U.S. patent application number 14/738851 was filed with the patent office on 2015-12-31 for stiffened frame supported panel.
The applicant listed for this patent is Kenneth Robert Kreizinger. Invention is credited to Kenneth Robert Kreizinger.
Application Number | 20150376898 14/738851 |
Document ID | / |
Family ID | 54929929 |
Filed Date | 2015-12-31 |
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United States Patent
Application |
20150376898 |
Kind Code |
A1 |
Kreizinger; Kenneth Robert |
December 31, 2015 |
Stiffened Frame Supported Panel
Abstract
Frame supported panels with an increased load carrying capacity
derived from inducing newly discovered conditions on panels made
from weaker, lighter and thinner materials. The
fixed/continuous/dropped condition can increase a panel's load
capacity many times based on the panel's interaction with frame
members. This enables foam panels, for example, to be used in
structural applications. It also enables polyurethane foam with any
cladding to provide a comprehensive, structural building panel that
provides a finished exterior, continuous and cavity insulation, an
air, moisture and vapor barrier and increased uplift resistance
while eliminating condensation and thermal
expansion/contraction.
Inventors: |
Kreizinger; Kenneth Robert;
(Fort Lauderdale, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kreizinger; Kenneth Robert |
Fort Lauderdale |
FL |
US |
|
|
Family ID: |
54929929 |
Appl. No.: |
14/738851 |
Filed: |
June 13, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62018551 |
Jun 28, 2014 |
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62033420 |
Aug 5, 2014 |
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Current U.S.
Class: |
52/483.1 |
Current CPC
Class: |
E04B 2/7448 20130101;
E04C 2002/3488 20130101; E04C 2/284 20130101 |
International
Class: |
E04B 2/72 20060101
E04B002/72; E04F 13/24 20060101 E04F013/24 |
Claims
1. A frame supported panel with an increased load capacity
comprised of: a. a single or a multitude of frame members having a
top edge, a bottom edge and two sides and said frame members are
spaced a distance apart with one or more spans between said frame
members and b. a panel with a continuous section and one or more
dropped sections to comprise one or more thickened sections and c.
said continuous section supported by said frame members and
continuous over said top edges and said continuous section has a
thickness of 0.02'' to 6'' and has a continuous conditioned load
capacity over each said span and d. said dropped sections situated
between said sides and e. said thickened sections have a flexural
stiffness and f. said panel fixed to said top edges and/or to one
or more said sides with a bonding technique and said bonding
technique has a bonding capacity of at least 10 psi and g. said
panel has a fixed/continuous/dropped condition with an increased
load capacity, over at least half of said spans, that is at least
25% greater than said continuous conditioned load capacity and h.
said frame members have sufficient rotational resistance to
facilitate at least said 25% greater load capacity, i. whereby said
panel has an increased load capacity.
2. A frame supported panel of claim 1 wherein said increased load
capacity is predetermined.
3. A frame supported panel of claim 1 wherein said increased load
capacity is at least 50% greater than said continuous conditioned
load capacity and said increased load capacity is
predetermined.
4. A frame supported panel of claim 1 wherein said increased load
capacity is at least 100% greater than said continuous conditioned
load capacity.
5. A frame supported panel of claim 1 wherein said dropped sections
comprise fillets and said fillets are fixed to said frame members
and are optionally bonded to said panel and said increased load
capacity is at least 100% greater than said continuous conditioned
load capacity and said increased load capacity is
predetermined.
6. A frame supported panel of claim 1 wherein said panel is a foam
backed panel comprising a continuous/dropped configuration with
slots for the insertion of said frame members.
7. A frame supported panel of claim 1 wherein said panel is a foam
composite panel comprised of a cladding with foam adhesively bonded
to at least part of said cladding's backside and said foam has a
modulus of elasticity of at least 100 psi and provides at least 5%
of said flexural stiffness over at least half of said spans.
8. A frame supported panel of claim 7 wherein said increased load
capacity is at least 100% greater than said continuous conditioned
load capacity and said increased load capacity is
predetermined.
9. A frame supported panel of claim 7 wherein said dropped section
comprise fillets and said fillets are fixed to said frame members
and said fillets are optionally bonded to said panel and said
increased load capacity is at least 100% greater and said increased
load capacity is predetermined.
10. A frame supported panel of claim 7 wherein said panel is a
frame supported ribbed panel.
11. A frame supported panel of claim 7 wherein said panel is a
ribbed structural section.
12. A frame supported panel of claim 7 wherein a mesh is continuous
over and bonded to said frame members and embedded in said foam as
an anti-penetration layer.
13. A frame supported panel of claim 7 wherein cladding spacers
situated between said cladding and said frame members provide a
spacing and said foam occupies at least part of said spacing.
14. A frame supported panel of claim 7 wherein said panel is a foam
core slotted sandwich panel having an outside as said continuous
section and a slotted inside as said dropped section.
15. A frame supported panel of claim 7 wherein said panel is
manufactured and fixed to said frame members with a spray-up
process.
16. A frame supported panel of claim 7 wherein said foam provides
at least 20% of said flexural stiffness.
17. A frame supported panel of claim 7 wherein two or more said
panels are spliced together by polyurethane foam to form a single
panel with structural continuity.
18. A frame supported panel of claim 7 wherein said foam is a
polyurethane foam and said foam is thickened at a later time with
additional polyurethane foam whereby said foam has structural
continuity thickness.
19. A frame supported panel of claim 7 wherein an enhanced
continuous condition is induced on said panel and said panel has 2
or more inside spans and an increased load capacity of outside
spans to correspond to the load capacity of said inside spans.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the filing date of
U.S. Provisional Application Nos. 62/018,551 filed Jun. 28, 2014
and 62/033,420 filed Aug. 5, 2014, both incorporated herein by
reference.
INVENTION BACKGROUND
[0002] The inventive subject matter comprises is a frame supported
panel utilizing four new conditions that enable weaker, lighter and
thinner panels to be made stiffer and more versatile by
re-configuring the panel's shape and/or by sufficiently bonding the
panel to frame members. These conditions substantially increase the
stiffness and load strength of these panels by many times for a
dramatic increase in load carrying capacity.
[0003] There has been a long felt need to increase a panel's load
capacity at little or no cost and especially that of foam or foam
composite panels used as building panels for walls and roofs. Since
many weaker, lighter and thinner panels have desirable properties
there is a need to make them structural in order to consolidate
these desirable properties into a structural product. This is
especially true for polyurethane foam panels which can provide an
air, vapor, moisture and thermal barrier, eliminate condensation,
decrease thermal contraction and expansion and increase uplift
resistance. As such, making polyurethane foam structural would
provide a most comprehensive building panel.
[0004] Increasing load capacity of panels has typically been
accomplished by changing the panel's design with stronger or
thicker materials, by using stronger material shapes or by
shortening the span between frame members, all of which have
limitations and/or increase the panel's costs. In addition, it is
well known that a beam or panel in a continuous condition over two
or more same sized spans can carry more than a 100% increase in
load capacity as compared to the same panel over a single, same
sized span.
[0005] A continuous condition occurs when a beam or panel is
continuous over two or more spans created by spaced apart supports
or frame members. In this case the increased load capacity is
caused by a reaction from a portion of a panel over one span to a
sufficiently large force or load applied to the same panel over an
adjacent span. As a load is applied to one span, the panel over the
adjacent span(s) resists the load causing the panel to have an
increased load capacity. As a result, plywood, form boards and
walers all have an increased load capacity when they are continuous
over two or more same sized spans. The continuous condition has
only been applied to panels that are entirely above the frame
members. In other words the entire continuous configured panel is
above the plane created by the top edge of adjacent frame members
bearing the panel. As such, it is unknown how the load capacity of
a continuous panel is affected if a portion of the panel is
thickened and dropped below this plane.
[0006] It is well know that the continuous condition has inside and
outside spans and the insides spans have an inherently higher load
capacity than the outside spans. This increased load capacity is
presently wasted since most panels have only one or two inside
spans and the panel's load capacity is determined by it's weakest
span, which is the outside span. This is an unrecognized problem
and a need exists to utilize this wasted load capacity.
[0007] The continuous condition is derived from fundamental beam
theory which is over 100 years old. This theory also teaches that a
beam subjected to a fixed boundary condition can have a its load
capacity increased up to 400%. A fixed boundary condition exists
when the ends of a beam over a single span are fixed as opposed to
being simply supported. In order to adequately fix the ends of a
beam to prevent it from rotating, the entire perimeter of each end
must be fixed to the frame members which only occurs if the beam is
fixed to the frame member's sides, as opposed to their top. Fully
fixed ends prevents beam rotation to enable the beam to use its
full potential strength.
