Note: Descriptions are shown in the official language in which they were submitted.
CA 02654720 2009-02-18
TOP-CHORD BEARING WOODEN JOIST AND METHOD
FIELD OF THE APPLICATION
[0001] The present application relates to wooden
joists and, more particularly, to a wooden joist used in
a top-chord bearing configuration.
BACKGROUND OF THE ART
[0002] Wooden joists are horizontal supporting members
that run from wall to wall, wall to beam, or beam to beam
to support a ceiling, roof or floor. Wooden joists have
a pair of horizontal chords, interrelated by a board in
an I-joist configuration, or by V-shaped webs, in an
open-joist or truss configuration.
[0003] When wooden joists are transversely connected
to beams, metal hangers are used to interrelate the
joists to the beams. Hangers are brackets that are
secured to the beam, and that define a U-shaped so as to
support an end of a joist. Hangers are costly items, and
require a non-negligible amount of skilled manpower to
use.
[0004] Some wooden joists are used in a top-chord
bearing configuration. In this configuration, the top
chord has an extension projecting beyond the bottom chord
at an end of the j oist . The extension is seated on top
of a beam, when the joist is transversely positioned on a
beam. As all-wooden joists typically use an adhesive
between the chords and the wooden webs/board, all-wooden
joists are not used in a top-chord bearing configuration.
The top-chord bearing configuration is used with open
joists in which the webs are metal, or in open joists in
which metal square plates interface the wooden webs to
the chords. Both these open joists are relatively
expensive as they use numerous metal components.
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SUMMARY OF THE APPLICATION
[0005] It is therefore an aim of the present
application to provide a novel wooden joist for use in a
top-chord bearing configuration.
[0006] It is a further aim of the present application
to a method for adapting a wooden joist to a top-chord
bearing configuration.
[0007] Therefore, in accordance with the present
application, there is provided a wooden joist comprising:
a wooden top chord; a wooden bottom chord; wooden boards
adhesively connected to the wooden top chord and to the
wooden bottom chord to form an I-joist section along a
portion of the wooden joist; wooden webs adhesively
connected to the wooden top chord and to the wooden
bottom chord to form an open-joist section along another
portion of the wooden joist; a bearing extension defined
by the wooden top chord extending beyond any one of the
wooden boards and the wooden webs at an end of the wooden
joist; at least a pair of metal webs in alignment on
opposed 'sides of the wooden joist, each metal web
comprising a top connector end fixed to the bearing
extension, a bottom connector end fixed to the bottom
chord, and a structural arm between the connector ends,
the metal webs being solely provided in an end region
along the wooden joist; whereby the wooden joist is
adapted to be in a top-chord bearing relation with a beam
by the bearing extension and the top connector ends being
on top of the beam.
[0008] Further in accordance with the present
application, there is provided a method for adapting a
wooden joist to a top-chord bearing configuration,
comprising: providing a joist having a wooden top chord
and a wooden bottom chord adhesively connected to wooden
boards to form a joist having at least an I-joist
portion; cutting an end of the I-joist section as a
function of a required length of the wooden joist in such
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a way that a bearing extension is defined by the top
chord extending beyond the wooden boards at an end of the
I-joist; securing metal webs on opposed sides of the
wooden joist such that the metal webs are connected to
the bearing extension; whereby the joist may be used in a
top-chord bearing relation with a beam.
[0009] Still further in accordance with the present
application, there is provided a wooden joist comprising:
a wooden bottom chord; wooden boards adhesively connected
to the wooden bottom chord so as to project upwardly
therefrom; a wooden top chord adhesively connected to a
top edge of the wooden boards to form an I-joist section
with the wooden bottom chord and the wooden boards, the
wooden top chord extending beyond the wooden boards at an
end of the wooden joist to form a bearing extension; and
at least a pair of metal webs in alignment on opposed
sides of the I-joist, each metal web comprising a top
connector end fixed to the bearing extension, a bottom
connector end fixed to the bottom chord, and a structural
arm between the connector ends, the metal webs being
solely provided in an end region along the I-joist;
whereby the wooden joist is adapted to be in a top-chord
bearing relation with a beam by the bearing extension and
the connector ends being on top of the beam.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Fig. 1 is a perspective view of a wooden joist
in accordance with an embodiment, in a.top-chord bearing
relation with a beam, on an I-joist section;
[0011] Fig. 2 is an enlarged perspective view of the
wooden joist of Fig. 1, with an end in a bottom-chord
