The present disclosure is directed to beam to column connections including at least one channel attached to at least one of the beam and column to facilitate the connection of the beam to the column. The channel provides a structure whose dimensions are more easily kept within relatively tight tolerance to ensure proper fit between the beam and column during erection of a building framework.
It has been found in a moment-resisting building having a structural steel framework, that most of the energy of an earthquake, or other extreme loading condition, is absorbed and dissipated, in or near the beam-to-column joints of the building.
In the structural steel construction of moment-resisting buildings, towers, and similar structures, most commonly in the past, the flanges of beams were welded to the face of columns by full-penetration, single bevel, groove welds. Thus, the joint connection was comprised of highly-restrained welds connecting a beam between successive columns. Vertical loads, that is, the weight of the floors and loads superimposed on the floors, were and still are assumed by many to be carried by vertical shear tabs or pairs of vertical, structural angle irons arranged back-to-back, bolted or welded to the web of the beam and bolted or welded to the face of the column.
The greater part of the vertical load placed upon a beam was commonly assumed to be carried by a shear tab bolted or welded to the web of the beam and bolted or welded to the face of the flange of the column at each end of the beam. Through the use of face-to-face gusset plates welded to the column, the greater part of the vertical load is carried by the gusset plates.
Experience has shown that the practice of welding the beam's flanges directly to the column is uncertain and/or unsuitable for resistance to earthquakes, explosions, tornadoes and other disastrous events. Such connection means and welding practice has resulted in sudden, fractured welds, the pulling of divots from the face of the column flange, cracks in the column flange and column web, and various other failures. Such highly-restrained welds do not provide a reliable mechanism for dissipation of earthquake energy, or other large forces, and can lead to brittle fracture of the weld and the column, particularly the flange of the column and the web of the column in the locality of the beam-to-column joint, (known as the “panel zone”).
It is desirable to achieve greater strength, ductility and joint rotational capacity in beam-to-column connections in order to make buildings less vulnerable to disastrous events. Greater connection strength, ductility and joint rotational capacity are particularly desirable in resisting sizable moments in both the lateral and the vertical plane. That is, the beam-to-column moment-resisting connections in a steel frame building can be subjected to large rotational demands in the vertical plane due to interstory lateral building drift. Engineering analysis, design and full-scale specimen testing have determined that prior steel frame connection techniques can be substantially improved by strengthening the beam-to-column connection in a way which better resists and withstands the sizable beam-to-column, joint rotations which are placed upon the beam and the column. That is, the beam-to-column connection must be a strong and ductile, moment-resisting connection.
Reference is made to co-assigned U.S. Pat. Nos. 5,660,017, 6,138,427, 6,516,583, and 8,205,408 (Houghton et al.) for further discussion of prior practice and the improvement of the structural connection between beams and columns through the use of gusset plates. These patents illustrate the improvements that have been manifested commercially in the construction industry by Houghton and others in side plate technology. Initially, side plate construction was introduced to greatly improve the quality of the beam-to-column connection. Further improvements included the provision of side plate technology using full length beams to achieve greater economy and to facilitate more conventional erection techniques.
In one aspect, a joint connection structure of a building framework generally comprising a column assembly including a column and a pair of gusset plates connected to the column on opposite sides of the column and extending laterally outward from the column. A beam assembly includes a beam having upper and lower flanges and an end portion received between the gusset plates. The beam assembly is bolted to the column assembly. A channel attached to one of the column and beam facilitates connection of the beam assembly to the column assembly. The channel defines an elongate slot for attaching the channel to said one of the column and beam.
In another aspect, a prefabricated column assembly generally comprises a column including a flange having side edges. A channel attached directly to the flange includes a base section and a pair of arms projecting outward from sides of the base section. The base section extends laterally past the side edges of the flange. A pair of gusset plates attached directly to the channel on opposite sides of the column extend laterally outward from the column.
In still another aspect, a prefabricated beam assembly generally comprises a beam including a flange having side edges. A channel attached directly to the flange includes a base section and a pair of arms projecting outward from sides of the base section. The base section extends laterally past the side edges of the flange.
In a further aspect of the present invention, a prefabricated column assembly generally comprises a column including a flange. First connecting members are bolted to an outer surface of the flange, and second connecting members are bolted to an inner surface of the flange. A pair of gusset plates extending laterally outward from the column. Bolts attaching the gusset plates to the first and second connecting members on opposite sides of the column.
Other features of the present invention will be in part apparent and in part pointed out hereinafter.
Corresponding reference characters indicate corresponding parts throughout the drawings.