[0008] While fundamental beam theory's fixed boundary condition
suggests that a material used as a beam can have its load capacity
increased by 400%, the theory is silent as to its practical
application, techniques and the materials to which it is
applicable. Since beams are structural components, the materials
typically considered for use as beams are also structural such as
steel, other metals, wood and reinforced concrete. Given that such
materials are rigid and have a high modulus of elasticity, it has
not been known whether the fixed boundary condition can be applied
to pliable, soft or otherwise weaker materials such as foams.
[0009] Despite the fact that mathematical exercises predicting an
increased load capacity from a theoretical fixed boundary condition
are widely known, there are few techniques by which to apply the
theory and these are limited to steel, other metals and reinforced
concrete. Beyond these materials there are no known techniques for
attaining a 400% increase in load capacity in most other materials.
As a result the practical application of the fixed boundary
condition theory is unknown on most materials.
[0010] Of the two conditions, the continuous condition is widely
practiced whereas the fixed boundary condition remains mostly
theory. The continuous condition is the most common connection of a
panel to any type of solid or framed structure. It is extensively
used to attach sheathings, claddings, decks, coverings, etc. for
buildings, furniture and other applications and for a variety of
reasons. One important reason the continuous condition is so widely
used is that it provides a continuous planar surface over frame
members. On the other hand, a fixed boundary condition does not
provide a continuous planar surface since its entire end perimeter
theoretically needs to be fixed to the side of frame members. As
such, the sole appeal of the fixed boundary condition is its
theoretical increase in load capacity, which has been of little
value since increasing load capacity is easily accomplished by
increasing the thickness of a continuous conditioned panel. For
example 5/8 inch thick plywood has about twice the load capacity as
1/2 inch plywood over the same span. Therefore, with such an easy
and inexpensive solution to increasing a panel's load capacity
there is no motivation to make the fixed boundary condition
useful.
[0011] It is well known that a fixed boundary condition can be
induced on steel beams by either welding or with steel bolts. This
is not the case with fasteners and adhesives used to fix non-metal
materials to a frame. Prior art demonstrates that some increase in
load capacity has been attained using fasteners and adhesives to
fix wood to a frame, although nowhere near the 400% theoretical
increase possible with a fixed boundary condition. Since the
success with attaining an increase in load capacity by fixing wood
to a frame is severely limited as compared to fixing steel, the
likelihood of attaining an increase in load capacity by fixing a
much weaker material such as a foam to a frame was unexpected.
[0012] Composite action has been widely applied to wall, floor or
roof assemblies, where increased load capacity or greater
structural integrity of the frame members, assembly or diaphragm
has been recognized by adequately bonding a sheathing to the frame
members. It is also well known that polyurethane foam can be used
to bond sheathing or claddings to frame members and thereby reduce
racking and increase the structural integrity of an entire
structural wall or roof section. However, no disclosure shows
whether or not such bonding can increase the load capacity of the
sheathing itself between frame members.
[0013] It is well known that structural building panels, such as
plywood sheathing, require a minimum load capacity and therefore
determining load capacity is fundamental to the building panel's
design. For 50 years polyurethane foam has been adhesively bonded
to more rigid materials and used as building panels that required
the determination of the panel's load capacity in order to meet
building codes and be permitted for use. In many of these cases the
polyurethane foam was also adhesively bonded to frame members.
However, in no case has it been recognized that bonding
polyurethane foam to both the rigid material panels and to the
frame members results in an increased load capacity to the
polyurethane foam/rigid material composite panel. Nor has it been
disclosed that polyurethane foam itself has an increased load
capacity induced solely by its bond to frame members.
[0014] Moreover, polyurethane foam has been used extensively
throughout the world as thermal insulation installed by bonding it
to sheathing, creating a composite panel, and simultaneously
bonding that composite panel to studs or trusses. Yet it has been
unrecognized that this same procedure produces a continuous
composite panel having a dropped section (polyurethane foam)
between the studs or trusses that is bonded to frame members in a
possible fixed boundary condition. Despite literally thousands of
people, who have researched, designed, marketed, applied or
otherwise worked with polyurethane foam in this way, no one has
recognized that polyurethane foam itself or as part of a composite
panel bonded to frame members can increase the panel's load
capacity. Instead, the prior art is either silent about a panel's
load capacity or teaches increased load capacity of the entire
frame diaphragm rather than of the panels themselves. For
example:
[0015] U.S. Pat. No. 3,258,889 (Richard A. Butcher) discloses a
structural wall comprised of polyurethane foam bonded to the back
of an interior wallboard and to the sides of studs and teaches
added stiffness of the framed wall that enables the use of thinner
panels and lighter frame members. U.S. Pat. No. 3,641,724 (James
Palmer) discloses a wall section comprised of an exterior cover
bonded to the sides of stud members by a polyurethane foam that
increases the strength of the entire structure. U.S. Pat. No.
4,471,591 (Walter E. Jamison) discloses a wall assembly with an
exterior section comprised of polyurethane foam bonded to sheathing
and to the sides of studs. U.S. Pat. No. 4,748,781 & 4,914,883
(Stanley E. Wencley) discloses polyurethane fillets bonding a panel
to frame members to provide an increased strength bonded
structure.
[0016] U.S. Pat. No. 5,736,221 (James S. Hardigg, et al) discloses
two half panels with each having a face and a web molded to the
face's backside and the webs bonded together to provide a panel
having bending strength in all directions. U.S. Pat. No. 8,397,465
(Jeffrey M. Hansbro et al) discloses a wall assembly comprised of
polyurethane foam panels bonded to the sides of structural members
(studs) and to foam boards continuous over the structural member's
edge. U.S. Pat. No. 8,696,966 (Jason Smith) discloses a method of
fabricating a wall structure whereby polyurethane foam is applied
against a form and the foam expands to become a panel bonded to the
edges and sides of support members (studs) within a wall frame.
WO/2013/052997 (John Damien Digney) discloses a composite panel
system reinforced with wire mesh and comprised of a structural
cladding spaced apart from and bonded to a studded frame with
polyurethane foam that is between and continuous over the
studs.
[0017] US 2014/0053486 (Anthony Grisolia et al) discloses a wall
structure including support members inside the frame (studs) and a
polyurethane foam panel both continuous over and between the
support members. US 2014/0115988, US 2014/0115989 and US
2014/0115991 (Michael J. Sievers, et al) discloses a wall assembly
of a frame assembly with vertical members (studs) and an insulating
foam layer disposed between and on top of the vertical members. US
2014/0174011 (Jason Smith) discloses a method of fabricating a wall
structure comprised of bonding polyurethane foam to the edge and
sides of frame members. US 2015/0093535 (James Lambach et al)
discloses a framed panel with a polyiso board continuous over frame
members and bonded to the sides of frame members with polyurethane
foam.
[0018] None of the above or other prior art disclose that a
continuous conditioned foam or foam composite panel has an
increased load carry capacity solely due to a bond with frame
members. Nor does the prior art disclose that there is sufficient
rotational resistance in place to enable the panels to carry a
larger load. Nor does the prior art disclose that a dropped section
between frame members can increase the load capacity of a
continuous conditioned panel. Nor are fillets, used as dropped
sections, known for their ability to shorten a span so as to
increase a panels' load capacity. Nor has it been disclosed that
polyurethane foam can be used to create large, continuous panels
over many spans to take advantage of the inside span's inherent
increased load capacity.
[0019] Despite bonding foam or foam composite panels to frame
members and panels with a continuous/dropped configuration used
extensively for decades as building panels that required the
determination of the panel's load capacity, none of the new
conditions of the inventive subject matter have been previously
disclosed as a bases for increasing a panel's load capacity. As
such, it has not been obvious by a person of ordinary skill in the
art to combine a panel's continuous condition with a fixed boundary
condition to increase the panels load capacity. Nor has it been
obvious to add a dropped section to a continuous conditioned panel
to increase the panel's load capacity. Nor has it been obvious that
rotational resistance is necessary to facilitate increases in load
capacity.
[0020] The problems to be solved by this inventive subject matter
are first: to increase the load carrying capacity of panels
comprised of weaker, lighter and thinner materials, and second: to
utilize the presently unrecognized increased load capacities of a
panel's inside spans.
SUMMARY OF INVENTION
[0021] The inventive subject matter is the application of four new
conditions on weaker, lighter, thinner and less costly panels to
enable them to become stiffer, stronger and more versatile by
re-configuring the panel's shape and/or by sufficiently bonding the
panel to frame members. The effectiveness of these new conditions
is inversely related to a panel's flexural stiffness in that the
smaller the flexural stiffness the greater the effect the
conditions have in increasing a panel's load capacity. Panels with
the lowest flexural stiffness can have thousands of times increases
in load capacities. As a result, non-structural materials, such as
foam insulation, may be converted into structural applications to
facilitate a new generation of multi-functional structural
panels.
