U.S. patent application number 16/784963 was filed with the patent office on 2020-11-12 for bolted slotted beam web connection designs.
This patent application is currently assigned to Seismic Structural Design Associates, Inc.. The applicant listed for this patent is Seismic Structural Design Associates, Inc.. Invention is credited to Clayton J. Allen, Ralph M. Richard.
Application Number | 20200354947 16/784963 |
Document ID | / |
Family ID | 1000004682659 |
Filed Date | 2020-11-12 |
United States Patent
Application |
20200354947 |
Kind Code |
A1 |
Richard; Ralph M. ; et
al. |
November 12, 2020 |
BOLTED SLOTTED BEAM WEB CONNECTION DESIGNS
Abstract
A structural steel beam-to-column field bolted connection
includes a column having a column flange and a beam. The beam
includes a first beam flange and a second beam flange. The beam
also includes a beam web extending between the first beam flange
and the second beam flange. The beam web defines at least one slot
that extends from a distal end of the beam along a length of the
beam and terminates at a stress relief hole. The connection
includes an end plate. The beam is welded to the end plate and the
end plate is bolted to the column flange.
Inventors: |
Richard; Ralph M.; (Tucson,
AZ) ; Allen; Clayton J.; (Peoria, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seismic Structural Design Associates, Inc. |
Peoria |
AZ |
US |
|
|
Assignee: |
Seismic Structural Design
Associates, Inc.
Peoria
AZ
|
Family ID: |
1000004682659 |
Appl. No.: |
16/784963 |
Filed: |
February 7, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62846252 |
May 10, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04B 1/2403 20130101;
E04B 2001/1972 20130101; E04B 2001/2448 20130101; E04B 1/19
20130101; E04C 2003/0452 20130101; E04B 2001/2457 20130101; E04B
2001/2418 20130101; E04B 2001/2466 20130101; E04C 3/02
20130101 |
International
Class: |
E04B 1/24 20060101
E04B001/24; E04B 1/19 20060101 E04B001/19; E04C 3/02 20060101
E04C003/02 |
Claims
1. A structural steel beam-to-column field bolted connection,
comprising: a column having a column flange; a beam comprising: a
first beam flange and a second beam flange; and a beam web
extending between the first beam flange and the second beam flange,
wherein the beam web defines at least one slot that extends from a
distal end of the beam along a length of the beam and terminates at
a stress relief hole; and an end plate, wherein: the beam is welded
to the end plate; and the end plate is bolted to the column
flange.
2. The structural steel beam-to-column field bolted connection of
claim 1, wherein the connection eliminates lateral torsion buckling
of the beam in a region of the connection.
3. The structural steel beam-to-column field bolted connection of
claim 1, wherein the connection provides a near uniform state of
stress and strain in the first beam flange and the second beam
flange in a region of the connection.
4. The structural steel beam-to-column field bolted connection of
claim 1, wherein the connection eliminates beam flange shear forces
in the connection.
5. The structural steel beam-to-column field bolted connection of
claim 1, wherein the connection obtains a near uniform stress
distribution across and through the first beam flange and the
second beam flange in the connection.
6. The structural steel beam-to-column field bolted connection of
claim 1, wherein the connection eliminates field welding of the
connection.
7. The structural steel beam-to-column field bolted connection of
claim 1, wherein the end plate is bolted to the column flange using
a four bolt arrangement on a top and a bottom of the end plate.
8. The structural steel beam-to-column field bolted connection of
claim 1, wherein the end plate is bolted to the column flange using
a six bolt arrangement on a top and a bottom of the end plate.
9. The structural steel beam-to-column field bolted connection of
claim 1, wherein a length of the at least one slot is determined by
the equation l.sub.s<l.sub.p+l.sub.b/10.
10. The structural steel beam-to-column field bolted connection of
claim 1, wherein the beam web define two slots that each extend
from the distal end of the beam along the length of the beam and
that each terminate at a stress relief hole.
11. The structural steel beam-to-column field bolted connection of
claim 10, wherein each slot of the two slots is approximately equal
in length.
12. The structural steel beam-to-column field bolted connection of
claim 1, wherein the first beam flange, the second beam flange, and
the beam web are each welded to the end plate.
13. The structural steel beam-to-column field bolted connection of
claim 1, wherein the stress relief hole is round and has a larger
dimension than a width of the at least one slot.
