or on facing surfaces of the shear plate and washers that are mounted on the fastener.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application No. 61/433,751, filed Jan. 18, 2011, and U.S. Provisional Patent Application No. 61/537,211, filed Sep. 21, 2011, both of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a connector for adjoining adjacent precast concrete slabs or wall panels together or to a structural member of a building. Portions of the connector are embedded in the concrete wall at the time the slab is cast.
2. Description of the Related Art
Precast concrete wall panels, sometimes referred to as concrete slabs, are widely used in the building construction industry. Generally, the wall panels are manufactured at a remote facility and then shipped to the job site and erected. Once erected, connectors are used to mount the wall panels to the structural framework of the building or to attach one wall panel to another. There are many designs and materials used for these connectors, and the connectors can be pre- or post-installed. A connector may be attached to a concrete wall panel, usually by bolting it to the concrete. However, often the connectors are embedded in the concrete panels during the casting process. The exposed edges of the opposing components of the connector are then welded together to connect the erected wall panels. The metal components are commonly called weldments, weld plates, or flange connectors.
Opposing connectors often do not align perfectly with one another, so a lug or rod is welded between the connectors, instead of directly welding the connectors together. The lug or rod is welded to each connector, thereby taking up any misalignment. Using this method, at least two welds must be made at each of the multiple connections between the wall panels.

SUMMARY OF THE INVENTION

According to the invention, precast concrete slab connector for connecting two adjacent slabs in edge-by-edge juxtaposition and each of the slabs has a recess formed adjacent a recess adjacent a corresponding recess in the adjacent slab to form a recess that spans both adjacent slabs. The connector comprises a pair of anchor plates that each have at least one opening and that each is configured to be positioned within one of the slab recesses; a shear plate that has at least two openings and that is configured to span the slabs recesses and overlie the anchor plates; wherein the shear plate at least two openings are configured so that one of the at least two openings can be in registry with one of the anchor plate openings when the anchor plates are positioned within the slab recess, and multiple fasteners configured to project through the openings in anchor plates and the shear plates. The fasteners include removable retainers that are configured to clamp the shear plates and the anchor plates together and thereby bind the slabs together.
In one embodiment, the fasteners are configured to be cast in part into the slab recess.
In one embodiment, the fasteners comprise bolts and nuts and the retainers comprise the nuts that are threadable onto the bolts. Other fasteners such as shafts and threadless retainers can also be used.
In a preferred embodiment, the anchor plates can be identical.
The shear plate openings can be formed by at least one set of slots that are perpendicular to each other. Preferably the shear plate openings are formed by two sets of slots that are perpendicular to each other.
In one embodiment, the shear plate and the anchor plates have facing serrations that interlock with each other. The serrations may take the form of pyramids or may take the form of ridges and valleys.
In another embodiment, the shear plate can have serrations on a surface thereof and washers with interlocking serrations can be configured to be positioned on the surface of the shear plate in registry with the shear plate serrations. The serrations on the washers are on a surface that faces serrations on the surface of the shear plate. The washers can be mounted on the fasteners and the fasteners can clamp the washers to the shear plate. Further, the serrations on the shear plate can be positioned adjacent the slots for interfacing with the serrations on the washers. In addition, the serrations can be formed by parallel rows of ridges and valleys.
Further according to the invention, a connecting joint is formed between two concrete slabs having a recess spanning the two slabs, the connecting joint comprising a connector according any of the foregoing embodiments.
Still further according to the invention, a connecting joint is formed between two concrete slabs having a recess spanning the two slabs, the recess having a portion of the recess in each of the two concrete slabs. The connecting joint comprises an anchor plate mounted in each of portions of the recess with bolts have shafts that extend through openings in the anchor plate; a shear plate spans both portions of the recess and is mounted to each of the anchor plates though the bolts and with nuts fastened onto the bolts.
In one embodiment, the bolts are cast in part into the respective slab.
In one embodiment, the shear plate has at least one set of slots that are perpendicular to each other. Preferably, shear plate has two sets of slots that are perpendicular to each other.
In addition, the shear plate and the anchor plates can have facing serrations that interlock with each other. Alternately, the shear plate have serrations on an upper surface thereof and washers can be mounted on the bolts between the fasteners and the shear plate, wherein the washers can have on the undersurface thereof serrations which mate with the serrations on the upper surface of the shear plate. The serrations may take the form of pyramids or may take the form of ridges and valleys. In addition, the serrations on the shear plate can be positioned adjacent the slots for interfacing with the serrations on the washers.
In a preferred embodiment, there are multiple bolts connecting each anchor plate and the shear plate.
According to the invention, the joints are free from welds between the anchor plates and the shear plate.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a front perspective view of two precast concrete slabs juxtaposed at side edges thereof and illustrating a connector assembly according one embodiment of the invention.