[0022] Due to the lack of literature on the application of fixed
boundary conditions to beams or panels made of materials much
weaker than steel or concrete, testing was initiated to study the
effects of a fixed boundary and continuous condition on the load
carrying capacity of foam panels and thin wood panels supported by
a frame. The object was to determine whether these boundary
conditions are applicable to such materials and if so, to what
extent they affect the various material's load carrying capacity
when used as panels. Several configurations were tested leading to
the discovery of the four new conditions and their dramatic impact
on increasing a panel's load capacity.
[0023] While the continuous condition is well known, combining it
with the fixed boundary condition is only known for a limited
number of materials, all of which have a high modulus of
elasticity. Specifically, continuous panels made of steel (metals),
reinforced concrete and wood have all been sufficiently fixed to
frame members such that some degree of increased load capacity was
attained from the combination of the continuous and fixed boundary
conditions. However, no prior art combines the continuous condition
with the fixed boundary condition on low modulus of elasticity
materials such as foam or foam composite panels. In addition,
despite substantial prior art showing a polyurethane foam composite
panel in a continuous condition and bonded to frame members, either
the configuration didn't induce a fixed boundary condition or if it
did, it was unrecognized. Finally, the techniques used on steel,
reinforced concrete and wood to attain a fixed boundary condition
are not transferable to foam.
[0024] The continuous/dropped configuration has been used for such
things as dropped ceiling tiles although it has not been recognized
as a condition that can increase a panel's load capacity. The
continuous/dropped configuration and condition has the top or
outside section of a panel continuous over one or more spaced apart
frame members while the bottom or inside section of the panel is
thickened and dropped between the sides of frame members. This is
distinguished from a continuous panel which is completely above the
frame members or more precisely above a plane or a perimeter
created by the frame member's top edges that are supporting the
panel. A continuous/dropped panel may or may not be bonded to frame
members. If it is sufficiently bonded to frame members to induce a
fixed boundary condition, it becomes a fixed/continuous/dropped
condition, another new condition of this inventive matter.
[0025] The continuous/dropped configuration is the reverse of known
dropped panels configurations used to increase the panel's load
capacity. For example, to strengthen concrete floor panels a
dropped or thickened section is added over the columns or beams,
such as a capital, and a thinner section is over the spanned area.
While the continuous/dropped panel configuration has been shown in
numerous prior art disclosures, such as polyurethane foam bonded to
the inside of sheathing, it's ability to increase the panel's load
capacity has gone unrecognized for at least 50 years.
[0026] As used in this disclosure the term load capacity, also
known as load carrying capacity, is a panel's maximum load it can
carry, or force it can withstand, over a given span before the
panel deflects more than a given amount. As the amount of load
increases on the panel over the span the panel reacts by rotating
which causes deflection. Due to the problems caused by excessive
deflection, load capacity is an important element of almost all
frame supported panels, regardless of application. In many
applications there is a maximum, allowable amount of deflection for
a given load. For example wall panels may be required to carry a
minimum lateral load of 40 psf (pounds per square foot) without
deflecting more than L/240. For example, if span length "L" is 16
inches, the panel cannot deflect more than 16/240 or 0.067 inch
when the given 40 psf load is applied. A span is the distance
between spaced apart frame members and therefore is both a length
and a space. The term "one or more spans" refers to either a
single, undivided space between frame members or to a multitude of
spaces separated from each other by multiple spaced apart frame
members.
[0027] A panel's load capacity is determined by its material
composition, shape, length of span and allowable deflection. For
purposes of this disclosure, a panel's material composition and
shape comprise its "flexural stiffness" which is defined as EI
("E", a material's modulus of elasticity, multiplied by "I", the
panel's moment of inertia). Flexural stiffness refers to a panel's
material and the shape of its cross section and is stated in psi
(pounds per square inch).
[0028] Formulas have been developed to predict deflection for a
given load over a given span for beams with a simply supported
condition, a continuous condition and a fixed boundary condition.
These formulas have been found applicable to panels where the span
is determined by two spaced apart frame members, similar to beam
support members. The formulas provide a way to mathematically
compare a panel's predicted load capacity under different
conditions.
[0029] A simply supported panel is over a single span with opposite
ends of the panel supported by spaced apart frame members without
any sufficient means for the panel to resist rotation. The panel
may be unbonded or bonded to the frame members, although any such
bond, such as nails, is insufficient to induce a fixed boundary
condition on the panel and thereby the panel is unfixed. The
maximum deflection formula for a simply supported condition is
d=5wL.sup.3/384EI where "d" is the amount of deflection in inches,
"w" the uniformly distributed load, "L" the span length in inches,
"E" the material's modulus of elasticity and "I" the panel's moment
of inertia. This formula provides the basis for determining a
simply supported panel's load capacity per inch of panel width as:
w=76.8dEI/L.sup.3 for a uniformly loaded panel.
[0030] A simply supported panel's load capacity can be increased by
subjecting the panel to conditions that enable the panel to stiffen
and thereby increase its load carrying capacity to support greater
loads for a given deflection. One well known condition is a
continuous condition whereby a panel is continuous over the top and
bears on the top of three or more spaced apart supports, i.e. frame
members, and is thereby continuous over two or more spans. The
continuous condition increases a panel's load capacity by a
reaction from the part of a panel over one span to a force or load
applied to the same panel over an adjacent span. As a load is
applied to one span, the panel over the adjacent span(s) resists
the load causing the panel to have an increased load carrying
capacity. A panel that is continuous over and supported by spaced
apart frame members that create two or more spans, is a continuous
panel in a continuous condition and has an increased, continuous
conditioned load capacity, over each span, that is greater than the
panel's simply supported load capacity. Such a panel may be
unbonded or bonded to the frame members although any such bond is
insufficient to induce a fixed boundary condition on the panel and
thereby the panel is unfixed. To support a panel means the panel
bears on or is held up by supports, a frame or frame members and to
support a load means to carry or bear a load.
[0031] For clarification purposes, an increased load capacity or an
increase in load capacity is a load capacity that has been
increased from some previous amount of load capacity and results in
a greater load capacity. For example a continuous conditioned panel
has an increased load capacity above that of itself in a simply
supported condition and thereby has a new, greater load capacity.
Also, when a continuous panel over several spans is herein compared
to a simply supported panel, the continuous panel's length is
assumed to be shorted to that of the simply supported panel over a
single span, while the panel's flexural stiffness, span length and
load remain the same.
[0032] The maximum deflection formula for a continuous conditioned
panel over two equal spans with uniformly distributed loads is:
d=wL.sup.3/185EI and therefore the panel's continued conditioned
load capacity per inch of panel width can be determined by the
formula: w=185dEI/L.sup.3. Comparing this to the simply supported
formula shows that a continuous condition induces an increase in
load capacity of about 141% above that of a simply supported panel
((185-76.8)/76.8). As such, a panel continuous over two spans has a
load carrying capacity increase of 141% over the same shortened
panel has over the same single span. This 141% increased capacity
can be used to compare the increased load capacity of a continuous
conditioned panel over a span to the panel's simply supported load
capacity. The amount of increased capacity and formula may vary
depending upon the circumstances such as unequal spans, different
loads, additional support, etc. In those cases where a formula is
non-existent, load testing can be used to determine the load
capacity. Unless otherwise herein noted, loads are uniformly
distributed loads and two or more spans shall be assumed to be
equal spans and all load tests were conducted with the maximum
deflection of L/240.
[0033] Another continuous condition occurs when a panel is
continuous over three or more spans and the two outer spans have
greater deflection than the spans in a two span condition. This
occurs because the center or inside span is reacting to loads on
outside spans on both sides which causes it's reaction to be split
between two adjacent spans and thereby less effective than if
reacting to a single span in a two span condition. On the other
hand, since the inside span is supported by spans on both sides, it
has a much higher load carrying capacity. As such, a panel
continuous over three equal spans has a continuous condition
increase of only 89% on the outside spans and a much higher
increase of about 285% on the inside span over a simply supported
panel. A panel continuous over four or more equal spans has a 100%
increase in load capacity for its outside spans and about a 212%
increase in load capacity for its inside spans. A panel continuous
over five or more equal spans has a 90% increase in load capacity
for its outside spans and about a 230% increase in load capacity
for its inside spans over a simply supported panel. These increases
are derived from well known formulas that determine the maximum
deflection on continuous panels with uniformly distributed loads
over equal spans.
