U.S. patent application number 13/443939 was filed with the patent office on 2012-08-02 for composite structural tie.
This patent application is currently assigned to POLYSTRAND, INC.. Invention is credited to Andrew Gordon, Benjamin Pilpel.
Application Number | 20120192523 13/443939 |
Document ID | / |
Family ID | 39674693 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120192523 |
Kind Code |
A1 |
Pilpel; Benjamin ; et
al. |
August 2, 2012 |
COMPOSITE STRUCTURAL TIE
Abstract
A structural tie 10 is made from at least one layer of composite
material 20. The composite material has a polymer matrix filled
with at least one reinforcing material. In one embodiment, the
matrix is a thermoplastic and the reinforcing material is fibers
encapsulated by the thermoplastic. A structural tie 10 may be
selectively formable, in situ, by applying heat to cause the matrix
material to soften. Once softened, the structural tie can be
conformed to an adjacent surface. The structural tie may include
layers 20, 22 of composite material bonded to one another.
Optionally, the structural tie is a hybrid of a composite material
and a metallic material bonded together. A structural tie may be
heat-bondable to a structural member 24.
Inventors: |
Pilpel; Benjamin; (Montrose,
CO) ; Gordon; Andrew; (Montrose, CO) |
Assignee: |
POLYSTRAND, INC.
Montrose
CO
|
Family ID: |
39674693 |
Appl. No.: |
13/443939 |
Filed: |
April 11, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12021434 |
Jan 29, 2008 |
|
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13443939 |
|
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60898194 |
Jan 29, 2007 |
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Current U.S.
Class: |
52/745.21 ;
52/745.19; 52/745.2 |
Current CPC
Class: |
E04B 1/2612
20130101 |
Class at
Publication: |
52/745.21 ;
52/745.19; 52/745.2 |
International
Class: |
E04B 1/38 20060101
E04B001/38; E04G 21/12 20060101 E04G021/12; E04G 21/14 20060101
E04G021/14 |
Claims
1. A method of making a structural tie, comprising: establishing a
desired orientation between at least two structural members;
heating a composite material to soften the composite material and
facilitate changing a configuration of the composite material;
forming the composite material into a customized structural tie
that conforms to the structural members in the desired orientation;
and cooling the composite material in the conformed configuration
to make the structural tie.
2. A method according to claim 1, wherein the composite material
comprises a polymeric matrix material and at least one reinforcing
material.
3. A method according to claim 2, wherein the polymeric matrix
material is a thermoplastic.
4. A method according to claim 2, wherein the at least one
reinforcing material comprises continuous fibers oriented
approximately parallel to one another.
5. A method according to claim 2, wherein the at least one
reinforcing material comprises a plurality of randomly oriented
fibers.
6. A method according to claim 1, wherein at least one layer of
metallic material is adjacent to the composite material, the
metallic material comprising steel or aluminum.
7. A method according to claim 1, further comprising: securing the
structural tie to the structural members
8. A method of conforming a structural tie to structural members to
be connected by the structural tie, the method comprising:
establishing a desired orientation between the structural members;
heating the structural tie to soften it and facilitate changing its
configuration; custom-fitting the structural tie to the structural
members in the desired configuration; and cooling the structural
tie.
9. A method according to claim 8, wherein the structural tie
comprises at least one layer of composite material.
10. A method according to claim 9, wherein the structural tie
further comprises at least one layer of metallic material adjacent
to the at least one layer of composite material, the metallic
material comprising steel or aluminum.
11. A method according to claim 9, wherein the composite material
comprises a polymeric matrix material and at least one reinforcing
material.
12. A method according to claim 11, wherein the polymeric matrix
material is a thermoplastic.
13. A method according to claim 11, wherein the at least one
reinforcing material comprises continuous fibers oriented
approximately parallel to one another.
14. A method according to claim 11, wherein the at least one
reinforcing material comprises a plurality of randomly oriented
fibers.
15. A method according to claim 8, wherein the structural tie
comprises: a first layer of composite material having a first
polymeric matrix and a first reinforcing material; and a second
layer of composite material having a second polymeric matrix
material and a second reinforcing material.
16. A method according to claim 15, wherein the first polymeric
matrix material is different from the second polymeric matrix
material.