FIG. 2 is a plan view of an anchor plate of the connector assembly illustrated in FIG. 1.

FIG. 3 is a plan view of a shear plate of the connector assembly illustrated in FIG. 1.

FIG. 4 is an enlarged perspective view of a portion of the anchor plate within the circle IV of FIG. 2.

FIG. 5 is an exploded view of the connector assembly illustrated in FIG. 1.

FIG. 6 is a top perspective view of the connector assembly illustrated in FIG. 1.

FIG. 7 is a bottom perspective view of the connector assembly illustrated in FIG. 1.

FIG. 8 is a perspective view of a connector assembly according to a second embodiment of the invention.

FIG. 9 is a bottom perspective view of a washer used in the connector assembly shown in FIG. 8.

FIG. 10 is an exploded perspective view of the connector assembly shown in FIG. 8.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, and in particular to FIG. 1, two cast concrete slabs X and Y are illustrated in edge-by-edge juxtaposition. A pocket 60 is formed in the junction of the front or rear face and side edges of each slab X and Y to form a recess 60 for mounting connectors, as is known in the art. A connector assembly 10 according to the invention is mounted in the recess and comprises two anchor plates 12 and a shear plate 14. The anchor plates 12 and shear plate 14 are generally flat, rectangular members made of structural steel, and can be galvanized to prevent corrosion. The anchor plates 12 and shear plate 14 can be formed from heavy metal stock using any suitable metal working processes, including stamping and machining. The anchor plates 12 are identical and are adapted to be embedded in adjacent concrete slabs X and Y while they are being cast, but in a mirror image orientation with respect to each other. The pocket 60 is formed by simply placing a rubber or foam block (not shown) over the anchor plates 12 during casting, as is also commonly known in the art. The foam block also prevents concrete from flowing onto the upper surface of the anchor plate 12.
Referring to FIG. 2, each anchor plate 12 comprises a main body 16 and a pair of legs 18. The main body 16 is substantially rectangular and has a leading edge 20 and an interior edge 22. Additionally, the main body 16 comprises at least one circular hole 24 formed therethrough. In the illustrated example, the main body has two circular holes 24, which are located closer to the leading edge 20 than to the interior edge 22.
The legs 18 extend from the main body 16. The legs 18 are positioned at the sides of the main body 16, near the interior edge 22, and together with the main body 16, form two shoulders 26.
Referring to FIG. 3, the shear plate 14 comprises a generally rectangular main body 30 having two portions, A and B. Although the main body 30 is described as being made up of two portions, the main body 30 is a single, undivided member.
The main body 30 further comprises a plurality of slots formed therethrough. As can be seen in the illustrated example, portion A includes two slots 32 and portion B includes two additional slots 34. The pairs of slots 32, 34 are oriented perpendicular to one another.
The connector 10 further comprises a plurality of adjustable fasteners, such as a commonly known threaded bolt 40 and nut 42 (see FIG. 5).
Referring now to FIG. 4, the upper surface of each of the anchor plates 12 is formed of a uniform array of pyramidal shaped projections 50 that extend outward from the surface and are arranged in a uniformly spaced, bi-directional geometric pattern. In addition, the lower surface of the shear plate 14 is formed with an identical uniform array of pyramidal shaped projections 50 that extend outward from the surface and are arranged in a uniformly spaced, bi-directional geometric pattern. When placed together, the projections 50 on the anchor plate 12 mate with the projections on the shear plate 14.
Referring back to FIG. 1, the anchor plates 12 and bolts 20 are embedded into the slabs X and Y at the time of casting, in a manner well known in the art. Prior to the casting process the anchor plates 12 and bolts 40 are positioned within a mold and held in place with wooden or plastic forms. The foam blocks or voids as they are known are mounted in place on the wooden or plastic forms, leaving the surface and projections 50 free for the installation of the shear plate 14. The foam block is sized to leave at least a portion of the main body 16, including the holes 24, exposed, while the remainder of the anchor plate 12, including the legs 18, is embedded in the concrete. Additionally, the heads of the bolts 20 are embedded in the cast concrete. Embedding a portion of the main body 16, the legs 18, and the bolts 20 into the slab X, Y creates a very strong bond between the slab X, Y and the anchor plate 12. It is within the scope of the invention to cast the slabs X,Y so that the bolts are not embedded in the slabs.