[0034] The third beam theory condition is a fixed boundary
condition where a panel is over a single span with two opposite
ends fixed to the sides of the supporting frame members to prevent
the panel from rotating. A fixed boundary beam is always depicted
as being fixed to the sides of frame members, suggesting that
fixing the entire end perimeter is required to prevent rotation. A
fixed boundary panel has five times the load capacity of the same
simply supported panel which is a 400% increase. The maximum
deflection formula for a fixed boundary conditioned panel is:
d=wL.sup.3/384EI and the formula for the load capacity per inch of
panel width is: w=384dEI/L.sup.3.
[0035] While a fixed boundary condition theoretically has a 400%
increase in load capacity over a simply supported panel, it is a
misnomer in that testing showed that the increase is really a
variable from ranging from a 1% to 400%, depending upon the
sufficiency of the panel to frame member bond. Therefore, for
purposes of this disclosure, a fixed boundary condition is
recognized as having some increase in load capacity up to 400%
while a fully fixed boundary condition is one that has attained the
full 400% increase in load capacity.
[0036] In order to compare the effectiveness of the new conditions,
it is necessary to compare their load carrying capacities with
those of known conditions and specifically to the simply supported
and the continuous conditioned panel. Where applicable, the above
continuous conditioned percentage increases can be used to
determine the continuous conditioned load capacity from a known
simply supported load capacity. Or, load testing can be used on
different continuous conditioned panels with a variety of different
configurations of frame members, loads, spans, etc. Once a panel's
simply supported and/or continuous conditioned load capacity is
determined, it can be compared to any increased load capacity
induced on the same panel by the new conditions. The load capacity
induced on a panel by the various new conditions will have to be
determined by load tests until such time formulas may be developed
that consider all of the variables.
[0037] While the techniques for applying both the simply supported
and continuous condition to a panel of any material are obvious,
"fixing" a panel is much more ambiguous, especially when applied to
different materials and the historic inference that the entire
perimeter of each panel end must be fixed to the side of frame
members. Fixing a panel or a fixed panel is where a sufficient bond
exists between the panel and frame members to induce a fixed
boundary condition on the panel. The object of fixing a panel is to
prevent the panel from rotating. Given that different materials
have different properties it is obvious that techniques to prevent
rotating differ from material to material. For example, the
techniques used to fix a steel or a concrete panel are very
different from those used to fix a foam panel.
[0038] As such, both the simply supported and the continuous
conditions are easy to apply and widely used. The fixed boundary
condition, on the other hand, is little used outside of structural
steel frames, reinforce concrete, reinforced resins and to some
degree wood applications. Structural steel connections can be fixed
by welding or multiple bolts to prevent rotation while reinforced
concrete and reinforced resin connections are inherently fixed.
Wood has had limited success in that only small increases in load
capacity have been disclosed to date.
[0039] Beyond this there is a lack of prior art concerning the
practical application of the fixed boundary condition to other
materials, especially materials having a low modulus of elasticity
or panels having a low flexural stiffness. In addition, given that
steel, reinforced concrete and reinforced resin all have a higher
modulus of elasticity than wood, and wood has had much less success
in attaining a fixed boundary condition, this suggests that the
fixed boundary condition's application may decrease with a
material's modulus of elasticity. As such, it appears the fixed
boundary condition is fully applicable to steel and reinforced
concrete and only partially applicable to wood and by extension
inapplicable to foam. For these reasons the ability to increase the
load capacity of a foam with a fixed boundary condition was
unexpected. Substantial testing was undertaken as part of this
disclosure and unless otherwise noted all testing herein referred
to was done for this disclosure. Testing revealed that a fixed
boundary condition is not only applicable to weak, light and thin
materials but is easily attained through certain material
appropriate techniques. Through testing it was found that a fixed
boundary condition was actually easier to induce on materials
having a low modulus of elasticity or panels having a low flexural
stiffness than on panels with much higher flexural stiffness. In
fact, techniques were developed that enable far more than a 400%
increase in load capacity on weaker material panels so that a
material such as foam can be transformed into a multi-functional
structural panel with a load capacity greater than plywood. Testing
also found that a fixed boundary condition may be obtained by
sufficiently bonding a panel to the frame member's sides and/or top
edges and that it also applies to continuous panels.
[0040] Several findings were made including that an adhesive bond
alone or in conjunction with fasteners does not necessarily produce
an increase in a panel's load capacity. Rather, in order to attain
any degree of a fixed boundary condition on a panel, a sufficiently
high bonding strength must be present on each of at least two
spaced apart frame members creating the span and the sufficiency of
the bonding strength is dependent upon the panel's flexural
stiffness. The higher the panel's flexural stiffness the higher the
required bonding strength to induce a fixed boundary condition.
Moreover, the required bonding strength was also found to be a
multiple of the load supported over a span and the greater the span
the greater the multiple. Therefore, as a panel's load capacity
decreases, the bonding strength must be increased. As a result of
these and other findings, techniques were developed to obtain
sufficiently high bonding strengths.
[0041] As used herein, a bond or bonding is something that binds,
fastens, confines, or holds together and may also refer to using an
adhesive, cementing material, or fusible ingredient that combines,
unites, or strengthens and also to a bonding technique such as
thermal bonding. Adhesive refers to both a substance and/or
technique that causes something to adhere to a material or that is
designed to adhere to produce an adhesive bond. Bonding strength is
herein defined as the amount or degree of bond between a panel and
frame members and is measured in pounds per square inch (psi).
[0042] Once testing provided a better understanding of a fixed
boundary condition and possible techniques, four new conditions
were developed to make the fixed boundary and the continuous
conditions more effective and applicable to other materials. Each
of these four new conditions provide a panel with an increased load
capacity. The first new condition is called the fixed/continuous
condition and it combines the fixed boundary and the continuous
conditions. The second new condition is the continuous/dropped
condition which increases the load capacity of panels by adding a
dropped section to the panel over the span. The third new condition
is the fixed/continuous/dropped condition and it combines the fixed
boundary and the continuous/dropped conditions. These new
conditions enable weaker, lighter and thinner panels to easily
attain as much as a 1,000,000% or more increase in load capacity
and thereby may be substituted for panel materials having a much
higher modulus of elasticity. The fourth new condition is the
enhanced continuous condition which capitalizes on the much higher
load capacities of the inside spans.
[0043] The first new condition, the fixed/continuous condition,
combines the fixed boundary and the continuous conditions and is
most effective on low modulus of elasticity materials such as foam.
The fixed/continuous condition is a panel supported by spaced apart
frame members with a continuous section that is continuous over and
fixed to the top edges of the frame members. Unlike the fixed
boundary or the continuous conditions, the fixed/continuous
condition may be induced on a panel over a single or multiple
spans. The fixed/continuous panel is sufficiently bonded to the
frame member's top to induce a fixed boundary condition and is
continuous over at least part of the supporting frame members.
Although the panel is bonded to the frame member's top as opposed
to it's side, which will limit the degree of fixed boundary
condition attained, combining the conditions can more than
compensate for such reduction since more than a 400% increase in
load capacity is possible. As a result, a fixed/continuous
conditioned panel has a substantial increase in load capacity over
that of a continuous panel.
[0044] The second new condition, the continuous/dropped condition,
occurs when a panel has a continuous section and a dropped section
which combine to form a thickened section. The continuous/dropped
condition is a panel supported by spaced apart frame members with a
continuous section that is continuous over the frame member's top
edges and a dropped section that is between the frame member's
sides and in contact with the continuous section. The panel is not
fixed to the frame members. The continuous section is that part of
the panel that is continuous over frame members and over spans
created by spaced apart frame members supporting the panel and
thereby the panel has a continuous condition. All continuous panels
have a continuous section. The dropped section is that part of the
panel below, behind or otherwise adjacent to the continuous section
and is between the sides of frame members and thereby below or
behind the plane created by the frame member's top edges. It is the
dropped section and its relationship with the frame members that
provide the increased load capacity above that provided by a
continuous condition. While the continuous condition relies solely
upon the rotational resistance provided by a portion of the panel
over an adjacent span for its increase in load capacity, the
continuous/dropped panel relies upon a thickened panel section over
the span and, where it exists, the rotational resistance from an
adjacent span. The continuous/dropped condition may be applied to
both a simply supported panel and a continuous conditioned panel by
adding a dropped section and therefore the simply supported panel
and the continuous conditioned panel may be called continuous
sections.