14. A method of forming a bolted slotted web beam-to-column
connection, comprising: welding an end plate onto a distal end of a
beam; and bolting the end plate to a flange of a column.
15. The method of forming a bolted slotted web beam-to-column
connection of claim 14, wherein bolting the end plate comprises
using a four bolt arrangement on a top and a bottom of the end
plate.
16. The method of forming a bolted slotted web beam-to-column
connection of claim 14, wherein bolting the end plate comprises
using a six bolt arrangement on a top and a bottom of the end
plate.
17. The method of forming a bolted slotted web beam-to-column
connection of claim 14, further comprising forming at least one
slot in a beam web of the beam, wherein the at least one slot
extends from a distal end of the beam along a length of the beam
and terminates at a stress relief hole.
18. The method of forming a bolted slotted web beam-to-column
connection of claim 17, further comprising forming a second slot in
the beam web, wherein the second slot extends from the distal end
of the beam along the length of the beam and terminates at a second
stress relief hole.
19. The method of forming a bolted slotted web beam-to-column
connection of claim 18, wherein the slot and the second slot are
approximately equal in length.
20. The method of forming a bolted slotted web beam-to-column
connection of claim 14, wherein welding the end plate onto the
distal end of the beam comprises welding a first beam flange, a
second beam flange, and a beam web onto the end plate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/846,252, entitled "BOLTED SLOTTED BEAM WEB
CONNECTION DESIGNS", filed on May 10, 2019, the entire contents of
which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] Existing beam to column connection technology oftentimes
requires welding at least a portion of the connection (such as a
portion of a beam to a portion of a column) in the field. In some
instances, due to location and/or other environmental conditions,
this can lead to problems with quality control of the weld.
Additionally, some existing beam to column connections may require
the use of a shear plate. Moreover, existing connections (such as
end plate connections) may be susceptible to undesirable lateral
torsional buckling and/or may exhibit large stress and/or strain
gradients across and through the beam flanges at the column
connection. Some known beam to column connections may also result
in larger than desirable amounts of beam shear being placed upon
flanges of the beam at the column connection. Embodiments of the
invention provide solutions to these and other issues.
BRIEF SUMMARY OF THE INVENTION
[0003] Embodiments of the present invention relate to structural
steel connections in steel moment frames that are typically made
with rolled or built-up structural shapes. The designs presented
herein combine the attributes of the design methodology and
technology of both slotted web connections and end plate
connections. The beam components of the connection that includes
the welded end plate and beam web slots can be shop prepared, while
the completed beam-to-column connection can be made by field
bolting the end plate of the slotted beam to the column flange in
the structural frame.
[0004] According to one aspect, a structural steel beam-to-column
field bolted connection is described herein. The connection may
include a column having a column flange and a beam. The beam may
include a first beam flange and a second beam flange, as well as a
beam web extending between the first beam flange and the second
beam flange. The beam web may have at least one slot adjacent to
the beam flange that extends from a distal end of the beam along a
length of the beam and may terminate at a stress relief hole. The
connection may also include an end plate. The beam may be welded to
the end plate and the end plate may be bolted to the column
flange.
[0005] According to another aspect, a method of forming a bolted
slotted web beam-to-column connection is described herein. The
method may include welding an end plate onto a distal end of a beam
and bolting the end plate to a flange of a column.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] A further understanding of the nature and advantages of
various embodiments may be realized by reference to the following
figures.
[0007] FIG. 1A depicts a side view of a bolted slotted web
connection using a four bolt arrangement according to
embodiments.
[0008] FIG. 1B depicts a front view of the bolted slotted web
connection of FIG. 1A.
[0009] FIG. 2A depicts a side view of a bolted slotted web
connection using a six bolt arrangement according to
embodiments.
[0010] FIG. 2B a front view of the bolted slotted web connection of
FIG. 2A.
[0011] FIG. 3A illustrates the force distribution in a bolted
slotted web connection in accordance with the present
invention.
[0012] FIG. 3B is a section view of the beam of FIG. 3A.
[0013] FIG. 4 is a flowchart depicting a process for forming a
bolted slotted web connection in accordance with the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The ensuing description provides exemplary embodiments only,
and is not intended to limit the scope, applicability or
configuration of the disclosure. Rather, the ensuing description of
the embodiments will provide those skilled in the art with an
enabling description for implementing multiple embodiments. It will
be understood that various changes may be made in the function and
arrangement of elements without departing from the spirit and scope
of this disclosure.