The anchor plate 12 is positioned within the slab X, Y and the pocket 60 such that the leading edge 20 is coextensive with the edge of the slab X, Y and no portion of the anchor plate 12 is located outside the pocket 60.
After the slabs X, Y have been cast and sufficiently hardened, the foam blocks are removed. The pocket 60 is open on at least the front face and the edge of the slabs. As can be seen in the illustration in FIG. 1, the pocket 60 is open along one face of the slab X, Y and along the side edges of the slabs X and Y. Positioning the pocket 60 along other edges of the slab X, Y is also possible, for example, the top or bottom edges, or the exterior face.
In use, the slabs X and Y are erected and placed edge-to-edge juxtaposition. With the side edges of the slabs X and Y adjacent one another, the halves of the pocket 60 and anchor plates 12 are also aligned. The shear plate 14 can then be installed over the ends of the exposed bolts 20 through the openings formed by the pocket 60. The slots 32, 34 on the shear plate 14 are aligned with the bolts 20, and nuts 42 are installed on the bolts 20 and torqued down to attach the shear plate 14 to the anchor plates 12, as illustrated in FIGS. 6 and 7.
The slots 32, 34 in the shear plate 14 provide a mechanism to adjust the position of the shear plate 14 relative to the bolts 20 and anchor plates 12 so as to accommodate any misalignment between the adjacent slabs X and Y. Misalignment can be accommodated along the length of the slots 32, 34 in both the up/down direction and left/right direction, relative to the orientation of the connector 10 in FIG. 1.
Additionally, the projections 50 described above greatly strengthen the connection between the anchor plates 12 and the shear plate 14, essentially locking the shear plate 14 to the anchor plates 12. The projections 50 of the shear plate 14 and anchor plates 12 mate and nest together, providing great strength for the joint formed thereby. Further, the projections 50 also enable the adjustability described above. Due to their relatively small size and the large number of projections 50, fine adjustment between the anchor plates 12 and shear plate 14 is possible.
If readjustment is needed, it is a simple matter of loosening the nuts 42, adjusting the position of the shear plate 14, and re-tightening the nuts 42.
The connector 10 described above provides for quick and easy connection between to precast concrete wall panels or slabs. The connector 10 enables some misalignment between wall panels also, and even allows simple and easy realignment if needed. Additionally, the connector 10 does not require welding, as required by many of the prior art connectors. Welding the joint between two wall panels takes time and labor and does not allow for any adjustability, as the connector 10 of the invention does.
Referring to FIGS. 8-10, where like numerals are used to indicate like parts, a second and preferred embodiment of the invention comprises a connector assembly 70 adapted to be mounted the recess 60 shown in FIG. 1. The connector assembly 70 comprises two anchor plates 72 and a shear plate 74. The anchor plates 72 and shear plate 74 are generally flat, rectangular members made of structural steel sheet of, for example, ¼ inch rolled sheet stock, and can be galvanized to prevent corrosion. The anchor plates 72 are identical and are adapted to be embedded in adjacent concrete slabs X and Y (FIG. 1) while they are being cast, but in a mirror image orientation with respect to each other.
Each anchor plate 72 comprises a main body 76 and a pair of legs 78. The main body 16 is substantially rectangular and has a leading edge 80 and an interior edge 82. Additionally, the main body 76 comprises at least one circular through hole 84. In the illustrated example, the main body has two circular through holes 84, which are located closer to the leading edge 80 than to the interior edge 82. Both faces of the anchor plates 72 are flat and without machining.
The legs 78 extend from the main body 76. The legs 78 are positioned at the sides of the main body 76, near the interior edge 82, and together with the main body 76, form two shoulders 86.
The shear plate 74 is generally rectangular main having opposite end portions A and B. As can be seen in the illustrated example, portion A includes two elongated slots 90 arranged along a longitudinal direction and portion B includes two additional longitudinal slots 92 arranged along a transverse direction with respect to the elongated slots 90. Thus, the pairs of slots 90, 92 are oriented perpendicular to one another. The upper surface 88 of the shear plate 74 has serrations 96 machined in an elongated rectangular pattern around each of the elongated slots 90 and 92. The serrations are in the form of elongated, parallel ridges and valleys. Each of the serrations extends transverse to the longitudinal axes of the elongated slots. The machined serrations are machined into the upper surface 88 of the shear plate. The serrations can be any suitable depth, for example, 0.075 in. in a ¼ in. plate. The serrations can form any suitable pattern but a typical pattern as shown in the drawings can be parallel ridges that are spaced, for example, 0.15 in., cut at an angle, for example, of about 90 degrees between the ridges. The type and dimensions of pattern can vary over a wide range to achieve the desired connector requirements without departing from the invention. The underside of the shear plate 74 (not shown) is plain and unmachined.