[0045] Sufficiently bonding a continuous/dropped panel to frame
members induces a fixed boundary condition on the panel that
further increases a panel's load capacity. This combination is
called a fixed/continuous/dropped condition and may be induced on a
panel over a single or multiple spans. The fixed/continuous/dropped
condition is a panel supported by spaced apart frame members with a
continuous section that is continuous over the top edges of the
frame members and a dropped section situated between the frame
member's sides and in contact with the inside of the continuous
section. The panel is fixed to the top edges and/or the sides of
the frame members. The dropped section may be situated in any
number of spans in a continuous dropped or a
fixed/continuous/dropped condition. The term one or more dropped
sections shall mean that either a single dropped section may be
situated in any number of the spans or more than one dropped
sections, such as two fillets, may be situated in any number of the
spans. A major advantage of both the continuous/dropped condition
and the fixed/continuous/dropped condition is that a panel's load
capacity can be increased without increasing the structural
section's thickness. Of all the new conditions, the
fixed/continuous/dropped condition can provide the greatest
increase in load capacity by 1,000,000% or more in some situations.
This is due in part to the additional bonding area made available
by the dropped section's interface with the frame members, which
can substantially increase the degree of fixed boundary condition
induced on the panel. It was also discovered that fillets can be
used as dropped sections to both further increase the bonding area
and to effectively shorten the span which greatly affects a panel's
load capacity.
[0046] For example, a fixed/continuous/dropped condition induced on
a one inch continuous panel with a load capacity of about 2.9 psf
over a 14.5 inch span can be increased about 500% to 17.4 psf by
adding a one inch dropped section. A partial fixed boundary
condition is also induced causing another two times increase in
load capacity to about 34.8 psf. Finally, fillets can be used to
effectively shorten the span by two inches to 12.5 inches which
increases the load capacity to 64 psf. As a result, the
fixed/continuous/dropped condition increased the panel's continuous
load capacity by 2200% from 2.9 psf to 64 psf.
[0047] The fourth new condition, the enhanced continuous condition,
greatly improves the effective load carrying capacity of a panel by
increasing the load capacity of the outside spans to correspond to
that of the inside spans. Presently a panel's load capacity rating
is determined by its weakest section which is the panel's outside
spans. Due to span reaction, the inside span's load capacity can be
as much as a 220% increase over that of the outside spans, which is
wasted since the weakest spans control. By increasing the load
capacity of the two outside spans to correspond to its inside
spans, the panel has a much higher load carrying capacity rating.
While this may be of little value for traditional panels spanning
three of four spans, it's exceptionally beneficial to panels
created to span six or more spans, since the cost of increasing the
outside span's load capacity is negligible as compared to
increasing the entire panel's load capacity. By using polyurethane
foam as part of a composite panel, it is possible to create a
single panel with numerous inside spans covering an entire wall,
roof or even much of an entire building.
[0048] The structural section disclosed herein is a single faced
structural section comprised of one or more frame members providing
some degree of a frame with one or more panels continuous over the
top or outside of the frame and, where necessary, rotational
resistance members attached to the bottom or inside of the frame
members. As used herein, a frame is comprised of one or more
individual frame members that may or may not be in contact with one
another and that provide a partial or full border for a panel or
structural section. A frame may include individual frame members
internal to the border, such as studs between a top and bottom
plate and/or frame members external to the border such as rafters
extending beyond a top plate. A panel may be cantilevered beyond a
frame member or a frame's border. The terms spaced a distance apart
or spaced apart frame members shall mean that at least part of the
frame member's sides are not in contact with those of an adjacent
frame member, or itself, such that a span, i.e. a distance and a
space exists between the frame members.
[0049] A major finding was that the bonding strength necessary to
induce a fully fixed boundary condition is a function of the
panel's flexural stiffness. The higher the flexural stiffness, the
greater the required bond, meaning that 1/2 inch plywood for
example, will require a bond strength many times greater than that
needed for two inch foam. This explains why fasteners used to
attach wood panels to frame members have little or no impact on
increasing the panel's load capacity. It also exposes the ability
of low flexural stiffness panels to be much more susceptible to a
load capacity increase induced by a fixed boundary condition.
[0050] The testing led to several unexpected results such as a
typical two pound density polyurethane foam has a sufficient
bonding strength to induce a fixed boundary condition on itself or
other foams that increases the foams bonding capacity by many
times. Prior to this it was unrecognized that polyurethane foam
could induce a fixed boundary condition on itself or anything else.
Another unexpected result was that a foamed composite panel
sufficiently bonded to frame members can induce a fixed boundary
condition on the flexural stiffness of the entire composite panel,
not just on the foam.
[0051] Another unexpected result was that material appropriate
fillets can significantly increase a panel's load capacity by
several hundred or thousand percent by increasing the degree of
fixed boundary condition and/or by effectively shortening the
span.
[0052] Another unexpected result was that a dropped section can
increase a continuous panel's load capacity by several hundred
percent.
[0053] Another unexpected result is that increases in load
capacities induced by conditions are in series, with each
subsequent condition a multiple of prior induced conditions such
that a panel's load capacity may be increased thousands of times by
compounding conditions.
[0054] Another unexpected result is that the fixed boundary
condition is applicable to foam and other materials having a low
modulus of elasticity.
[0055] Another unexpected result was that the inducement of a
fixed/continuous condition on a panel can increase the panels load
capacity to more than the combined 540% increase by the fixed
boundary condition (400%) and the continuous condition (140%).
[0056] Another unexpected result was that polyurethane foam can
splice individual panels into a large, single panel with multiple
spans and induce a continuous conditioned structural continuity
over the spans to make all but two inside spans that have an
inherently higher load carrying capacity that was previously wasted
and a previously unknown problem.
[0057] It was also found that the bonding strength required for a
fully fixed boundary condition was a multiple of the load and the
longer the span, the greater the multiple. For example, a panel
over a 14.5 inch span may require a bonding strength of 50 to 90
times the load on that span whereas the same panel over a 24 inch
span may require a bonding strength over 200 times the load. Again,
the higher the material's flexural stiffness and the longer the
span, the greater the required bond strength to induce a fixed
boundary condition. This also shows that increasing bonding
strength can offset a longer span's decrease in load capacity.
[0058] Accordingly, one advantage of the inventive subject matter
is that weaker, thinner, lighter, more versatile and less expensive
materials can be used as structural panels.
[0059] Another advantage is that all types of panels can have an
increased load capacities of of several times and in some cases
several thousand percent increase above the same simply supported
panel.
[0060] Another advantage is that polyurethane foam bonded to a
cladding and frame members can become a comprehensive structural
panel that provides a finished exterior, continuous and cavity
insulation as well as an air, moisture and vapor barrier, increased
uplift resistance and the elimination of condensation and thermal
expansion/contraction.
[0061] Another advantage is that adding fillets can increase a
panel's load capacity by several thousand percent above that of the
same simply supported panel.
[0062] Another advantage is that a panel can have a substantial
increase load capacity without thickening its structural
section.
[0063] Another advantage is that panels may be created to cover
numerous spans to utilize the existing increased load capacity of
inside spans which is presently wasted.
[0064] Another advantage is that a low cost spray-up process may be
used to manufacture comprehensive building panels.
[0065] Another advantage is that frame members may be much thinner
since the frame member's sides can support a panel and thinner
frame members can be supported by the panel's dropped section.
[0066] Another advantage is that a prefabricated slotted panel may
have its load capacity increased multiple times by simply being
sufficiently bonded to frame members.
[0067] Another advantage is that thin ribbed panels can be made
structurally sufficient and have a substantial increase in load
capacity by being filled with and bonded to frame members with
polyurethane foam.
[0068] Another advantage is that a fixed/continuous/dropped
condition can greatly reduce thermal expansion and contraction on
susceptible claddings.
[0069] Another advantage is that the new conditions induced on a
panel act in series such that each incremental increase in load
capacity is compounded by the next condition that can increase a
panel's load capacity by several thousand percent.
[0070] Another advantage is that a polyurethane foam bonding a
cladding to frame members creates a composite panel and the induced
conditions multiply the entire panel's load capacity as opposed to
only the foam's load capacity.
[0071] Other objects, advantages and features of the inventive
subject matter will be self evident to those skilled in the art as
more thoroughly described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0072] FIG. 1 is a frame supported continuous panel over multiple
spans.
[0073] FIG. 2 is a frame supported continuous/dropped panel over
multiple spans.
[0074] FIG. 3 is a continuous/dropped panel supported by a
rotational resistance member.
[0075] FIG. 4 is a simply supported panel over a single span with a
shortened span.
[0076] FIG. 5 is a frame supported fixed/continuous/dropped panel
with fillets.
[0077] FIG. 6 is a fixed/continuous/dropped panel with a thickened
section and fillets.
[0078] FIG. 7 is a section view of a circular
fixed/continuous/dropped panel supported by a single frame member
and with fillets as the dropped section.
[0079] FIG. 8 is a bottom view of FIG. 7 showing the circular panel
and the single, circular frame member.
[0080] FIG. 9 is a ribbed foam composite panel bonded to the top of
frame members with polyurethane foam.