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Additionally, at least one of the slots 27C in a channel 25C may be intentionally out of alignment with the horizontal pairs of bolt holes 26A in the associated flange 16 of the column 15 (
As can be seen from the figures, the channels 25C, rather than the column 15 itself, provide the structure for attaching the gusset plates 21 to the column 15. In particular, an outer surface of the arms 24 of the channel 25C are bolted to an inner surface of a respective gusset plate 21 by vertically spaced bolts (not shown) extending through aligned bolt holes 26A in the arms of the channel and the respective gusset plate. In the illustrated embodiment, the gusset plates 21 extend past both flanges of the column 15 in a direction parallel to the beam 19 such that they sandwich beams on two sides of the column. Thus, a channel 25C is disposed on both flanges 16 of the column 15. However, it will be understood that the column assembly 13 may include a channel 25C on only one of the flanges 16. One advantage of the channels 25C is that they can be produced to very close tolerances (i.e., a closer tolerance than the column 15) to insure that the gusset plates 21 are properly spaced from each other to allow for connection of the beam assembly 17 to the column assembly 13. This better ensures that the beam assembly 17 can be received between the gusset plates with appropriate clearance for attaching the beam assembly to the column assembly 13 at a construction site. The channels 25C may be formed as one piece of material or as many pieces fixed rigidly together at controlled spacings.
Alternatively, instead of the plurality of vertically spaced slots 27C, a column assembly 13′ of another embodiment may include a channel 25C′ having a single closed oblong radiused opening 27C′ extending along the length of the base section 22′ of the channel 25C′ (
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The channel 25A connects the gusset plates 21 to the upper flange 31 of the beam 19 when the beam is received between the gusset plates. The horizontal extension of the slots 27A accounts for variations in the lateral spacing between the two bolt holes 26A in a horizontal pair. Thus, the slots 27A ensure that the bolt holes 26A will be aligned within an opening in the channel 25A for receiving bolts to attach the channel to the beam 19. Therefore, the slots 27A provide advantages over circular bolt holes which do not forgive misalignment with the circular bolt holes 26A in the upper flange 31 of the beam 19.
Additionally, at least one of the slots 27A in the channel 25A may be intentionally out of alignment with the horizontal pairs of bolt hole pairs 26A in the upper flange 31 of the beam 19. A misaligned slot 27A may be configured to function as a yield point for the joint connection such that under an extreme load, the joint connection will fail at the channel 25A before the beam 19 or column 15. In the illustrated embodiment, aligned and misaligned slots 27A are alternately disposed along the length of the channel 25A. Accordingly, the horizontal spacing of the bolt holes 26A in the upper flange 31 generally corresponds to the horizontal distance between every other slot 27A in the channel 25A. Other arrangements and slot configurations may be used within the scope of the invention.
As can be seen from the figures, the channel 25A, rather than the beam 19 itself, provides the structure for attaching the gusset plates 21 to the beam. In particular, an outer surface of the arms 36 of the channel 25A are bolted to an inner surface of a respective gusset plate 21 by horizontally spaced bolts (not shown) extending through aligned bolt holes 26A in the arms of the channel and the respective gusset plate. Accordingly, the channel 25A provides the structure for attaching the gusset plates 21 to the beam 19. One advantage of the channel 25A is that it can be produced to very close tolerances (i.e., a closer tolerance than the beam 19) to insure that the connection points for attaching to the gusset plates 21 are properly spaced from each other to allow for connection of the beam assembly 17 to the column assembly 13. This better ensures that the beam assembly 17 can be received between the gusset plates with appropriate clearance for attaching the beam assembly to the column assembly 13 at a construction site. The channels 25A-25C can be formed from one piece of material or many pieces fixedly connected together at controlled spacings.
Alternatively, instead of the plurality of horizontally spaced slots 27A, a beam assembly 17′ of another embodiment may include a channel 25A′ having a single closed oblong radiused opening 37A′ extending along the length of the base section 34′ of the channel 25A′ (
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The channel 25B connects the gusset plates 21 to the lower flange 33 of the beam 19 when the beam is received between the gusset plates. The horizontal extension of the slots 27B accounts for variations in the lateral spacing between the two bolt holes 26A in a horizontal pair. Thus, the slots 27B ensure that the bolt holes 26A will be aligned within an opening in the channel 25B for receiving bolts to attach the channel to the beam 19. Therefore, the slots 27B provide advantages over circular bolt holes which do not forgive misalignment with the circular bolt holes 26A in the lower flange 33 of the beam 19.