[0015] The Bolted Slotted Web (BSW) connections described herein is
a bolted steel beam-to-steel column connection that utilizing
attributes of end plate (EP) and slotted web (SW) beam-to-column
connections. In some embodiments of BSW moment connections, slots
may be formed in a beam web such that the slots are parallel and
adjacent to the flanges of the beam. These slots, which start at
the end of the beam and are typically one third to one half the
nominal beam depth in length and are typically one eighth to one
quarter inch in width, are terminated at a round stress relief hole
with a radius greater than the slot width. The beam flanges and web
are welded to an end plate which is field bolted to the column
flange to form a beam-to-column moment connection that has both
seismic and wind applications.
[0016] The embodiments of the present invention relate to
structural steel connections in steel moment frames made typically
with rolled or built up structural shapes. The connection design
presented herein utilizes attributes of slotted web and end plate
connections as described herein. The beam components of the
connection that include the welded end plate and beam web slots are
shop prepared. The completed beam-to-column connection in the
structural frame is made by field bolting the end plate to the
column flange. By separating the beam flanges with slots in the web
in the region of the connection to the column, essentially all the
beam shear is resisted by the beam web and a portion of the beam
moment at the connection. The slots eliminate lateral torsional
buckling of the beam at the connection as well as the beam flange
shear. These attributes result in near uniform stress and strain
gradients across and through the beam flanges which increases the
connection fatigue life.
[0017] Such BSW connections provide numerous advantages over
existing EP and SW connection designs. For example, BSW connections
in accordance with the present disclosure eliminate the lateral
torsional mode of beam buckling at the connection that may be
experienced in EP connections. This attribute is important for
perimeter beams that support the exterior cladding of the building.
BSW connections also eliminate the need to weld the beam flanges
and the beam web to a column flange as needed with SW connections.
In fact, the presently disclosed BSW connections may eliminate the
need for most or all field welds, as most or all of the welding may
be done in the shop where higher quality control are more easily
maintained. Additionally, BSW connections in accordance with the
present disclosure eliminate the need for a shear plate required
for SW connections, and may eliminate large stress and strain
gradients across and through beam flanges as well as a large
component of beam shear in the beam flanges that are associated
with EP connections. Rather, in the BSW connections described
herein, the beam flanges essentially resist only moment loads or
forces.
[0018] Turning now to FIGS. 1A and 1B, one example of a four bolt
BSW connection is illustrated. BSW connection uses a combination of
SW and EP connection methodology to form a bolted rigid
beam-to-column connection. As illustrated, a beam 100 may be an
I-beam or a W-beam having a top flange 102 and a bottom flange 104.
A beam web 106 extends between and connects the top flange 102 and
the bottom flange 104. The beam web 106 includes at least one slot
108 that extends along a length of the beam 102 at positions
proximate the top flange 102 and/or bottom flange 104. The beam web
106 more commonly includes a pair of slots 108 that are positioned
on opposing sides of the beam web 106 adjacent the top flange 102
and the bottom flange 104 as illustrated in FIG. 1A. The slots 108
may be formed (such as by thermal cutting) at a distal end of the
beam 100 and extend between about one third to one half of a
nominal beam depth in length, although other lengths of slots 108
may be utilized. As illustrated in FIG. 3A, in some embodiments a
length of the slots 108 may be determined by
l.sub.s<l.sub.p+l.sub.b/10 based upon the web hinge length (A-B)
and typically l.sub.s<d.sub.beam/2, where d.sub.beam is the beam
depth, l.sub.s is the slot length, l.sub.p is the plate length, and
l.sub.b is a clear span of the beam/2. Each slot 108 may terminate
in a round stress relief hole 110 that has a larger diameter than a
width of the slot 108. In FIG. 3A, h represents the story
height.