[0081] FIG. 10 is a ribbed structural section with a polyurethane
foam dropped section to reinforce the ribs and the skin and induce
a fixed/continuous/dropped condition on the skin.
[0082] FIG. 11 is a perspective of a ribbed foam composite panel
bonded to frame members to induce a fixed/continuous/dropped
condition on the composite panel.
[0083] FIG. 12 is a combined ribbed foam composite panel and a
ribbed structural section that has increased load capacity for both
the panel and the cladding.
[0084] FIG. 13 is a continuous panel with a blocked rotational
resistance members.
[0085] FIG. 14 is a frame supported fixed/continuous/dropped panel
with brick cladding.
[0086] FIG. 15 is an enhanced continuous conditioned panel with
increased load capacity induced on the outside spans to correspond
to that of the inside spans.
[0087] FIG. 16 is two individual fixed/continuous/dropped panels
with a seam between them.
[0088] FIG. 17 is the two panels of FIG. 16 merged into a single
structurally continuous panel.
[0089] FIG. 18 is a slotted, rib embedded panel with a finished
cladding.
[0090] FIG. 19 is a frame supported panel notched to create a
continuous/dropped condition.
[0091] FIG. 20 is a foam core sandwich panel in a
fixed/continuous/dropped condition.
[0092] FIG. 21 is ribbed siding being attached to a frame
member.
[0093] FIG. 22 is the ribbed siding of FIG. 21 bonded to a frame
member with polyurethane foam that creates a foam composite panel
with increased load capacity.
[0094] FIG. 23 is a section view of a cladding spacer attaching
cladding to a frame member.
[0095] FIG. 24 is a section view of FIG. 23 showing a filled in
spacing.
[0096] FIG. 25 is a surface onto which cladding is positioned face
down.
[0097] FIG. 26 is FIG. 25 with a frame positioned above the
cladding.
[0098] FIG. 27 is FIG. 26 with the addition of polyurethane foam to
bond everything together.
[0099] FIG. 28 is a panel in a fixed/continuous/dropped condition
to minimize the cladding's thermal expansion and contraction.
[0100] FIG. 29 is a panel in a fixed/continuous/dropped condition
with mesh embedded in the polyurethane foam as an anti-penetration
barrier.
[0101] FIG. 30 is a perspective of the backside of a panel showing
thin frame members bonded to the panel and to the rotational
resistance members.
DETAILED DESCRIPTION ACCORDING TO THE PREFERRED EMBODIMENTS OF THE
PRESENT INVENTION
[0102] The inventive subject matter is the application of four new
conditions on weaker, lighter, thinner and less costly panels to
enable them to become stiffer, stronger and more versatile by
re-configuring the panel's shape and/or by sufficiently bonding the
panel to frame members. The newly discovered conditions are: a
fixed/continuous condition, a continuous/dropped condition, a
fixed/continuous/dropped condition and an enhanced continuous
condition. The effectiveness of these new conditions is inversely
related to a panel's flexural stiffness in that the smaller the
flexural stiffness the greater the effect the conditions have on
increasing a panel's load capacity. As a result, low flexural
stiffness and typically non-structural materials, such as foam
insulation, may be converted into structural panels to facilitate a
new generation of multi-functional structural panels.
[0103] Several tests were undertaken on panels made of a low
modulus of elasticity materials or panels with a low flexural
stiffness. In one test, a simply supported 16 inch wide and three
inch thick EPS foam board was load tested over a 16.5 inch span and
found to carry 9.3 psf before deflecting about 0.07 inches (0.07
inch deflection.apprxeq.16.5 inches divided by 240). The same 16
inch wide foam board was then glued to the sides of two frame
members spaced 16.5 inches apart with a polyurethane foam poured
into a 1.25 inch deep by 0.25 inch wide gap between the sides of
the frame members and the foam board. When load tested, the EPS
foam board carried a uniformly distributed load of 44 psf before
deflecting 0.07 inches. As such, the fixed EPS foam board carried
4.7 times, or a 370% increase in load above the simply supported
foam board.
[0104] The finding that an EPS foam panel's load capacity can be
increased about 400% if it is sufficiently bonded, i.e. fixed, as
opposed to nailed to frame members is consistent with the fixed
boundary condition from fundamental beam theory used to predict
deflection. This finding was unexpected since EPS foam has such a
low modulus of elasticity as compared to steel and reinforced
concrete with which fixed boundary conditions are well known.
[0105] The testing continued on the EPS foam board by cutting the
1.25 inch deep adhesive bond along both frame members by about 0.25
inch and then testing for load carrying capacity. When the adhesive
bond was cut back from 1.25 inches to a one inch deep bond, the EPS
foam board could only carry about a 27 psf load before deflecting
to 0.07 inch and when the adhesive bond was further cut to a 0.75
inch deep bond only a 19 psf load was carried. This continued with
a 0.5 inch deep adhesive bond supporting a 17 psf load and to a
0.25 inch deep adhesive bond having a 15 psf load carrying
capacity, all before deflecting 0.07 inch. Finally, when the EPS
foam board was only slightly bonded to the frame members it carried
the same load it carried when simply supported.
[0106] From this it became evident that the foam board's load
carrying capacity was directly related to the degree or the
strength of the adhesive bond between the foam board and the frame
members. As such, the fixed boundary condition actually has degrees
of bonding strength that result in degrees of increases in load
capacity. Depending upon the bonding strength the degree of
increase in load capacity ranges from zero, where the bond is
insufficient to prevent rotation, up to about a 400% increase in
load capacity induced by a fully fixed boundary condition. For
clarification purposes, a fixed boundary inducing a 400% increase
in load capacity is herein referred to as a "fully fixed boundary".
Otherwise a "fixed boundary" condition will mean that some increase
in load capacity is present as induced by the fixed boundary
condition.
[0107] As such, testing revealed that both a minimum bond must be
present and that a direct relationship exists between the bonding
strength and the amount of load capacity increase attained by a
fixed boundary condition. This means that the degree by which a
panel is bonded to the frame members can be predetermined and
enables the regulation of the panel's load capacity. It also means
that other adhesive materials may be used since the polyurethane
foam was used such that the type of adhesive material was
irrelevant as long as it's capable of providing a sufficient bond
between the foam board, as a panel, and the frame members.
[0108] Four types of foam boards were tested: expanded polystyrene
(EPS), extruded polystyrene foam (XPS), polyurethane foam (two
pound density) and a paper/plastic coated EPS panel. Two pound
density polyurethane foam bonded to claddings with and without ribs
was also tested, as was plywood up to 0.35 inch and thin plastic.
From this testing all of the panels performed similarly and all of
the foam panels attained about a 400% load capacity increase, or
more, when sufficiently bonded or fixed to the frame members. The
0.35 inch and 0.22 inch thick plywood panels did attain an
increased load capacity from the fixed boundary condition, although
far below 400%. The polyurethane foam board began as a two part
liquid that was poured in place and expanded to bond to the frame
members and to the cladding material while transforming itself into
a solid panel. The references to calculations and predicted loads
as used herein refer to the utilization of the appropriate simply
supported, continuous conditioned and fixed boundary conditioned
deflection formulas.
[0109] Bonding a panel to frame members does not necessarily induce
a fixed boundary condition. Rather, a sufficient bond is necessary
and testing showed that bonding strength is a crucial factor in the
inducement of a fixed boundary condition on a panel to increase its
load capacity. Bonding strength is determined by the bonding
material's bonding capacity, multiplied by the size of the bonding
area between the panel and frame member. For example a polyurethane
foam with a 30 psi bonding capacity applied over two square inches
of bonding area equals 60 lbs (pounds) of bonding strength between
the panel and frame member. Each continuous panel has an interface
or contact area on at least the frame member's top edge and along
the frame member's sides when a dropped section is present.
Interface is the amount of panel to frame member contact area over
a section view of the frame member and is stated per inch of the
panel to frame member border which is transverse to the interface.
For example a 24 inch by 110 inch continuous panel over seven frame
members that have a two inch wide top edge and spaced 16 inches
apart (spans) has a 24 inch border with each frame member. The
interface is two square inches, the width of the top edge, for each
of the 24 inches of border. If the panel has a one inch dropped
section on both sides of the frame members, the interface increases
to four square inches per inch of border. The bonding area is the
amount of the two or four square inches respectively that is
actually sufficiently bonded.