17. A method of interconnecting structural members, comprising:
establishing a desired orientation between the structural members;
heating a structural tie to soften the structural ties and
facilitate changing a configuration of the structural tie;
custom-fitting the structural tie to the structural members in the
desired configuration to establish a custom configuration for the
structural tie; cooling the structural tie in the custom
configuration; and securing the structural tie to the structural
members.
18. A method according to claim 17, wherein the structural tie
comprises at least one layer of composite material.
19. A method according to claim 18, wherein the structural tie
further comprises at least one layer of metallic material adjacent
to the at least one layer of composite material, the metallic
material comprising steel or aluminum.
20. A method according to claim 18, wherein the composite material
comprises a polymeric matrix material and at least one reinforcing
material.
21. A method according to claim 20, wherein the polymeric matrix
material is a thermoplastic.
22. A method according to claim 20, wherein the at least one
reinforcing material comprises continuous fibers oriented
approximately parallel to one another.
23. A method according to claim 20, wherein the at least one
reinforcing material comprises a plurality of randomly oriented
fibers.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application and claims the
benefit of co-pending U.S. patent application Ser. No. 12/021,434,
filed on Jan. 29, 2008, which claims the benefit of U.S.
Provisional Application No. 60/898,194, filed Jan. 29, 2007. Both
U.S. patent application Ser. No. 12/021,434 and U.S. Provisional
Application No. 60/898,194 are hereby incorporated by reference in
their entireties herein.
FIELD OF THE INVENTION
[0002] This invention generally relates to structural ties useful
in the construction industry, and more particularly to structural
ties useful in joining together and/or supporting structural
members such as joists, posts, rafters, and the like.
BACKGROUND
[0003] Pre-formed structural ties are widely used in the
construction industry to help support and secure structural members
together. For example, in the construction of wood-framed
buildings, a type of structural tie known as a joist hanger is used
to facilitate the placement and mounting of floor or ceiling
joists. Generally, these structural ties are made from galvanized
metal and are shaped to support the structural members in
predetermined orientations.
[0004] Often, the above described structural ties are used and
exposed to harsh environments. For example, joist hangers are
typically employed to support the joists on outdoor decks. These
joist hangers are directly exposed to the prevailing weather
conditions of the particular locale in which the deck is situated.
This can be particularly detrimental if the locale is a shoreline
area where the deck and thereby the joists are exposed to salt-air,
salt-vapor or salt spray. In such an area, not only are the joist
hangers used on outdoor exposed structural members at risk,
structural ties used anywhere on a structure can be exposed to some
level of salt air and the corrosive effects attendant therewith. It
has been found in areas where exposure to salt water either
directly or via vapor, air or spray occurs, galvanized metallic
structural ties can be rendered completely ineffective due to the
resulting corrosion.
[0005] Another difficulty associated with structural ties is due to
the fact that the metal from which the ties are made is homogeneous
and exhibits essentially the same mechanical properties throughout
the entirety of the tie. While it may be possible to vary the
thickness and thereby the mechanical properties within a given tie,
the manufacturing costs for such a structural tie would become
prohibitive. Accordingly, where a situation warrants that a
structural tie exhibit strength in one load direction and ductility
in other directions, conventional structural ties cannot address
this need.
[0006] In addition to the foregoing, prior art structural ties are
available in various different configurations and are selected for
use according to the planned orientation between structural members
and the type of structural member involved. However, on building
sites, the actual orientation needed between particular structural
members often differs from what is planned. For example, the
structural members may not have the expected configuration for
which the structural tie is designed. In particular, a pre-formed
structural tie for wooden 2.times.4s that is suitable in theory may
not be suitable on site if the actual 2.times.4 is warped but is
otherwise acceptable for use. A user may attempt to use the
structural tie nonetheless, either by attempting to re-shape the
tie on-site (e.g., by physically re-bending it), by making ad-hoc
variations from the planned structural configuration, or simply by
forcing the structural tie to fit the needed orientation. All of
these solutions are problematic. Re-bending a structural tie that
is not designed to be re-bent, particularly a metal tie, is
difficult to do with precision and also weakens the tie, and
varying the planned design of a structure can weaken the structure
and lead to other construction problems. Forcing the structural tie
creates stresses in the tie that can lead to premature failure.
