This invention relates to a structural connector for attaching two structural members together in a structure such as a building, the structural connector having a two-tiered embossment formed in at least one of the members of the connector to strengthen the connector.
The structural connector of the present invention has particular application in the field of structural hangers where an elongated, generally horizontally disposed structural member is hung from a supporting structure, both being part of the structural frame of a building.
In light frame construction, it is common to hang the joists supporting the floors of the building from horizontally disposed members often called headers, beams or ledgers. The joists can be supported by hangers which are attached to the headers, beams or ledgers. One type of hanger used is called a top flange hanger. A top flange hanger has a portion or member that rests on the top surface of the supporting structure, increasing the strength of the connection.
Unfortunately, the presence of the top flange can interfere with the setting of the sub-flooring members on top of the joists and the headers and ledgers. The top flanges create an unevenness in the surface upon which the sub-flooring is installed.
Preferably, the flat top surfaces of the joists, headers and ledgers will all be uniformly level and set at the same elevation, once the members are set in place, although deviations are often made to allow for shrinkage of members made from wood or having wood sub-components. Also, preferably, the sub-flooring used is made up of large sheets of relatively thin planar material, such as plywood or oriented strand board, that can be laid down on the level top surfaces of the headers and ledgers resulting in a uniformly flat surface for laying down the flooring.
Thus, it is desirable to minimize the thickness of any members, such as fasteners, fastener heads or hanger components that will project above the level of the top surfaces of the ledges, headers and joists. When such members project above the ultimate top level of the structural members of the flooring, they create unevenness in the surface for the subflooring, commonly known as reveal problems.
Thus, when top flange hangers are used, it is desirable to make the material of the top flange as thin as possible. However, the top flange must still be strong enough to carry the desired loads imposed on the hanger. One means of strengthening the top flanges of hangers is to create embossments or deformations in the top flange hanger that extend into the back members of the hangers. The problem with typical strengthening deformations or embossments is that too much of the material of the top flange is deformed to too great a height, thus creating reveal problems.
The present invention provides a strengthening embossment made in a first member or flange of a structural connector, where along the length of the embossment, the embossment is stepped so that it extends to different heights from the member from which it is formed to create progressive or differentiated stiffening along the member.
The present invention also provides a strengthening embossment made in a pair of first and second members or flanges of a structural connector, where the first and second members are joined at a bend line and the strengthening embossment extends from one member to the second member through the bend, and along the length of the embossment, the embossment is stepped so that it extends to different heights from at least one of the members from which it is formed.
A structural connector made according to the present invention has a substantially thin, first flange which has a top surface that has at least a portion that is substantially planar. The first flange is in operative connection with a first structural member such that forces imposed on the first flange can be transmitted to the first structural member. A structural connector made according to the present invention also has a first member that is in operative connection with a second structural member and the first flange such that forces imposed on the second structural member are transmitted to the first member, and through the first member and then to the first flange, and through the first flange to the first structural member. The first flange is integrally connected to and differentiated from the first member at a first bend between the first flange and the first member. A structural connector made according to the present invention has an embossment in the first flange that extends through the first bend into the first member, and the embossment in the first flange is formed with first and second sections, the first section generally extending uniformly to a first level above the top surface of the substantially planar first flange, that is different from a level to which the second section generally uniformly extends, the first and second sections being joined to each other at a distinct transition portion where the embossment descends from the level of the first section to the level of the second section. It is preferable that the transition portion be abrupt so that the first section sharply descends to the level of the second section. This makes the transition section easily visible which allows parts to be checked to make sure that the deep section extends far enough to provide sufficient rigidity to the part, but does not extend too far to create reveal problems.
It is a specific object of the present invention to provide a structural hanger for supporting a structural member from a supporting member, where the structural hanger is made with a top flange that rests on the top surface of the supporting member, and the top flange of the hanger is formed with strengthening deformations that increase the strength of the structural hanger while minimizing the profile of the top flange of the hanger.