[0110] In order to carry or support an increased load using the
fixed boundary condition, it is important that the panel be "fixed"
to the frame members. Fixed is herein defined as a sufficiently
high bond or bonding strength between the panel and frame members
that induces a fixed boundary condition on the panel. Sufficiently
bonded is herein referred to as being fixed. Bonding technique is
any bonding material and/or technique that can be used to prevent a
panel from rotating. Bonding materials include any type of adhesive
or other material that can cause a bond between a panel and frame
member. An example of a technique is a panel's dropped section,
tightly fitted between the sides of two frame members that prevents
the panel from rotating. Bonding techniques are material
appropriate in that some bonding techniques only apply to certain
panel and/or frame member materials. An adhesive or an adhesive
bond are types of bonding technique.
[0111] In order to achieve a sufficient bond it is important that
the bonding technique has a minimum bonding capacity of at least 10
psi and preferably at least 15 psi and more preferably at least 20
psi and even more preferably at least 25 psi. The problem with
bonding capacities of less than 10 psi is that they require larger
bonding areas to induce a sufficient bond in most situations. Since
steel can be a panel material and welding is a bonding technique,
the maximum bonding capacity is that of a steel weld on stainless
steel or about 60,000 psi.
[0112] Testing found that the bonding strength required for any
degree of a fixed boundary condition is a multiple of the load to
be carried and the multiple increases as the span increases. In one
test two, two inch polyurethane foam panels were bonded to the
sides of frame members with a 240 lb bonding strength. The first
panel had a 14.5 inch span and the second panel a 22.5 inch span.
The 14.5 inch panel carried a fully fixed boundary condition load
of 48.2 psi until the bond was decreased to about 225 lbs after
which the bond was insufficient to support the 48.2 psf load. At
the 225 lb bonding strength, the bond to load factor was 46 (225
divided by 4.9 lbs per inch). When the 22.5 inch panel was tested,
it supported 11.9 lbs, which was less than a fully fixed boundary
condition of 12.8 psf. The 22.5 inch panel had a bond to load
factor of 129 (240 divided by 1.86 lbs per inch), which is 2.8
times the 46 bond to load factor for the 14.5 inch span.
[0113] In one embodiment of this inventive subject matter a fixed
boundary condition is combined with a continuous condition to
induce an increase in load capacity on a frame supported panel.
FIG. 1 shows a panel 1 comprised of polyurethane foam 7 bonded to a
cladding 23 to create a composite panel 1 that is also bonded to
the top edge 26 of frame members 3. The panel 1 is continuous over
two or more spans 6 and, as a continuous panel, the entire panel 1
consists of a continuous section 18 that is above the top edges 26
and outside the space 4 formed between the frame member's sides 25.
Assuming the polyurethane foam 7 is fixed to the top edge 26 of the
frame members 3, a fixed boundary condition is induced on both the
polyurethane foam 7 and the composite panel 1. The fixed boundary
condition induces an increased load capacity that enables the panel
1 to support a greater load 11 than possible by the continuous
condition. Load 11 is shown in the drawings by a downward pointing
arrow . FIG. 1 also shows the panel 1 and frame members 3 comprise
a structural section 10 with a thickness 5. A rotational resistance
member 34 is shown fastened 2 to the frame member's bottom edge 27
to enable the panel 1 to carry the increased load capacity. While
the foam 7 in FIG. 1 is a self-bonding polyurethane foam, it may be
any type of foam that is sufficiently bonded in any manner to the
cladding 23 and is thereby fixed to the frame members 3.
[0114] Combining the fixed boundary condition with the continuous
condition is herein called a fixed/continuous condition. Testing
was conducted on several fixed/continuous conditioned panels to
determine how the combined conditions affect load capacity as
compared to a simply supported and a continuous conditioned panel.
The first test was of one inch thick by 3.75 inch wide by 17.5 inch
long polyurethane foam panels with a 79 psi flexural stiffness and
supported by 2.times.4 frame members and rotational resistance
members. When simply supported over a 14.5 inch span, the panel
supported 1.2 psf load before deflecting 0.06 inch (L/240). This
was consistent with the calculated load for a 950 psi modulus of
elasticity polyurethane foam. When the same panel was bonded to the
top of the frame members using the same polyurethane foam with a
bonding capacity of 30 psi, the panel supported 6.9 psf over the
single 14.5 inch span before deflecting 0.06 inch. Therefore, the
fixed panel carried 5.7 psf more or a 475% increase over what the
simply supported panel could support. This was unexpected in that
it is more than a 400% fixed boundary increase and because typical
two pound polyurethane foam was found to produce a sufficient
bonding strength to induce a fully fixed boundary condition on
itself.
[0115] Similar testing was performed on an XPS foam board and a
plywood panel. A 0.75 inch thick by 8 inch wide XPS foam board with
a 77 psi flexural stiffness and spanning 24 inches. The foam board
carried 0.25 psf when simply supported and 2.2 psf when bonded to
the 1.5 inch top edge of frame members with two pound polyurethane
foam that has a 30 psi bonding capacity. Therefore a 45 psi bonding
strength produced a 780% increased load capacity over the simply
supported panel, far more than a 400% increase theoretically
possible from a fully fixed boundary condition. The plywood panel
was a 0.344 inch thick by 8 inch wide by 24 inch long panel with a
flexural stiffness of about 5,766 psi and was tested over a 24 inch
span. When simply supported the plywood carried 25.6 psf. The panel
was then bonded with an eight pound polyurethane foam to a 3.5 inch
frame member top edge for a bonding strength of 420 psi (120 psi
times 3.5 inches), the panel carried a 48.7 psf load over the same
span which was a 90% increase over the simply supported load.
[0116] From the above, increasing the load capacity of the XPS foam
board was much easier than for the plywood. While the XPS foam
board needed only 45 psi bonding strength to induce a 780% increase
in load capacity, the plywood needed 420 psi bonding strength to
induce only a 90% increased load capacity. From this it is evident
that the higher a panel's flexural stiffness, the greater the
necessary bonding strength to induce a fixed boundary condition of
the panel. However, all of the various foams, plastic and wood
panels were able to show substantial increases in load capacity
over different spans when induced with a fixed/continuous
condition.
[0117] Testing was conducted for several continuous panels with
uniformly distributed loads over two equal spans. The first test
was of a one inch thick by 3.75 inch wide by 35 inch long
polyurethane foam panel in a continuous condition over three
2.times.4 spaced apart frame members creating two 14.5 inch spans.
This panel supported 2.9 psf over each span before deflecting 0.06
inch, which is 141% of the increase over the simply supported load.
When bonded with two pound polyurethane foam to the top of the
three frame members the fixed/continuous panel supported 9.8 psf
which is a 238% increase over the 2.9 psf continuous panel's
capacity. When bonded with an eight pound polyurethane foam the
panel supported the same load as the two pound foam indicating that
the two pound foam's bond was sufficient to induce a fully fixed
boundary condition on the panel and any additional bonding strength
was of no benefit. Finally, a narrow, intermittent strip of two
pound polyurethane foam was used to bond the continuous panel to
the frame members and the panel was only able to support 2.9 lbs
over the spans, the same as the unbonded continuous panel.
[0118] From the above tests, the one inch fixed/continuous panel's
9.8 psf load capacity was a 717% increase over the same one inch
simply supported panel's 1.2 psf load capacity over the same span.
This means that a fixed/continuous conditioned panel can have a
higher load capacity increase than either a continuous panel with a
maximum of a 141% increase, or a fixed boundary conditioned panel
with a maximum load capacity increase of 400%, or both combined at
a 540% increase. This was an unexpected result, and even more so
since it was attained with a two pound density polyurethane foam
bonding itself to frame members.
[0119] In another embodiment a panel's continuous section is
configured with a dropped section over the span to induce an
increased load capacity on the panel. This new configuration is
called a continuous/dropped condition and induces a substantial
increase in the panel's load capacity without increasing the
structural section's thickness and/or enables a thinner section
without sacrificing load capacity. FIG. 2 shows the same panel as
FIG. 1 except the polyurethane foam 7 has been thickened between
the frame members 3 to add a dropped section 19 that is in the
space 4 between the frame member's sides 25. As such, the composite
panel 1 comprised of a cladding 23 and the foam 7 is both
continuous over, as a continuous section 18, and dropped between
the frame members 3, as a dropped section 19, to form a
continuous/dropped panel condition. This results in a thickened
polyurethane foam 7 while the thickness 5 of the structural section
10 remains the same. In addition, the polyurethane foam 7 has a
much larger bonding area 14 by the interface with the frame
member's top edge 26 and sides 25. The dropped section can be any
thickness, i.e. depth, and preferably of at least 0.10 inch thick,
more preferably at least 0.25 inch thick, even more preferably at
least 0.50 inch thick, even still more preferably at least 0.75
inch thick and still even more preferably at least 1 inch thick.
The dropped section's maximum thickness is 17.98 inches which is
the panel's maximum thickness of 18 inches less the 0.02 inch
minimum continuous section thickness.