[0007] Yet another problem sometimes encountered with galvanized
metal ties occurs as a result of the structural tie being bent or
struck with a hammer or other implement during installation. When
this happens, the galvanized coating can be cracked or chipped off
exposing the underlying metal to the environment. The exposed metal
will corrode much more quickly than the galvanized metal resulting
in premature failure of the structural tie
[0008] Based on the foregoing, it is the general object of the
present invention to improve upon or overcome the problems and
drawbacks associated with the prior art.
SUMMARY OF THE INVENTION
[0009] The present invention resides in one aspect in a structural
tie that comprises at least one layer of composite material. The
composite material has a polymer matrix filled with at least one
reinforcing material.
[0010] In the preferred embodiment of the present invention the
polymeric matrix is a thermoplastic and the reinforcing material is
in the form of a plurality of fibers encapsulated by the
thermoplastic polymeric matrix. The fibers can be formed from
virtually any fibrous reinforcing material known to those skilled
in manufacturing composite materials, such as, but not limited to
boron, carbon, Kevlar, E-Glass and S-Glass. The fibers can be
continuous or chopped or a combination of continuous and chopped
fibers. In addition, the fibers can be oriented, e.g. parallel to
one another, or the fibers can be randomly oriented. The structural
tie can also include a combination of parallel and randomly
oriented fibers depending on the desired mechanical properties of
the structural ties. While the polymeric matrix has been described
as being formed from a thermoplastic material, the present
invention is not limited in this regard as a thermosetting material
can also be employed.
[0011] In another aspect, the present invention is directed to a
structural tie that is selectively formable, in situ, by
selectively applying heat to the structural tie thereby causing the
matrix material to soften. Once softened, the structural tie can be
moved to conform to a shape defined by an adjacent surface upon
cooling of said structural tie.
[0012] In an embodiment of the present invention, the structural
tie includes a plurality of layers of composite material bonded to
one another. Each layer of composite material will include the
polymeric matrix as well as the reinforcing material. In a
preferred embodiment of the present invention, the reinforcing
material in each of the layers is in the form of a plurality of
elongated continuous fibers arranged in a substantially parallel
relationship relative to one another. The laminated composite
material can be arranged so that the fibers in successive layers
are oriented parallel or at an angle relative to one another.
[0013] In still another embodiment of the present invention, the
composite material includes at least one first composite material
having a first polymeric matrix material and a first reinforcing
material and at least one second layer of composite material having
a second polymeric matrix material and a second reinforcing
material. At least a portion of the first and second layers of
composite material are bonded to one another. Preferably, the first
and second layers of composite material are different from one
another. This difference can manifest itself in the first and
second matrix materials being different. For example, one matrix
material can be a thermoplastic and the other matrix material can
be a thermosetting polymer. The first and second materials can also
both be thermoplastic or thermosetting polymers with the polymers
themselves being different. Similarly, the first and second
reinforcing materials may be different materials, such as but not
limited to E and S glass. In addition, the reinforcing materials
may be chopped, continuous or combinations thereof.
[0014] The present invention also resides in a structural tie that
is heat bondable to a structural member. In such an embodiment the
polymeric matrix is of such a type that can be heat bonded to the
material forming the structural member. Alternatively, a layer of
heat bondable polymer can be provided on the structural tie in an
area of the tie that will abut the structural member.
[0015] In another embodiment of the present invention, the
structural tie is a hybrid consisting of a composite material and
at least one layer of metallic material bonded to said composite
material. The metallic layer of material can be made from any
suitable material, such as, but not limited to steel, aluminum,
stainless steel, metal matrix, composites, sintered metals and the
like. The metallic layer can be encapsulated in a polymer which can
then be bonded to the structural tie. The metallic layer can also
be encapsulated by an elastomer or a composite material that is the
same as, or different from a composite material used to form the
remainder of the structural tie. The layer of metallic material can
be embedded in the structural tie, or the metallic layer can be
positioned adjacent to, or form an interior or outer layer of the
structural tie.
[0016] The metallic layers can be formed to follow the contours of
the entire structural tie, or the metallic layer can be formed and
sized so that it is selectively positionable in areas where the
mechanical properties of the metallic layer will be beneficial to
the overall integrity of the structural tie.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of an exemplary structural tie
of the present invention, shown in the illustrated embodiment as a
joist hanger.
[0018] FIG. 2 is a perspective view of the structural tie of FIG. 1
shown attached to a structural member.
[0019] FIG. 3 is a perspective view of the structural tie of FIG. 1
attached to a structural member.
