Note: Descriptions are shown in the official language in which they were submitted.
CA 02510216 2005-06-20
STRUCTURAL WALL FRAMEWORK
Field of the Invention
This invention relates to a structural wall framework, to a method of
forming the framework and to a bracing unit for use in the framework.
Background of the Invention
Prefabricated wall frameworks for buildings such as houses are made by
advancing a top plate and bottom plate past a fastening station. Studs are
located between the plates and are fixed in place by a nailing or pressing
machine or the like.
As is well known, studs are arranged at predetermined spacings such as
about 450 to 600 mm in order support loads which the framework will be
subjected to when installed in a building. The studs are also required at
these
spacings to support plasterboard which will form the internal wall surface of
the
building.
In order to ensure that the framework has the required structural integrity,
the framework is braced by bracing. The bracing can take a number of farms,
including angle brace, plywood brace and wooden brace. Generally the angle
brace and wood brace needs to be cut into the framework, thereby reducing its
strength, as the framework is being prefabricated, and this greatly increases
the
time taken to form the framework and also the complexity of the manufacturing
process. Plywood braces are usually only suitable for external walls or where
brick veneer cladding is used.
Modem building designs and, in particular, domestic dwellings generally
include large window spaces. The incorporation of large window spaces in the
framework limits the amount of bracing which can be used, and therefore the
raking strength of the framework. The raking strength of the framework is the
ability of the framework to restrain horizontal shear forces which apply a
load
which tends to flatten the framework generally in the plane of the framework.
The
efFectiveness of the common forms of wall bracing diminishes significantly as
the
length of the braced section of the wall frame diminishes.
Summary of the Invention
Among the objects of a first aspect of the invention is to provide a
structural wall framework which can provide for large window spacings, yet
still
have sufficient raking strength to support required loads.
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This aspect of the invention may be said to reside in a structural wall
framework comprising a top plate, a bottom plate, and a plurality of studs
extending between the top plate and the bottom plate. The studs have a first
face and a second opposite face which are parallel to the plane of the wall
framework. Side faces join the first and second faces. At least one bracing
unit
is connected to the top plate and bottom plate, and comprised of at least two
of
said studs and separate bracing elements interconnecting the stud. Each of the
separate elements are connected to the first or second faces of the at least
two
studs. The bracing elements extend substantially all of the way from the top
plate to the bottom plate.
By providing the plurality of bracing elements which are connected to the
studs and extend between the top plate and bottom plate, the framework is
provided with the required raking strength in a smaller space than with
conventional angle brace and wooden brace. This allows large window spaces to
be formed in the framework whilst at the same time providing the required
raking
strength.
The use of a prefabricated bracing unit reduces the complexity of
manufacture of the framework because studs together with suitable bracing can
be concurrently provided in the framework. Thus, it is not necessary to
perform a
separate step of cutting in angle brace or wood brace into the framework.
Thus,
both the time taken to produce the framework and the complexity of the
manufacturing process can be reduced.
A further aspect of the invention may be said to reside in a bracing unit for
a structural wall framework. The bracing unit comprises at least two spaced
apart studs, each having a f rst face and a second face which are parallel.
Side
faces join the first and second faces. The studs have first and second ends. A
plurality of separate bracing elements are connected to the first face or
second
face of the studs and extend substantially all the way from the first end to
the
second end of the studs.
A further aspect of the invention relates to a method of forming a structural
wall framework. This aspect of the invention comprises providing a top plate
and
a bottom plate, and locating at least one prefabricated braang unit between
the
top plate and the bottom plate. The bracing unit comprises at least two studs
each having ends, the studs having a first face and a second face which are
parallel to a plane of the wall framework and side faces joining the first and
second faces, and a plurality of separate bracing elements extending
substantially all of the way from one end of the bracing unit to the other end
of
the bracing unit. The bracing unit is connected to the top plate and bottom
plate.
Thus, according to this aspect of the invention, both bracing and studs are
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incorporated into the framework in a single operation, thereby decreasing
the amount of work which is required to form the framework, and also
simplifying
the manufacturing process.
Other objects and features of the present invention will be in part apparent
and in part pointed out hereinafter.
Brief Description of the Drawings
Preferred embodiments of the invention will be described, by way of
example, with reference to the accompanying drawings, in which:
Figure 1 is a view of a bracing unit according to one embodiment of the
invention;
Figure 2 is a view of a bracing unit according to a second embodiment of
the invention;
Figure 3 is a view of a bracing element according to the preferred
embodiment of the invention;
Figure 4 is a view of a structural wall framework according to one
embodiment of the invention;
Figure 5 is a detailed view showing connection of a bracing unit to a bottom
plate of the framework; and
Figure 6 is a view along the line V-V of Figure 5.
Corresponding reference characters indicate corresponding parts
throughout the views of the drawings.