The connector 70 further comprises a plurality of adjustable fasteners, such as commonly known threaded bolts 40 that extend though the holes 84 in the anchor plates 27 and through the slots 90 and 92 in the shear plate 74 and nuts 42 that are threaded onto the bolts.
Unlike the first embodiment of the invention, the upper surface of each of the anchor plates 12 is plain and unmachined. Likewise the underside (not shown) of the anchor plate 72 is also plain and unmachined. However, in this embodiment, a washer 94 having through hole 98 has on its undersurface serrations 96 that mate with the serrations 96 on the shear plate 74. Typically, the serrations on the washer 94 are identical to the serrations on the shear plate 74. The use of the serrations 96 only adjacent to the slots of the shear plate significantly reduces the machining required to lock the anchor plates 72 to the shear plate 74.
In use, as in the previous embodiment, the anchor plates 72 and bolts 20 are embedded into the slabs X and Y (FIG. 1) at the time of casting, in a manner well known in the art. Prior to the casting process the anchor plates 72 and bolts 40 are positioned within a mold and held in place with wooden or plastic forms. The foam blocks or voids as they are known are mounted in place on the wooden or plastic forms, leaving the surface free for the installation of the shear plate 74. The foam block is sized to leave at least a portion of the main body 76, including the holes 84, exposed, while the remainder of the anchor plate 72, including the legs 78, is embedded in the concrete. Additionally, the heads of the bolts 20 are embedded in the cast concrete. Embedding a portion of the main body 76, the legs 78, and the bolts 20 into the slab X, Y creates a very strong bond between the slab X, Y and the anchor plate 72. It is within the scope of the invention to cast the slabs with the legs 78 embedded in the slabs and the bolts resting in the recesses but not within the slabs.
The anchor plate 72 is positioned within the slab X, Y and the pocket 60 such that the leading edge 80 is coextensive with the edge of the slab X, Y and no portion of the anchor plate 72 is located outside the pocket 60.
After the slabs X, Y have been cast and sufficiently hardened, the foam blocks are removed. The pocket 60 is open on at least the front face and the edge of the slabs. As can be seen in the illustration in FIG. 1, the pocket 60 is open along one face of the slab X, Y and along the side edges of the slabs X and Y. Positioning the pocket 60 along other edges of the slab X, Y is also possible, for example, the top or bottom edges, or the exterior face.
In use, the slabs X and Y are erected and placed edge-to-edge juxtaposition. With the side edges of the slabs X and Y adjacent one another, the halves of the pocket 60 and anchor plates 72 are also aligned. The shear plate 74 can then be installed over the ends of the exposed bolts 20 through the openings formed by the pocket 60. The slots 90, 92 on the shear plate 74 are aligned with the bolts 20, and washers 94 and nuts 42 are installed on the bolts 20 and torqued down to attach the shear plate 74 to the anchor plates 72, as illustrated in FIG. 8.
The slots 90, 92 in the shear plate 74 provide a mechanism to adjust the position of the shear plate 74 relative to the bolts 20 and anchor plates 72 so as to accommodate any misalignment between the adjacent slabs X and Y. Misalignment can be accommodated along the length of the slots 90, 92 in both the up/down direction and left/right direction, relative to the orientation of the connector 70 in FIG. 1.
Additionally, the serrations 96 described above greatly strengthen the connection between the anchor plates 72 and the shear plate 74, essentially locking the shear plate 74 to the anchor plates 72. The serrations 96 of the shear plate 74 and washers 94 mate and nest together, providing great strength for the joint formed thereby. Due to their relatively small size, fine adjustment between the anchor plates 72 and shear plate 74 is possible.
If readjustment is needed, it is a simple matter of loosening the nuts 42 and washers 94, adjusting the position of the shear plate 74, and re-tightening the nuts 42.
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims.