[0020] FIG. 4 is a partial cross-sectional view of an embodiment of
the material from which the structural ties of the present
invention are made.
[0021] FIG. 5 is a partial cross-sectional view of an embodiment of
a structural tie showing the material configuration of the
structural tie.
[0022] FIG. 6 is a partial cross-sectional view of an embodiment of
a structural tie showing the material configuration of the
structural tie.
[0023] FIG. 7 is a partial cross-sectional view of an embodiment of
a structural tie showing the material configuration of the
structural tie.
DETAILED DESCRIPTION OF THE INVENTION
[0024] As shown in FIG. 1 a structural tie in the form of a joist
hanger is generally designated by the reference number 10. As used
herein, the term "Structural Tie" should be broadly construed to
mean components employed to aid in the positioning and retention of
at least one structural member relative to an adjacent structural
member or surface. The structural tie 10 is comprised of at least
one layer of composite material. The composite material includes a
polymeric matrix filled with at least one reinforcing material. The
joist hanger 10 is symmetric about the longitudinally extending
centerline 12 and includes an interior area 14 defined by generally
opposite side walls 16 and bottom surface 18. While a joist hanger
10 has been shown and described, the present invention is not
limited in this regard as other structural ties known to those
skilled in the pertinent art to which the present invention
pertains are also considered to form part of the present invention.
A representative sampling of the type and shape of structural ties
encompassed by the present invention are manufactured by Simpson
Strong-Tie of 5956 W. Las Positas Blvd. Pleasanton, Calif.
94588.
[0025] In an embodiment of the present invention the polymeric
matrix material is a thermoplastic, such as, but not limited to
polypropylene, polyethylene, nylon, PEI and copolymers and the
like. Because, the structural tie 10 can potentially be exposed to
extremes in temperature depending on where it is used, the
softening temperature of the thermoplastic matrix should in general
be greater than any environmentally induced temperature to which
the structural tie may be exposed in service. For example, the
thermoplastic may be selected to have a softening temperature
greater than about 50 to about 65.degree. C. (about 120 to about
150.degree. F.). Conversely, where the structural tie will be
exposed to cold temperatures it may be necessary to employ a
thermoplastic matrix material having a glass transition
temperature, e.g. the temperature where the thermoplastic becomes
brittle, that is lower than the exposure temperature. Accordingly,
it may prove necessary to use structural ties formed of different
thermoplastics depending on the environment where the structural
tie will be used. While a thermoplastic has been shown and
described, the present invention is not limited in this regard as
other polymeric materials such as, elastomers or thermosetting
polymers can be employed without departing from the broader aspects
of the present invention.
[0026] The reinforcing material forming part of the above-described
composite material used in the structural tie 10 of the present
invention can be in particulate, flake or fiber form. If in fiber
form, the fibers can be chopped or continuous and can also be
aligned or randomly oriented relative to one another. Fibers found
to be useful as reinforcing materials include, but are not limited
to, E-glass, S-glass, aramid fibers such as, inter alia, those
marketed under the tradenames Kevlar, Twaron and Technora, fibers
made from basalt, glass (ECR, A and C), ultra-high molecular weight
polyethylene, carbon (such as, but not limited to, fiber marketed
under the names Toray, Fortafil, and Zoltek), boron, silica
carbide, liquid crystal polymer (such as, but not limited to,
Vectran, metallic fibers, etc. The choice of the material to use as
a reinforcing material will depend on several factors including the
desired mechanical properties of the structural tie, and the cost
of manufacturing the structural tie.
[0027] In a preferred embodiment of the present invention, the
composite material includes fibers embedded in a polymeric matrix
(either thermoplastic or thermoset) that are continuous and aligned
relative to one another. The composite material of the present
invention can consist of a single layer of material, or it can
comprise multiple layers stacked one-on-top-of-the-other and bonded
together to form a laminate. The layers of the laminate can be
bonded to one another via an adhesive, or the polymeric matrix
material can function as the adhesive so that via the application
of pressure and/or heat the layers are bonded to one another.
[0028] Where a laminated structure incorporating continuous aligned
fibers is employed, the individual layers of composite material can
be positioned relative to one another so that the fibers of one
layer are oriented at an angle relative to the fibers of adjacent
layers. The number of layers of composite material and the fiber
angles are all dependant upon the configuration of the structural
tie and the desired mechanical properties. For example, it may be
necessary for a structural tie to have strength and rigidity with
respect to forces applied in one direction and flexibility with
respect to forces applied in another direction.