Detailed Description of the Preferred Embodiments
Figure 1 shows a bracing unit 10 according to one 30 embodiment of the
invention. The bracing unit 10 comprises spaced apart studs 12 and 14 which
have ftee ends 13 and which are connected together by a bracing system 15
which comprises discrete bracing elements 16 and 17.
In the preferred embodiment of the invention, the elements 16 comprise
metal braces sold under the name POSI-STRUT manufactured by MiTek. The
bracing element 17 comprises one half of a braang element 16. As is shown in
Figure 3 the bracing element 16 has a weakening 32 formed by partially cutting
or scoring the element 16 so the element 16 can be easily broken in half to
form
the two elements 17. The bracing elements 16 and 17 are provided with
punched teeth 31 (see Figure 3) at end plate regions 18 which penetrate into
the
studs 12 and 14 to thereby fix the bracing elements 16 and 17 to the studs 12
and 14 to form the bracing unit 10.
The bracing elements which are connected to the studs may comprise only
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bracing elements 16, only bracing elements 17, or as is shown in the
drawings, a combination of the elements 16 and 17. By using elements 16 and
17 it is more easy to provide an integral number of bracing elements which
extend all of the way from one end of the studs to the other end of the studs
with
suitable small spacings between the elements to provide as many bracing
elements as is possible from the bracing elements 16 and 17 to thereby
increase
the raking strength of the framework including the bracing unit.
In other embodiments, bracing elements of a different type to those formed
by or of the POSI-STRUT braces referred to above could be used. These include
thin strips of metal, wooden elements such as rectangular cross-section
boards.
Furthermore, the shape of the elements may be different to those referred to
above. Still further, the elements need not extend between the s#uds at acute
angles (about 45 degrees as in the preferred embodiment), but could extend at
other angles including perpendicular (i.e., horizontally) to the studs.
The vertical height of the units 10 depend on the size of the wall frame
which is being made, and the height of the units 10 may be anywhere between,
for example, 2100 mm to 2700 mm. The studs 12 and 14 may be spaced apart
by a distance between 300 and 400 mm for example. The bracing elements 16
and 17 extend substantially the full length of the studs 12 and 14 between
free
ends 13 of the studs so that when the unit 10 is arranged vertically, the
bracing
elements 16 and 17 extend all the way from an upper end of the bracing unit 10
to a lower end of the braang unit 10. The elements 16 and 17 are spaced apart,
as is required to enable a number of the bracing units 16 or 17 to be so
located.
The formation of the bracing system 15 from the discrete bracing elements
16 or 17 accommodates a greater variation in height of the frame unit by
simply
increasing the size of the gaps befinreen elements 16, 17 as is needed to
ensure
that an integral number of the units are provided to extend between the top
end
and lower end of the bracing unit 10.
A nogging 19 may be provided between the studs 12 and 14 as is shown.
Figure 2 shows a second embodiment in which a bracing unit 20 is
comprised of three studs 22, 24 and 26. As in the previous embodiment, a
braang system 25 is provided which extends from the upper end of the braang
unit 20 to the bottom end of the braang unit 20. The bracing system 25
comprises two sets 25' and 25" of discrete bracing elements 16 and 17 which
are the same as those described with reference to Figure 1. Once again, the
bracing elements 16 and 17 are spaced apart to extend all of the way between
the free ends 13 of the studs 22, 24 and 26.
As in the earlier embodiment, noggings 19 may be provided between
adjacent studs 22, 24 and 26.
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In other embodiments, the bracing unit may include four or more
studs with appropriate numbers of bracing sets interconnecting the adjacent
studs.
It should also be understood in other embodiments the bracing elements
may have a different configuration to those shown in the drawings. Whilst in
the
embodiment of Figure 2 the iwo sets of bracing elements are horizontally
aligned, the horizontal configuration is optional and the two sets of bracing
elements could be staggered with respect to one another.
The embodiment of Figure 2 provides a stronger wall frame than the
embodiment of Figure 1. Although the effective length L of the bracing unit of
Figure 2 is double the length L of the bracing unit of Figure 1 the
configuration of
Figure 2 gives more than double the strength. Thus, the embodiment of Figure 2
provides more than double the raking strength compared to the embodiment of
Figure 1 while still using relatively small components which are also used in
the
embodiment of Figure 1.
The embodiments of Figures 1 and 2 greatly increase the horizontal raking
load a wall frame using the bracing units can take, compared to an equivalent
width of a braced framework according to conventional bracing techniques.
Typically, conventional systems for bracing adjacent studs have a single brace
extending between a top of one stud to a bottom of the adjacent stud. When
studs must be spaced relatively closer together, the brace tends to become
more
nearly vertical. That leaves the brace practically ineffective in resisting
the
horizontal loads. This is not the case in the present invention which features
multiple unit braces which remain more nearly horizontal.