Additionally, at least one of the slots 27B in the channel 25B may be intentionally out of alignment with the horizontal pairs of bolt hole pairs 26A in the lower flange 33 of the beam 19. A misaligned slot 27B may be configured to function as a yield point for the joint connection such that under an extreme load, the joint connection will fail at the channel 25B before the beam 19 or column 15. In the illustrated embodiment, aligned and misaligned slots 27B are alternately disposed along the length of the channel 25B. Accordingly, the horizontal spacing of the bolt holes 26A in the lower flange 33 generally corresponds to the horizontal distance between every other slot 27B in the channel 25B.
As can be seen from the figures, the channel 25B, rather than the beam 19 itself, provides the structure for attaching the gusset plates 21 to the beam. In particular, an outer surface of the arms 40 of the channel 25B are bolted to an inner surface of a respective gusset plate 21 by horizontally spaced bolts (not shown) extending through aligned bolt holes 26A in the arms of the channel and the respective gusset plate. Accordingly, the channel 25B provides the structure for attaching the gusset plates 21 to the beam 19. One advantage of the channel 25B is that it can be produced to very close tolerances (i.e., a closer tolerance than the beam 19) to insure that the connection points for attaching to the gusset plates 21 are properly spaced from each other to allow for connection of the beam assembly 17 to the column assembly 13. This better ensures that the beam assembly 17 can be received between the gusset plates with appropriate clearance for attaching the beam assembly to the column assembly 13 at a construction site.
Alternatively, instead of the plurality of horizontally spaced slots 27B, a beam assembly 17′ of another embodiment may include a channel 25B′ having a single closed oblong radiused opening (not shown) extending along the length of the base section 38′ of the channel 25B′ (
In all cases where the channels 25A, 25B, 25C are constructed to yield preferentially over the column 15, beam 19, and gusset plates 21, the joint connection may be repaired after a failure event occurs because the column, beam and gusset plates remain intact. More specifically, it may be possible to replace the channels 25A, 25B, 25C and restore a building to structural soundness after a catastrophic event such as an earthquake.
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The joint connection structure 111 is substantially similar to the first embodiment except the slots 27 in the channels 25A, 25b attached to the beam 19 in the first embodiment are removed and instead bolts 126 are received in aligned bolt holes 126A in the channels 125A, 125B and respective flanges 131, 133 of the beam 119 to attach the channels to the beam. Additionally, bolts 126 attach the gusset plates 121 directly to the column 115 (e.g., to a side surface of the column). Thus, the channels 25C attached to the column 15 in the first embodiment are omitted. However, as combinations of features are envisioned, the gusset plates 121 could be connected by channels (not shown) attached to faces of the column 115.
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The angle irons used in any of the embodiments described herein may be formed in a suitable manner. For example and without limitation, the angle irons may be formed by bending a flat plate, forming pieces separately and connecting them together by bolting welding or other suitable connection, and by casting the angle iron as a single piece of material with the arms and base. Casting has certain advantages in being able to precisely control the dimensions and relative positions of the base parts of the angle iron for additional accuracy in making the joint connection. The angle irons may also be formed as fabricated plate sections.
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The channels used in any of the embodiments described herein may be formed in a suitable manner. For example and without limitation, the channels may be formed by bending arms up from a flat plate, forming the arms and base separately and attaching the arms to the base by bolting welding or other suitable connection, and by casting the channel as a single piece of material with the arms and base. Casting has certain advantages in being able to precisely control the dimensions and relative positions of the base and arms for additional accuracy in making the joint connection. The channels and connecting members may also be formed as fabricated plate sections.
Other joint connection structures are disclosed in co-assigned U.S. Pat. No. 9,091,065, the entirety of which is herein incorporated by reference.
AA. A joint connection structure of a building framework comprising:
a column assembly including a column having a web and flanges on opposite sides of the web;
a column channel attached to the column and located between the flanges;
a beam assembly including a beam;
first and second beam channels, each of the first and second beam channels comprising a base section, arms projecting outward from opposite edges of the beam section, and a channel tab projecting from the base section at an end of the base section; the first and second beam channels being directly connected to the beam;
wherein the channel tab and column channel are directly attached to a flange of the column.
AB. The joint connection structure of AA further comprising bolts extending through the column channel, the column flange and the channel tab of one of the first and second beam channels.
BA. A joint connection structure of a building framework comprising:
a tubular column;
gusset plates bolted to the column on opposite sides thereof;
a gusset plate connector member bolted to the gusset plates;
a beam;
a beam connector bolted to the beam and bolted to the gusset plate connector to attach the beam to the gusset plates.
When introducing elements of the present invention or the one or more embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As various changes could be made in the above apparatuses, systems, and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
The present application claims the benefit of, and priority to, U.S. Provisional Application Ser. No. 62/934,967, which was filed Nov. 13, 2019, the entirety of which is incorporated herein by reference for all purposes.
Number | Date | Country | |
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62934967 | Nov 2019 | US |