[0029] The present invention also contemplates the use of more than
one type of fiber in the same structural tie. For example, two or
more fiber materials can be employed. Where the composite material
is a laminate, the different types of fiber can be present in
individual layers, or different layers can employ different fibers.
The phrase "more than one type of fiber" is also to be construed
herein to mean that the fiber configuration can be different. For
example, chopped and continuous fibers may be used in the same
composite material. Moreover, randomly oriented and aligned fibers
may be used in the same composite material.
[0030] As shown in FIG. 4, the composite material of the present
invention can also include laminated materials having different
polymeric matrices for different layers 20 and 22. The reinforcing
material, as described above, can be the same from layer to layer,
or different. The layers of composite material 20 and 22 each
employ a different thermoplastic or thermosetting material as the
polymeric matrix. In addition, one of the layers of composite
material 20 and 22 can employ a thermoplastic polymeric matrix
material while the other of the layers 20 and 22 employs a
thermosetting polymer as the matrix material.
[0031] Referring to FIGS. 2 and 3, in an embodiment of the present
invention, the structural tie 10 can be bonded to a structural
member 24 by heating a surface of the structural tie to a point
where polymeric material on that surface softens to the point where
an adhesive bond can be made between the structural tie and the
structural member. Where a thermoplastic polymeric matrix is
employed, the matrix material may be used to form the adhesive
bond. Where a thermosetting polymer is employed to form the
polymeric matrix, a layer of heat-meltable polymer that can
function as an adhesive between the structural tie and the
structural member 24 can be coated onto the thermosetting polymer
matrix material. This layer of heat-meltable polymer can be applied
at the time the structural tie 10 is made, or subsequent to
manufacture but prior to use.
[0032] Where a combination of thermoplastic and thermosetting
polymers are employed as the matrix materials in the structural tie
10, depending on what surface of the structural tie 10 will be
heat-bonded to the structural member 24, a layer of heat-meltable
polymer can be applied to the structural tie. If an exposed surface
of the thermoplastic matrix material coincides with the surface of
the structural member 24 to be heat bonded to the structural tie,
the thermoplastic matrix material can be used to operate as the
adhesive material. While the heat bondable material has been
described as a thermoplastic, the present is not limited in this
regard. A thermoplastic elastomer, or an elastomeric material can
also be applied to the structural tie 10 for use in heat-bonding
the structural tie to the structural member 24.
[0033] Turning to FIGS. 5-7, the structural tie 10 can also include
a layer of metallic material to enhance the mechanical properties
of the structural tie. The metallic material can be made from any
suitable material, such as, but not limited to steel, stainless
steel, aluminum, copper, nickel, alloys and metal matrix
composites. As shown in FIG. 5, the layer of metallic material 26
can be positioned adjacent the composite material 28 on the
structural tie 10 so that an outwardly facing surface of the
metallic layer 26 is exposed. Where the portions of the metallic
layer 26 are exposed to the environment in which the structural tie
10 is used, the exposed surface, or the entire metallic layer can
be coated with a polymeric material to prevent degradation of the
metallic layer due to environmental exposure. In the embodiments
shown in FIGS. 6 and 7, the layers of composite material 28 can be
laminated as described above. In addition, the layers of composite
material 28 can be different from one another as described
above.
[0034] Referring to FIG. 6, the layer of metallic material 26 can
be sandwiched between and encapsulated by layers of composite
material 28. In addition, and as shown in FIG. 7, the structural
tie 10 can also have multiple layers of composite material 28 with
the layer of metallic material 26 located on an outer surface of
the structural tie. The layer of metallic material 26 can be coated
with a layer of polymeric material (not shown) to prevent
degradation due to exposure to the environment.
[0035] Although this invention has been shown and described with
respect to the detailed embodiments thereof, it will be understood
by those of skill in the art that various changes may be made and
equivalents may be substituted for elements and steps thereof
without departing from the scope of the invention. In addition,
modifications may be made to adapt a particular situation to the
teachings of the invention without departing from the essential
scope thereof. Therefore, it is intended that the invention not be
limited to the particular embodiments disclosed in the above
detailed description, but that the invention will include all
embodiments falling within the scope of the above description.
* * * * *