[0019] A column 112 includes a first flange 114 and a second flange
116, as well as a column web 118 that extends between and connects
the first flange 114 and the second flange 116. In the BSW
connection, the beam 100 is shown with the beam web 106 being
secured to the second flange 116 of the column 112 via an end plate
120 that is positioned between the distal end of the beam 100 and
the second flange 116 of the column 112. The distal end of the beam
100 is secured to the end plate 120 via one or more welds, such as
a fillet weld, a complete joint penetration weld, a partial joint
penetration weld, and/or other weld formed at the distal end of the
beam web 106, first flange 102 and/or second flange 104. Any weld
may be formed within a shop before the beam is transported to the
field for installation.
[0020] The end plate 120 and beam 100 is secured to the column 112
by bolting or otherwise fastening the end plate 120 to the second
flange 116 of the column 112. As shown here, four bolts 122 are
used to secure both the top and bottom of the end plate 120 to the
second flange 116 of the column 112 so that a total of eight bolts
are used to secure the beam 100 to the column 112 as shown in FIG.
1B. Specifically, a bolt 122 is positioned on each side of the beam
web 106 on both an interior side and exterior side of the first
flange 102 so that the four bolts 122 form a generally rectangular
arrangement. Four bolts are similarly oriented with respect to the
beam web 106 and second flange 104 in a generally rectangular
arrangement. The strength and position of the pre-tensioned bolts
122 and/or the end plate 120 dimensions may be determined using
existing strength and placement standards, such as those provided
by the American Institute of Steel Construction (AISC) design
guides.
[0021] In some embodiments, BSW connections may need to be able to
handle larger beam web shear forces. In such embodiments, a six
bolt BSW connection may be used, such as that illustrated in FIGS.
2A and 2B. The six bolt connection may be formed in a similar
manner to the connection described in FIGS. 1A and 1B, but may
include two additional bolts 222 that are positioned on the
interior side of the top flange 202 and bottom flange 204. For
example, as illustrated in FIGS. 2A and 2B, a single bolt 222 is
positioned on an exterior side of the top flange 202 and on each
side of the beam web 206 while a pair of bolts 222 is positioned on
an interior side of the top flange 202 and on each side of the beam
web 206. Thus, six bolts are used to secure the end plate 220 to
the column near the top flange 202. Similarly, a single bolt 222 is
positioned on an exterior side of the bottom flange 204 and on each
side of the beam web 206 while a pair of bolts 222 is positioned on
an interior side of the bottom flange 204 and on each side of the
beam web 206. Thus, six bolts are also used to secure the end plate
220 to the column near the bottom flange 204. Twelve bolts are used
in all to attached the beam 200 to the column.
[0022] While the embodiments herein are described using four and
six bolt arrangements, it will be appreciated that other numbers of
bolts may be used based on the load requirements of a particular
application. Additionally, while show in generally rectangular
arrangements, other bolt arrangements may be possible.
[0023] Returning to FIG. 3A, the force distributions in a BSW
connection are illustrated for a cantilever beam model subjected to
an ultimate end load, P.sub.u. The end load P.sub.u may be computed
from the following equation in which l.sub.b and l.sub.p are
previously defined, Z.sub.b is the beam plastic modulus, and Fy is
the beam material yield strength:
P.sub.u=Z.sub.bF.sub.y/[l.sub.b-l.sub.p]
FIG. 3B is a section view of the beam of FIG. 3A. As illustrated in
FIG. 3B, the beam flange forces in the region of the connection,
shown as tension T and compression C, are uniform from the outboard
end of the slots to the end plate. The beam web moments M.sub.A,web
and M.sub.B,web and the beam web shears V.sub.A and V.sub.B are
also illustrated in FIG. 3B. The relation between the cantilever
beam load P.sub.u and these forces and moments is determined by the
following equations:
V.sub.A=V.sub.B=P.sub.u
T=C=F.sub.yA.sub.flg
M.sub.A,web=M.sub.B,web+P.sub.ux[l.sub.s-l.sub.p]
M.sub.A,flg=M.sub.B,flg+Tx[d.sub.beam-t.sub.flg]
In the following equations, A.sub.flg is the area of the respective
flange, M.sub.A,flg and M.sub.B,flg are the flange moments,
t.sub.flg is the beam flange thickness. Beam slot lengths depend
upon both beam properties and the moment frame geometry using
slotted beam web technology as shown, for example, in FIGS. 1A, 1B,
2A, and 2B. The inelastic region in this connection as shown occurs
from end of the beam slots to the end plate at the flange of the
column. The centroid of the "beam plastic hinge", includes the beam
flanges and the beam web as shown, is one half the length of the
slots from the face of the column.