bearing configuration;
[0012] Fig. 3 is an enlarged perspective view of the
wooden joist of Fig. 1, with an end in a top-chord
bearing relation with a beam;
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[0013] Fig. 4 is an enlarged elevation view of the end
of the wooden joist of Fig. 2;
[0014] Fig. 5 is an enlarged elevation view of the end
of the wooden joist of Fig. 3;
[0015] Fig. 6 is an enlarged elevation view of an end
of the wooden joist of Fig. 1, with a removed I-joist
section;
[0016] Fig. 7 is an enlarged elevation view of an end
of the wooden joist of Fig. 1, with pairs of metal webs
forming a V;
[0017] Fig. 8 is an enlarged elevation view of an end
of the wooden joist of Fig. 1, with pairs of metal webs
forming a V and with a removed I-joist section;
[0018] Fig. 9 is a perspective view of a wooden joist
in accordance with another embodiment, in a top-chord
bearing relation with a beam, on an open-joist section;
[0019] Fig. 10 is an enlarged perspective view of the
wooden joist of Fig. 9, with an end in a bottom-chord
bearing configuration;
[0020] Fig. 11 is an enlarged perspective view of the
wooden joist of Fig. 9, with an end in a top-chord
bearing relation with a beam;
[0021] Fig. 12 is an enlarged elevation view of the
end of the wooden joist of Fig. 10;
[0022] Fig. 13 is an enlarged view of the end of the
wooden joist of Fig. 11, with pairs of metal webs forming
a V;
[0023] Fig. 14 is an enlarged view of the end of the
wooden joist of Fig. 11, with pairs of metal webs in a
parallel relation; and
[0024] Fig. 15 is a perspective view of a wooden
I-joist in accordance with yet another embodiment, in a
top-chord bearing relation with a beam.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] Referring to the drawings and more particularly
to Fig. 1, a wooden joist in accordance with an
embodiment of the present disclosure is generally shown
at 10. The wooden joist 10 has a top chord 12 and a
bottom chord 14. The top chord 12 and the bottom chord
14 are elongated lumber pieces, interconnected in a
parallel relation by wooden webs 16 in an open-joist
section 18, and a board 20 in an I-joist section 22.
[0026] In the open-joist section 18, the wooden webs
16 form a series of Vs, and are connected to the chords
12 and 14 using adhesives, as well as complementary joint
portions (e.g., scarf joints) between the webs 16 and the
chords 12 and 14. The section 18 is said to be open, as
the gaps between the wooden webs 16 can be used as a
passage for pipes, ventilation ducts, wires and the like,
in the ceiling or below the floor.
[0027] In the I-joist section 22, the board 20
interconnects the chords 12 and 14. The board/boards 20
may be received in channels defined in the chords 12 and
14, with an adhesive used to mechanically connect the
board/boards 20 to the chords 12 and 14. Moreover,
complementary joint portions, such as scarf joints or the
like, may be used to increase the contact area between
the chords 12 and 14 and the board 20. The board 20 may
be made of different types of wood panels, such as
oriented strand board (i.e., OSB), plywood, or the like.
[0028] Wooden columns 24 are also provided between the
chords 12 and 14. One wooden column 24 is at the
junction between the wooden webs 16 and the board 20.
Another wooden column 24 is at an end of the wooden joist
10, on the side of the open joist.
[0029] Referring concurrently to Figs. 2 and 4, a
ribbon 26 (aka, a 2 x 4 ribbon or a 2 x 4 band) is
optionally provided at an end of the wooden joist 10, in
a clearance in the top chord 12 and wooden column 24.
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The ribbon 26 is used for the lateral support of the
wooden joist 10, when supported in a bottom-chord bearing
configuration, on a structure A.
[0030] Referring concurrently to Figs. 1, 3 and 5, the
top chord 12 is shown projecting beyond the end of the
bottom chord 14 and the end of the board 20. The
projection is referred to as bearing extension 28. The
bearing extension 28 is seated on an upper surface of a
beam B, in a top-chord bearing relation between the
wooden joist 10 and the beam B. However, in order to
respect the structural integrity of the wooden joist 10,
metal webs 30 are added to the wooden joist 10, in the
vicinity of the bearing extension 28.
[0031] The metal webs 30 each have an arm 32 at the
ends of which are connector ends 34. The connectors ends
34 have a plurality of teeth, whereby the connector ends
34 pressed on the lateral surfaces of the chords 12 and
14 are firmly secured thereto. When the metal webs 30
are secured to the wooden joist 10 as illustrated in
Figs. 1, 3 and 5, the arm 32 is in an oblique relation
with respect to the chords 12 and 14. The metal webs 30
come in pairs, with a web 30 on each side of the wooden
joist 10, whereby only one of the pair of webs 30 is
shown in Figs. 1, 3 and 5.
[0032] Accordingly, the metal webs 30 reinforce the
wooden joists 10. The metal webs 30 are connected to the
wooden joist 10 such that the upper connector ends 34 are
on the bearing extension 28. By having the upper
connection ends 34 on the bearing extension, a part of
the load on the bottom chord 14 is supported by the beam
B through the metal web 30.