Claims

What is claimed is:

1. A precast concrete slab connector for connecting two adjacent slabs in edge by edge juxtaposition and each of the slabs has a recess formed adjacent a corresponding recess in the adjacent slab to form a recess that spans both adjacent slabs, the connector comprising:

a pair of anchor plates that each have at least one opening and each of which is configured to be positioned within one of the slab recesses;

a shear plate that has at least two openings and that is configured to span the slabs recesses and overlie the anchor plates; wherein the shear plate has at least two openings that are configured so that one of the at least two openings can be in registry with one of the anchor plate openings when the anchor plates are positioned within the slab recess, wherein the shear plate openings are formed by at least one set of slots that are perpendicular to each other; and

multiple fasteners configured to project through the openings in anchor plates and the shear plates, and the fasteners are configured pass through the anchor plate openings and the shear plate openings to clamp the shear plates and the anchor plates together and thereby bind the slabs together.

2. The precast concrete slab connector according to claim 1 wherein the fasteners comprise threaded bolts and nuts and the retainers comprise the nuts that are threadable onto the bolts and are configured to be cast in part into each adjacent slab.

3. The precast concrete slab connector according to claim 2 wherein the anchor plates are identical.

4. (canceled)

5. The precast concrete slab connector according to claim 1 wherein the shear plate and the anchor plates have facing serrations that interlock with each other.

6. The precast concrete slab connector according to claim 5 wherein the serrations take the form of pyramids.

7. The precast concrete slab connector according to claim 1 wherein the shear plate has serrations on an upper surface thereof and further comprising washers that are configured to be positioned on the surface of the shear plate in registry with the shear plate serrations, and the washers have on the undersurface thereof serrations which mate with the serrations on the upper surface of the shear plate.

8. The precast concrete slab connector according to claim 7 wherein the washers are mounted on the fasteners and the fasteners clamp the washers to the shear plate.

