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(11) | EP 0 127 359 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Slotted insert and nut assembly |
| (57) A connector for embedding in a precast concrete wall panel to mount the panel on
a building comprising a first channel member (10) pressed from sheet steel and having
a channel with a bottom wall (14) and side walls (16), a second channel member (12)
pressed from sheet steel and having a channel with a bottom wall (20) and side walls
(22), the channel of said second channel member having a width that substantially
equals the length of the channel of the first channel member and a depth substantially
less than the depth of the first channel member, the channel of said second channel
member (12) being contained by the channel ofthe first channel member (10), the bottom
wall of the channel ofthe second channel member extending across a cross section of
the channel ofthe first channel member and the side walls (22) of the second channel
member extending upwardly to the bottom wall (14) of the first channel member whereby
to form a nut chamber at the bottom portion ofthe channel of the first channel member,
an elongated access slot for (26) the shank (46) of a bolh to said nut chamber in
the bottom wall (14) of the first channel member. |
[0001] This invention relates to a connector for connecting a precast concrete wall panel to a structural member of a building. The connector is embedded in the wall panel at the time the wall panel is cast.
[0002] Precast concrete wall panels are used extensively in the construction of buildings. The general method of construction is to assemble a structural framework for the wall and then mount the wall panelson the structure. Connectors are used for the purpose.
[0003] The connectors are embedded in the precast concrete panel and have a chamber that houses a nut or other anchor member of a securement means.
[0004] There are many designs and materials used for these anchors..They are, for example, fabricated from sheet steel by a welding process and they are cast from cast malleable iron or steel. They all meet design specifications in respect of load but they do not all do it for the same manufacturing cost. Cast connectors tend to be relatively expensive. Fabricated sheet steel anchors of the prior art tend to be expensive.
[0005] This invention relates to a connector that is made from sheet steel. U.S. Patent 4,194,333 relates to a prior steel fabricated connector of our development that has had considerable commercial success.
[0006] It is, however, a relatively expensive design to manufacture. The basic insert consists of three separately formed pieces of steel which must be structurally welded together to form the basic element of the anchor. The present invention also is made of sheet steel but the basic unit consists of only two separately formed pieces that can be simply tacked together to form the basic element of the anchor. The result is a less expensive product of equal or better holding strength.
[0007] The purpose of the invention is to provide a less expensive but equally effective sheet steel connector.
[0008] A connector for embedding in a precast concrete wall panel to mount the panel on a building comprises a first channel member pressed from sheet steel and having a channel with a bottom wall and side walls, a second channel member pressed from sheet steel and having a channel with a bottom wall and side walls, the channel of said second channel member having a width that substantially equals the length of the channel of the first channel member and a depth substantially less than the depth of the first channel member, the channel of said second channel member being contained by the channel of the first channel member, the bottom wall of the channel of the second channel member extending across a cross section of the channel of the first channel member and the side walls of the second channel member extending upwardly to the bottom wall of the first channel member whereby to form a nut chamber at the bottom portion of the channel of the first channel member, an elongated access slot for the shank of a bolt to said nut chamber in the bottom wall of the first channel member, said first channel member having a concrete anchor flange extending outwardly from the upper extremity of each of its side walls. The invention will be more clearly understood after reference to the following detailed specification read in conjunction with the drawings.
[0009] In the drawings:
Figure 1 is a perspective illustration of a connector according to the invention;
Figure 2 is an end view of Figure 1;
Figure 3 is a view of a strap anchor for use with the connector; and
Figure 4 is an illustration of the connector embedded in a precast concrete building wall panel illustrating how it can be used to mount the panel to form the wall of a building.
[0010] The connector is assembled from a channel member 10 and a channel member 12. The channel member 10 has a bottom wall 14, side walls 16 and flanges 18 which extend outwardly of the channel from the upper extremities of the side walls.
[0011] Channel member 12 similarly has a bottom wall 20, side walls 22 and flanges 24 which extend outwardly of the upper extremities of the side walls. Channel members 10 and 12 are each pressed from sheet steel.
[0012] The length of the channel member 12 is about equal to the interior width of the channel of the channel member 10 at a section between its top and bottom so that the channel member 12 can be simply inserted into the channel of channel member 10 as illustrated to form a nut chamber at the lower portion of the channel of channel member 10. It will be noted that the bottom wall 14 of channel member 10 is slotted as at 26 to provide access to the nut chamber. Tack welds 27 hold channel member 12 within channel member 10.
[0013] A nut 28 having shoulders that are embraced by the walls of the channel of channel member 10 is located in the nut chamber by means of a piece of foam plastics material. The foam plastics material extends into the thread of the bore of the nut 28 and has a length that bears against the bottom of channel 12 so as to maintain the nut against the bottom of channel 10 ready for engagement by the threaded shank of an anchor strap as will be explained. The bore in the nut is accessible through the slot 26 in the bottom of channel 10.
[0014] The two channel members are preferably stamped from hot rolled structural steel and assembled one inside the other in the relationship illustrated in Figure 1. Tack welds at locations such as 27 maintain the two members in assembled relation.