It is a further object of the present invention to provide a structural hanger for supporting a structural member from a supporting member, where the structural hanger is made with a pair of top flanges that rest on the top surface of the supporting member, and the top flanges of the hanger are formed with strengthening deformations that increase the strength of the structural hanger while minimizing the profile of the top flanges of the hanger.
It is a further object of the present invention to provide that the level of the first section of the embossment of the structural connector is higher above the top surface of the first flange than the level of the second section of the embossment, and the higher first level is closer to the bend between the first flange and the first member than the second section. The inventors have found embossments which are taller near the edge of the first structural member or supporting structural member and then decrease in height but continue to extend a substantial distance along the top flange, can provide sufficient strength to structural hangers made from light gauge steal, while providing minimal interference with the laying of the subflooring.
It is a further object of the present invention to provide a top flange hanger with a two-tiered or stepped embossment that strengthens the top flange and extends the length of the top flange or substantially the length of the top flange.
It is a further object of the present invention to provide a connector that is attached to the structural members it connects with headed fasteners such as nails or bolts, and when connected using those fasteners, the shanks of the fasteners are received by the connector and the structural members and the heads of the fasteners interface with and against the connector, and in the portions of the connector that also have the two-tiered embossment of the present invention the top surfaces of the heads of the fasteners do not extend substantially above, and preferably are at the same level or below, the highest level of the deepest section of the embossments of the present invention.
A further object of the present invention is to provide a top flange hanger with low-profile strengthening deformations in its top flange or flanges that can be formed from sheet steel material on a fully automated die press with no secondary or final bend operations being necessary.
It is a further object of the present invention to provide a top flange hanger made from galvanized sheet steel or stainless steel that does not need to be welded, and, therefore, does not need to be painted to protect the hanger from corrosion.
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In the preferred form of the invention, the side members 8 and 9 interface with the substantially vertically disposed side faces 30 of the second, supported structural member 4.
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Other alternate embodiments of the invention are possible where the structural hanger 5 is formed with only a single back member that is connected to one or both of the side members 8 and 9. In the preferred embodiment, the back members 10 and 11 are disposed away from the seat 7 with respect to the side members 8 and 9, but the back members 10 and 11 could be bent inwardly of the side members 8 and 9 and be disposed above the seat 7.
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Other alternate embodiments of the invention are possible where the structural hanger 5 is formed with only a single top flange that is connected to one or both of the back members 10 and 11. In the preferred embodiment, the top flanges 12 and 13 are disposed away from the seat 7 with respect to the side members 8 and 9, but the top flanges 12 and 13 could be bent inwardly of the side members 8 and 9 and be disposed more in-line with the seat 7.
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In the preferred form of the invention, the top surface 2 and the front face 3 of the supporting member 1 are disposed orthogonally to each other. Thus, in the preferred form of the invention, the top portions of the back members 10 and 11 of the hanger 5 are disposed orthogonally to the top flanges 12 and 13 of the hanger 5. In the preferred form of the hanger 5, the top flanges 12 and 13 are joined to the back members 10 and 11 at first and second bends 14 and 15 that are tight radius orthogonal bends.
In order to enhance the rigidity of the structural hanger 5 at the first and second bends 14 and 15, first and second embossments 16 and 17 are formed in the material of the first and second back members 10 and 11 and the first and second top flanges 12 and 13 that extend through the first and second bends 14 and 15. The embossments 16 and 17 stiffen the bends 14 and 15 between the top flanges 12 and 13 and the back members 10 and 11, preventing flexing at the bends 14 and 15 which could result in movement of the supported member 4 or joist.
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The top flange portions of the embossments 16 and 17 are each formed with two distinct sections, a deep or first section 19 and a shallow or second section 20 that are connected to each other. Each section 19 or 20 is formed by deforming the material of the top flanges 12 or 13 to a generally uniform height or level above the top surfaces 28 or 29 of the top flanges 12 or 13. The sections 19 and 20 are divided by an abrupt transition area 27 where the level of the deep or first section 19 quickly descends to the level of the shallow or second section 20, creating two tiers or steps.