[0024] FIG. 4 is a flowchart of a process 400 for forming a bolted
slotted web beam-to-column connection. Process 400 may be used to
form any of the BSW connections described herein. At block 402, an
end plate is welded to a distal end of a beam. This welding may be
done in a shop setting so as to maintain the high quality control
standards. At block 404, the end plate (and beam) are bolted onto a
column flange. In some embodiments, a four or six bolt arrangement
may be utilized, such as those arrangements described in
conjunction with FIGS. 1A-2B.
[0025] It should be noted that the systems and devices discussed
above are intended merely to be examples. It must be stressed that
various embodiments may omit, substitute, or add various procedures
or components as appropriate. Also, features described with respect
to certain embodiments may be combined in various other
embodiments. Different aspects and elements of the embodiments may
be combined in a similar manner. Also, it should be emphasized that
technology evolves and, thus, many of the elements are examples and
should not be interpreted to limit the scope of the invention.
[0026] Specific details are given in the description to provide a
thorough understanding of the embodiments. However, it will be
understood by one of ordinary skill in the art that the embodiments
may be practiced without these specific details. For example,
well-known structures and techniques have been shown without
unnecessary detail in order to avoid obscuring the embodiments.
This description provides example embodiments only, and is not
intended to limit the scope, applicability, or configuration of the
invention. Rather, the preceding description of the embodiments
will provide those skilled in the art with an enabling description
for implementing embodiments of the invention. Various changes may
be made in the function and arrangement of elements without
departing from the spirit and scope of the invention.
[0027] The methods, systems, devices, graphs, and tables discussed
above are examples. Various configurations may omit, substitute, or
add various procedures or components as appropriate. For instance,
in alternative configurations, the methods may be performed in an
order different from that described, and/or various stages may be
added, omitted, and/or combined. Also, features described with
respect to certain configurations may be combined in various other
configurations. Different aspects and elements of the
configurations may be combined in a similar manner. Also,
technology evolves and, thus, many of the elements are examples and
do not limit the scope of the disclosure or claims. Additionally,
the techniques discussed herein may provide differing results with
different types of context awareness classifiers.
[0028] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly or conventionally
understood. As used herein, the articles "a" and "an" refer to one
or to more than one (i.e., to at least one) of the grammatical
object of the article. By way of example, "an element" means one
element or more than one element. "About" and/or "approximately" as
used herein when referring to a measurable value such as an amount,
a temporal duration, and the like, encompasses variations of
.+-.20% or .+-.10%, .+-.5%, or +0.1% from the specified value, as
such variations are appropriate to in the context of the systems,
devices, circuits, methods, and other implementations described
herein. "Substantially" as used herein when referring to a
measurable value such as an amount, a temporal duration, a physical
attribute (such as frequency), and the like, also encompasses
variations of .+-.20% or .+-.10%, .+-.5%, or +0.1% from the
specified value, as such variations are appropriate to in the
context of the systems, devices, circuits, methods, and other
implementations described herein. As used herein, including in the
claims, "and" as used in a list of items prefaced by "at least one
of" or "one or more of" indicates that any combination of the
listed items may be used. For example, a list of "at least one of
A, B, and C" includes any of the combinations A or B or C or AB or
AC or BC and/or ABC (i.e., A and B and C). Furthermore, to the
extent more than one occurrence or use of the items A, B, or C is
possible, multiple uses of A, B, and/or C may form part of the
contemplated combinations. For example, a list of "at least one of
A, B, and C" may also include AA, AAB, AAA, BB, etc.
[0029] Having described several embodiments, it will be recognized
by those of skill in the art that various modifications,
alternative constructions, and equivalents may be used without
departing from the spirit of the invention. For example, the above
elements may merely be a component of a larger system, wherein
other rules may take precedence over or otherwise modify the
application of the invention. Also, a number of steps may be
undertaken before, during, or after the above elements are
considered. Accordingly, the above description should not be taken
as limiting the scope of the invention.
[0030] Also, the words "comprise", "comprising", "contains",
"containing", "include", "including", and "includes", when used in
this specification and in the following claims, are intended to
specify the presence of stated features, integers, components, or
steps, but they do not preclude the presence or addition of one or
more other features, integers, components, steps, acts, or
groups.
* * * * *