[0015] These connectors are usually galvanized to prevent corosion and with the construction it is possible to galvanize before they are assembled. This is a convenience and avoids the problem of getting the galvanizing material on the threads of the nut.
[0016] The anchor flanges 18 extend outwardly of the channel member 10. Conveniently the bottom of channel 10 has a width so that the sides of the channel cooperate with the sides of the nut 28 to prevent rotation of the nut. There is no need to make the channel of channel member 10 over sized with respect to the nut because good and sufficient anchor can be achieved with a bottom channel width only sufficient to retain a square nut for a 3/4 inch diameter bolt. A bottom channel width just slightly over 1 1/4 inches is sufficient.
[0017] A 3/4 inch bolt and nut of high strength design will safely carry an ultimate load of 20,000 pounds or 20K with the insert of this invention before engagement by a bolt in use, the nut 28 is held into a position at the bottom of channel member 10 by means of a length of foam plastics material 29 that is threaded into the threaded bore of the nut and presses against the bottom of the channel 12. So held in position, the nut 28 can be manually moved to any location along the length of the slot for access by a bolt in use.
[0018] Flanges 24 on the sides of channel 12 can be used to locate the connector in a mold prior to casting of a concrete panel.
[0019] Figure 3 illustrates a cast concrete building wall panel 38 with connectors according to the invention embedded therein. The connectors are cast into the panel at the time of casting of the panel according to well known practice. Numerals 40 and 41 refer to typical building structural members to which the wall panels are to be secured.
[0020] In use, the structural I-beams 40 have threaded studs 48 extending therefrom at about the location of the connectors. A threaded strap anchor 42 that comprises a U-shaped strip of steel 44 having a threaded shank 46 welded to and extending from its ends is caused to engaged the nut 28 of the connector. In this connection the threaded shank 46 of the strap anchor is threaded into the nut 28and the strap is slid up or down the slot of the connector until the U-shaped strip of metal overlies the anchor stud 48. It is then adjusted in position and a nut 50 is tightened over the stud bolt 48 to secure the panel with respect to the structural member 40. Numeral 47 is a shoulder nut that can be tightened against the outside bottom of the channel member 10.
[0021] Horizontal adjustment between the structural member and the wall panel is achieved by relieving the nut 50 from the stud anchor,making the adjustment and then retightening the anchor. Numeral 47 insures that nut 28 is firmly held against the bottom of channel member 10. Shims between the structural members and panel can be used. Other methods of adjustment are possible.
[0022] The threaded strap anchors 42 are preferably welded to the I-beam 40 when final adjustment has been made and stud connectors 48 are removed.
[0023] The structural member 41 is of an L-shaped design and in this case S-clips 52 of standard design are bolted to the connector by means of bolts 54 which pass through the S-clip and into the nut 28 within the connector.
[0024] In the case of either securement means, it will be apparent that the nut within the connector can be easily engaged by either the threaded shank of the strap anchor 42 or bolt 54 of S clip 52 to conveniently secure the concrete panel to a structural member. Vertical adjustment of the panel can be easily achieved as the nut 28 slides within the channel.
[0025] It has been found that there is no difficulty achieving an ultimate pull-out capacity of 20,000 pounds with the connector of this invention. The load capacity varies with the depth of the channel member 10. It has been found that with a depth of about 4 1/2 inches a connector according to this invention when embedded in 5000 p.s.i. concrete will support at least 20,000 pounds. The anchor fails in use when the concrete into which the anchor is embedded breaks away from the panel in the form of a cone.
[0026] The anchor per se when not embedded in concrete will fail at loadings substantially above 20,000 pounds. Thus, the anchor per se is substantially stronger than the concrete into which it is embedded.
1. A connector for embedding in a precast concrete wall panel to mount the panel on
a building comprising:
a first channel member pressed from sheet steel and having a channel with a bottom wall and side walls;
a second channel member pressed from sheet steel and having a channel with a bottom wall and side walls;
the channel of said second channel member having a width that substantially equals the length of the channel of the first channel member and a depth substantially less than the depth of the first channel member;
the channel of said second channel member being contained by the channel of the first channel member, the bottom wall of the channel of the second channel member extending across a cross section of the channel of the first channel member and the side walls of the second channel member extending upwardly to the bottom wall of the first channel member whereby to form a nut chamber at the bottom portion of the channel of the first channel member;
an elongated access slot for the shank of a bolt to said nut chamber in the bottom wall of the first channel member;
said first channel member having a concrete anchor flange extending outwardly from the upper extremity of each of its side walls.
2. A connector as claimed in Claim 1 in which said second channel member has securement
flanges extending outwardly from the upper extremities of its side walls.
3. A connector as claimed in Claim 1 or Claim 2 having a nut in said nut chamber;
means in the channel of the second channel member for holding said nut against the
bottom wall of the channel of said first channel member; the width of said channel
of the first channel member being about the width of said nut to restrain the nut
from rotation; the width of said access slot being adapted to expose the threaded
bore of the nut for access through the bottom wall of the first channel.
4. A connector substantially as hereinbefore described with reference to the accompanying
drawings.