The deep sections 19, provide greater stiffening of the top flanges 12 and 13, since the material of the top flanges 12 and 13 is deformed to a greater extent. In the preferred embodiment, the material of the top flanges 12 and 13, used to make the deep sections 19 of the embossments 16 and 17, is displaced 1.5 times the material thickness of the part. Similarly, in the preferred embodiment, the material of the top flanges 12 and 13, used to make the shallow sections 20, is displaced 0.5 times the material thickness of the part.
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The embossments 16 and 17 are preferably between ⅜ to ¼ inches wide, and preferably multiple embossments 16 or 17 are provided in each top flange 12 or 13. This allows for appropriate spacing of the fasteners 24 between multiple embossments 16 and 17, some of which, preferably two, extend the entire length of the top flanges 12 or 13, in the relatively narrow top flanges 12 and 13 such that no fastener 24 has to be driven through an embossment 16 or 17.
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The embossments 16 and 17 are made with male punches that are received in female openings. The same male punch is used to make the top flange portions and the back member portions of each embossment 16 or 17. The same male punch machined with two different heights is also used to make the deep section 19 and the shallow section 20 of each embossment 16 or 17.
It is preferred that the corresponding female opening for each male punch be specially shaped to match the height of the shallow section 20 of each embossment 16 or 17 to prevent the material forming the embossment 16 or 17 to extend above the selected height for the shallow section 20 of the embossment 16 or 17. The female opening does not need to be so specifically manufactured for accommodating the deep section 19 of the embossment 16 or 17 to make sure it does not exceed the selected height.
By forming the top flange portions of the embossments 16 and 17 with two distinct tiers or sections, automated die press machinery can be used to create strong deep sections 19 close to the bends 14 and 15 where strength is needed, and closely controlled shallow sections 20 can be made farther away from the bends 14 and 15, where strength is less important, and minimizing the height or profile of the top flange is more important. This ensures uniformity between parts, rigidity at the bends 14 and 15 and sufficiently strong but consistently thin top flange portions near the edges 22 and 21.
When the bends 14 and 15 are formed in the blank, the male form-punch for making the bends 14 and 15 is formed with raised supports at the selected height of the back member portions of the embossments 16 and 17 and the deep sections 20 of the top flange portions of the embossments 16 and 17 to keep the embossments from collapsing around the bends 14 and 15.
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In the preferred form of the invention, at least one of the embossments 16 and 17 in each back member 10 and 11 extends below the level of the plurality of nail openings 26 near the top of the back members 10 and 11 and near the bends 14 and 15. Deflection forces are greatest around the group of fasteners 24 placed in these nail openings 26 near the top of the back members 10 and 11. In the preferred form of the invention, the plurality of nail openings 26 near the top of the back members 10 and 11 are approximately 2⅜ inches from the bends 14 and 15, but for relatively light gauge metal connectors 1 such as the preferred embodiment, the embossments 16 and 17 could extend as far as 4″ from bends 14 and 15 to strengthen the connector 1 against deflection forces at bends 14 and 15 and the fasteners 24 near the bends 14 and 15.
Some examples of materials for the supported structure 4 and the supporting structure 3 include: solid-sawn wood, engineered wood products, laminated lumber, structural composite lumber, composite I-beams, trusses, stainless steel members, and multiple ply members of the various types listed above, with the preferred materials depending on the structural requirements of the building being erected, but generally being composite I-beams for the supported structure 4 and structural composite lumber or solid sawn lumber or the supporting structure 3. When fasteners such as nails or screws are used to connect the structural hanger to the supporting member, the supporting member could be a steel I-beam with a wood nailer member attached to the top of the I-beam.
The seat 7, side members 8 and 9, back members 10 and 11, and top flange 12 and 13 may be made in a variety of sizes.
In the preferred embodiment, the structural hanger 5 will be made from 14 gauge galvanized sheet metal (approximately 0.078 inches to 0.080 inches thick depending on the type of galvanizing), but the double, two-tiered embossment of the present invention should not be limited to this particular gauge. Structural hangers made from sheet metal as thin as 20 gauge material and as thick as 7 gauge material would benefit from the two-tiered embossment of the present invention.