Typically the load which the bracing unit of Figure 2 can take is in the order
of 2.7 kN and the length L of the braang unit is in the order of 750 mm. This
compares to a conventional braced wall frame using angle iron or timber
bracing
which would require bradng of a length of in order of 1800 mm in order to
provide the same capacity. Thus, in this embodiment of the invention, the load
capacity is provided by a greatly reduced length L compared to conventional
systems, thereby increasing the amount of space which is available for a
window
without sacrificing raking strength.
Figure 4 is a view of a framework 50 according to one embodiment of the
invention. The framework 50 has a top plate 51 and a bottom plate 52. For
illustrative purposes, the bracing unit 10 described with reference to Figure
1 is
located at one end of the framework 50 and the bracing unit 20 described with
reference to Figure 2 is located at the other end. However, it should be
understood that the wall framework may include only bracing units according to
the embodiment of Figure 1, or only bracing units according to the embodiment
i
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of Figure 2, or some other combination of those two types of bracing units. A
window space 30 is defined between the bracing units 10 and 20 and the top
plate 51 and bottom plate 52. The framework 50 is formed by locating the
braang unit 10 between the plates 52. and 52 so the free ends 13 of the studs
abut respective plates 51 and 52 and securing the framework 10 to the plates
51
and 52 by fasteners, as will be described with reference to Figures 5 and 6.
Similarly, the bracing unit 20 is located at the other end of the plates 51
and 52
and secured in place.
The bottom plate 52 may be provided with tie down connectors 60 to
facilitate connection of the framework to a floor frame or concrete slab of a
building.
In the preferred embodiment of the invention, the bracing elements formed
from the POSI-STRUT braces are thin and are connected on a first face 21 of
the studs 12 so that the opposite second face 23 of the studs are left
completely
free, thereby providing a surface for location of plasterboard which is not
interfered with by bracing or the like. The first face 21 and second face 23
of the
studs are joined by side faces 27. The first face 21 of the studs is the side
of the
studs which is intent to be outermost when the framework is installed in a
building. Thus, the bracing on first face 21 of the studs is substantially
flush with
the studs and is easily accommodated within the brick cavity of an exterior
building wall.
The framework of the present invention therefore particularly lends itself to
exterior walls of a building in which window spaces are required. However, the
framework could be used as an internal wall of a building if required.
The framework shown in Figure 4 may also include individual studs 29
which are connected to the top plates 51 and 52 in the usual manner.
Typically,
a number of such conventional studs 29 are connected in the normal
manufacturing technique by advancing the top plate 51 and bottom plate 52 past
a securing station and locating the stud or studs 29 in place, and then
securing
them to the top plate 51 and bottom plate 52.
After the standalone studs 29 have been connected in place, the bracing
units 10 and 20 can be lifted into position and then secured to the top plate
51
and bottom plate 52.
Figures 5 and 6 show one method of connecting the studs of 35 the
bracing units 10 and 20 to the top plate 51 and bottom plate 52. The stand
alone
studs 29 can be connected in the same manner.
As is shown in Figures 5 and 6, the studs 12 and 14 are connected to
bottom plate 52 by a generally U-shaped strap 90 which has an arm 91 and
opposite arm 92 and a base 93. The arms 91 and 92 may be provided with
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punched teeth for penetrating the stud 12 and bottom plate 52, ormay be
provided with holes so that the arms 91 and 92 can be nailed to the stud 12
such
as by nails 33.
The other ends of the studs 12 and 14 are connected to the top plate 51
(not shown in Figures 5 and 6) in the same manner.
Thus, the studs 12 and 14 are connected to the plates 51 and 52 in the
same manner as individual studs would have been connected in the
conventional manufacturing method. However, in this embodiment of the
invention, bracing is concurrently incorporated into the framework when the
studs 12 and 14 are secured to the plates 51 and 52. Thus, in the preferred
embodiment of the invention the bracing elements 16 and 17 are connected to
the studs 12 and 14, and 22, 24 and 26 before the bracing units 10 and 20 are
attached to the top plate 51 and bottom plate 52. Therefore the braang is
provided at the same time as those studs. However, in other embodiments the
bracing elements 16 and 17 could be attached on site after the studs 12 and
14,
and 22, 24 and 26 are connected to the top plates 51 and 52.
In the preferred embodiment shown in Figures 1 and 2 the ends of the
studs 12 and 14, 22, 24 and 26 connect directly to the top plate 51 and bottom
plate 52. However, in other embodiments cross members (not shown) may be
provided at the ends 13 of the studs and the cross members may connect to the
top plate 51 and bottom plate 52.
In the claims which follow and in the preceding description of the invention,
except where the context requires otherwise due to express language or
necessary implication, the word "comprise", or variations such as "comprises"
or
"comprising°, is used in an inclusive sense, i.e. to specify the
presence of the
stated features but not to preclude the presence or addition of further
features in
various embodiments of the invention.
Since modifications within the spirit and scope of the invention may readily
be effected by persons skilled within the art, it is to be understood that
this
invention is not limited to the particular embodiment described by way of
example hereinabove.