9. The precast concrete slab connector according to claim 8 wherein the serrations on the shear plate are positioned adjacent the slots for interfacing with the serrations on the washers.

10. The precast concrete slab connector according to claim 7 wherein the serrations are formed by parallel rows of ridges and valleys.

11. A connecting joint between two concrete slabs having a recess spanning the two slabs, the connecting joint comprising a connector according to claim 1 mounted in the recess, wherein the anchor plates are anchored into their respective slabs, and the fasteners extend through the anchor plate openings and the shear plate openings and clamp the shear plates and the anchor plates together and thereby bind the slabs together.

12. The connecting joint between two concrete slabs according to claim 11 wherein the fasteners are with nuts fastened onto the bolts.

13. (canceled)

14. The connecting joint between two concrete slabs according to claim 12 wherein the shear plate and the anchor plates have facing serrations that interlock with each other.

15. The connecting joint between two concrete slabs according to claim 14 wherein the serrations take the form of pyramids.

16. The connecting joint between two concrete slabs according to claim 12 wherein there are multiple bolts connecting each anchor plate and the shear plate.

17. The connecting joint between two concrete slabs according to claim 12 wherein the joints are free from welds between the anchor plates and the shear plate.

18. The connecting joint between two concrete slabs according to claim 12 wherein the shear plate has serrations on an upper surface thereof and further comprising washers mounted on the bolts between the fasteners and the shear plate, and the washers have on the undersurface thereof serrations which mate with the serrations on the upper surface of the shear plate.

19. The connecting joint between two concrete slabs according to claim 18 wherein the serrations on the shear plate are positioned adjacent the slots for interfacing with the serrations on the washers.

20. The connecting joint between two concrete slabs according to claim 19 wherein the serrations are formed by parallel rows of ridges and valleys.

21. The connecting joint between two concrete slabs according to claim 12 wherein the bolts are cast in part into a respective slab.

22. A precast concrete slab connector for connecting two adjacent slabs in edge by edge juxtaposition and each of the slabs has a recess formed adjacent a corresponding recess in the adjacent slab to form a recess that spans both adjacent slabs, the connector comprising:

a shear plate that has at least two openings and that is configured to span the slabs recesses and overlie the anchor plates; wherein the shear plate has at least two openings that are configured so that one of the at least two openings can be in registry with one of the anchor plate openings when the anchor plates are positioned within the slab recess;

wherein the shear plate and the anchor plates have facing serrations that interlock with each other; and

multiple fasteners configured to project through the openings in anchor plates and the shear plates, and the are configured pass through the anchor plate openings and the shear plate openings to clamp the shear plates and the anchor plates together and thereby bind the slabs together.

23. The precast concrete slab connector according to claim 22 wherein the serrations take the form of pyramids.

24. A precast concrete slab connector for connecting two adjacent slabs in edge by edge juxtaposition and each of the slabs has a recess formed adjacent a corresponding recess in the adjacent slab to form a recess that spans both adjacent slabs, the connector comprising:

wherein the shear plate has serrations on an upper surface thereof and further comprising washers that are configured to be positioned on the surface of the shear plate in registry with the shear plate serrations, and the washers have on the undersurface thereof serrations which mate with the serrations on the upper surface of the shear plate

25. The precast concrete slab connector according to claim 24 wherein the shear plate has serrations on an upper surface thereof and further comprising washers that are configured to be positioned on the surface of the shear plate in registry with the shear plate serrations, and the washers have on the undersurface thereof serrations which mate with the serrations on the upper surface of the shear plate.

26. The precast concrete slab connector according to claim 25 wherein the washers are mounted on the fasteners and the fasteners clamp the washers to the shear plate.

27. The precast concrete slab connector according to claim 26 wherein the serrations on the shear plate are positioned adjacent the slots for interfacing with the serrations on the washers.

28. The precast concrete slab connector according to claim 24 wherein the serrations are formed by parallel rows of ridges and valleys.