[0033] The I-joist section 22 of the wooden joist 10
is provided to adjust the overall length of the wooden
joist 10. The I-joist section 22 may be reduced in
length, by removing an end thereof. Referring to Fig. 6,
a removed portion of the I-joist section 22 is
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illustrated at 22'. The removed portion 22' is typically
sawn off, forming a cut that is perpendicular to the
longitudinal axes of the top chord 12 and bottom chord
14. However, in order to use the wooden joist 10 in a
top-chord bearing arrangement, a bearing extension 28 is
kept when cutting off an end of the I-joist section 22.
[0034] The removal of an end of the I-joist section 22
is preferably performed in plant, according to the length
required by a customer. Once a portion has been removed,
the metal webs 30 are pressed onto the wooden joist 10.
As is shown in Fig. 6, the connector end 34 on the top
chord 12 is on the bearing extension 28.
[0035] Referring to Fig. 7, a second pair of metal
webs 30 (one of which is shown, as the other is on the
hidden side) may be pressed onto the wooden joist 10 to
form a pair of Vs, so as to increase the support between
the top chord 12 and the bottom chord 14. This
configuration may be selected for longer wooden joists
10, or in view of particular uses in which the wooden
joist 10 is subjected to higher loads while in top-chord
bearing support on the beam B. As shown in Fig. 7, the
Vs of metal webs 30 may be in the I-joist section 22 of
the wooden joist 10. Alternatively, as shown in Fig. 8,
the Vs of metal webs 30 may overlap between the open-
joist section 18 and the I-joist section 22.
[0036] Referring to Fig. 9, a wooden joist in
accordance with another embodiment of the present
disclosure is generally shown at 50. The wooden joist 50
is similar in construction to the wooden joist 10 of
Figs. 1 to 8, whereby like components bear like reference
numerals. However, despite the similarities, the wooden
joist 50 of Fig. 9 is in top-chord bearing relation with
the beam B from the end of the open-joist section 18.
Referring to Figs. 11 and 12, the bearing extension 28
extends beyond a top end of one of the wooden webs 18.
The top connector ends 34 of the metal webs 30 are on the
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bearing extension 28, whereby the top connector ends 34
are on top of the beam B when the wooden joist 50 is in
top-chord bearing relation with the beam B.
[0037] Referring to Fig. 10, the I-joist section 22 is
in a bottom-chord bearing relation with the structure A.
The length of the I-joist section 22 may be reduced so as
to obtain a wooden joist of selected length. The wooden
joist 50 may be sectioned on site.
[0038] Referring to Figs. 13 and 14, additional metal
webs 30 may be used to reinforce the structural
connection between the top chord 12 and the bottom chord
14. In Fig. 13, two pairs of metal webs 30 (on opposed
sides of the wooden joist 50) are arranged to form a
V-shaped structure. In Fig. 14, two pairs of metal webs
30 (on opposed sides of the wooden joist 50) are arranged
to have the metal webs 30 of the same side in a parallel
relation. Both these configurations increase the contact
area between connector ends 34 of the metal webs 30 and
the chords 12 and 14, thereby structurally reinforcing
the wooden joist 50.
[0039] Referring to Fig. 15, a wooden joist in
accordance with yet another embodiment is generally shown
at 60. The wooden joist 60 is similar in construction to
the wooden joist 10 of Figs. 1 to 8, whereby like
components bear like reference numerals.
[0040] The wooden joist 60 does not have an open-joist
section. Accordingly, the joist 60 has wooden boards 20
on its full length. The wooden joist 60 has a bearing
extension 28 at one of its ends, whereby the wooden joist
60 may be installed in a top-chord bearing relation with
a beam B. In order to adjust its length, the opposite
end of the wooden joist 60 may be sectioned. The
sectioning may be performed on site or off site.
[0041] By having the use of metal webs 30 limited to
the end of the wooden joists 10, 50 and 60, these wooden
joists have a limited amount of metal components, thereby
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reducing their cost. The metal webs 30 structurally
reinforce the joist 10, 50 and 60, by providing an
additional amount of retention between the chords 12 and
14 (i.e., tensile strength) This additional amount of
retention adds to that provided by the adhesive
connection between the chords 12 and 14. Accordingly, by
the presence of the metal webs 30, the stiffness and
damping of the wooden joists 10, 50 and 60 are increased.
It is pointed out that metal webs 30 can be provided at
both ends of the wooden joists 10, 50 and 60, so as to
have the wooden joists 10, 50 and/or 60 supported in top-
chord bearing on both ends.
[0042] As a non-limitative example, the wooden joists
10, 50 and 60 typically have a span of 8 to 30 feet. The
metal web 30 covers approximately 1 foot of span, and a
pair of webs 30 combined in a V-shape (e.g., Fig. 7)
spans on 2 feet. The metal webs 30 are in the end region
of the joists so as to cover between 5 to 150 of the end
of the joist in terms of span. Configurations in which
more than a pair of metal webs 30 are used are typically
for longer spans of wooden joist.
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