[0120] Assuming a sufficient bond between the panel 1 and frame
members 3, the panel 1 in FIG. 2 is herein referred to as having a
fixed/continuous/dropped condition which combines the
continuous/dropped configuration with a fixed boundary condition on
the panel 1. The panel 1 may be fixed to the top edge 26 and/or one
or more sides 25 of the frame members 3 to induce a
fixed/continuous/dropped condition. Such a condition induces a
substantial increase in load capacity on the panel, enabling it to
carry a greater load 11, and thereby the need for rotational
resistance members 34 fastened 2 or otherwise attached to the frame
member's bottom edge 27. While the continuous/dropped configuration
exists with or without the frame members in place, the
fixed/continuous/dropped condition is only induced on the panel
when the frame members are fixed in place and influence the load
carrying capacity of the panel. If the panel 1 in FIG. 2 was not
fixed to the frame members 3, it would have a continuous/dropped
condition.
[0121] In one test of a single spanned panel with a
fixed/continuous/dropped condition, a 16 inch wide foam composite
panel comprised of 1.9 inch thick polyurethane foam with a 0.03
inch plastic cover (cladding). The panel's continuous section
comprised of one inch foam with the plastic cover and fixed to the
top edges of two frame members spaced 14.5 inches apart. The
panel's dropped section comprised 0.9 inch of foam which was fixed
to the sides of the two frame members facing each other. The one
inch continuous section was predicted to carry 1.2 psf when simply
supported and a 1.9 inch thickened panel was predicted to carry 8.2
psf simply supported and 41 psf as a fully fixed boundary panel.
However, when the 1.9 inch thick fixed/continuous/dropped panel was
load tested it carried a 113 psf load, a 176% increase over the 41
psf predicted fully fixed boundary condition, a 1,278% increase
over the 8.2 psf thickened panel and a 9,317% increase over the 1.2
psf continuous section.
[0122] Testing was also conducted on several 4.5 inch thick
structural sections comprised of a one inch polyurethane foam panel
over the top of 1.5 inch wide by 3.5 inch deep frame members for
both single and multiple spans. One set of panels were simply
supported or continuous panels comprised of a one inch thick
section of foam supported by and/or continuous over the top edge of
frame members. A second set of panels were continuous/dropped
panels that had a one inch continuous section over the frame
members and a one inch dropped section that thickened the panel to
two inches between the frame members. The spans were all 14.5
inches and the frame members were supported by rotational
resistance members to prevent frame member rotation.
[0123] The first test was of a 3.75 inch wide by 17.5 inch long,
one inch thick simply supported panel over a single 14.5 inch span
that carried 1.2 psf before deflecting 0.06 inch. A second test was
of a 17.5 inch long simply supported continuous/dropped panel over
a 14.5 inch span with a one inch continuous section and a one inch
dropped section. This panel carried 7.4 psf or a 517% increase in
load capacity over the one inch simply supported panel. In another
test, the one inch thick.times.17.5 inch long panel was bonded to
the top edges of the frame members with two pound polyurethane foam
to induce a fixed/continuous condition on the panel. This panel
carried 6.9 psf, about a 475% increase from its 1.2 psf simply
supported. The continuous/dropped panel was then fixed to both the
top edge and the sides of the frame members facing each other to
induce a fixed/continuous/dropped condition on the panel which
supported 33.1 psf. As such, the fixed/continuous/dropped
conditioned panel over a single span produced an increased load
capacity of 2,658% over the 1.2 psf carried by the same simply
supported panel and a 380% increase over the 6.9 psf supported by
the same panel in a fixed/continuous condition. The 33.1 psf was
also a 347% increase over the 7.4 psf continuous/dropped panel and
was 248% above the predicted load of 9.5 psf for a simply supported
2'' thickened section.
[0124] The same panels were then lengthened (spliced) with the same
polyurethane foam to 35 inch long and positioned to be continuous
over two equal 14.5 inch spans. In these tests, the one inch thick,
unbonded continuous panel carried 2.9 psf, which was a 141%
increase over the single span, as predicted. When the continuous
panel was bonded to the top edges of the frame members with two
pound foam to induce a fixed/continuous condition on the panel, it
was tested to carry 9.8 psf. Testing of the same lengthened
continuous/dropped panel resulted in it carrying 17.5 psf with the
dropped section tightly against the frame member's sides and 11.9
psf when a 0.12 inch gap existed between the dropped section and
the frame member's sides. When the continuous/dropped panel was
fixed to the top edge and sides of the frame members with a two
pound foam to induce a fixed/continuous/dropped condition on the
panel, it was able to support 36.5 psf over each span. As such, the
fixed/continuous/dropped conditioned panel over two spans produced
an increased load capacity of 1158% over the continuous panel's 2.9
psf and 272% above the 9.8 psf supported by the fixed/continuous
panel. The 36.5 psf was also a 207% increase over the 11.9 psf of
the continuous/dropped panel with the gap, indicating less than a
fully fixed boundary condition. The 36.5 psf capacity was also 60%
above the predicted load capacity of 22.8 psf for a simply
supported two inch thickened section over two spans.
[0125] The dramatic increases in load capacity induced on a panel
by the fixed/continuous/dropped condition were unexpected because
they are far above the 141% increases from a continuous condition,
or the 400% increase from a fixed boundary condition or even the
272% increase over the fixed/continuous conditioned panel. The
fixed/continuous/dropped conditioned panels also had significant
increased load capacities over the fixed/continuous panel, the
continuous/dropped panel and even over the continuous panel having
its continuous section the same thickness of a continuous/dropped
panel's thickened section. Not only does the dropped section
increase the panel's load capacity, it also increases the interface
which enables more bonding area to further increase the fixed
boundary condition.
[0126] A 0.344 inch thick plywood panel was also tested with the
fixed/continuous dropped condition over a 48 inch span. When simply
supported the eight inch wide panel carried 2.4 psf and when bonded
to frame members with a 180 psi bonding strength it carried 7.1
psf. This was a 200% increase for a fixed/continuous condition.
When a one inch layer of polyurethane foam was bonded to the
plywood as a dropped section, the fixed/continuous/dropped
conditioned panel carried 8.4 psf over the 48 inch span, a 250%
increase in load capacity over the continuous section's 2.4
psf.
[0127] As a result of this and other testing all of the low modulus
of elasticity materials or panels having a low flexural stiffness
had an increased load capacity induced on the panel with a
fixed/continuous/dropped condition. This applied to all foams,
plastic, wood and other materials.
[0128] As demonstrated above, a panel's load capacities from the
various existing and new conditions can be compared to one another.
While the existing simply supported, continuous and fixed boundary
conditions all have mathematical relationships, the new conditions
must be load tested until more definitive relationships are
determined. Since the fixed boundary condition is variable, based
upon bond strength, it is more meaningful to compare the increased
load capacities induced on panels by the new conditions with the
load capacities of simply supported or continuous conditioned
panels.
[0129] A panel configured with a dropped section has a different
flexural stiffness for the part of the panel that is over frame
members and for part of the panel that is the thickened section
over the span. Since the dropped section may or may not be bonded
to the continuous section, a panel with a dropped section may have
a different flexural stiffness for the continuous section, the
dropped section and for the combined continuous and dropped
sections, i.e. the thickened section. Additionally, a panel's load
capacity over a span may also be separately determined for the
continuous section only, the dropped section only or for the
thickened section. This applies regardless of whether the panel is
simply supported or continuous and whether or not the continuous
and dropped sections are bonded together. Fillets are not included
in determining flexural stiffness.
[0130] As such, a simply supported and a continuous conditioned
panel both have a continuous section that has a load capacity over
each span. This enables the increased load capacity of panels
induced with the continuous/dropped or the fixed/continuous/dropped
conditions to be compared to the same panel's continuous section.
This comparison determines the amount of increased load capacity
provided by inducing the new conditions on the panel. The increased
load capacity induced over a panel's spans by the new conditions
may be induced over the outside spans or over one or more spans, or
preferably over two or more spans or more preferably over three or
more spans or even more preferably over at least half of the spans
and still more preferably over substantially all of the spans or
even more preferably still over all of the panel's spans. The
increased load capacity induced by a fixed/continuous/dropped
condition may also be compared to the load capacity of the panel's
unfixed thickened section.
[0131] In another embodiment a panel with the continuous/dropped
condition can derive some or all of its increase in load capacity
from rotational resistance members. For example, a
continuous/dropped conditioned panel 1 is shown in FIG. 3 comprised
of a continuous section 18 continuous over the frame member's top
edge 26 and a dropped section 19 between the frame member's sides
25 and in contact with the continuous section 18. The continuous
section 18 and the dropped section 19 may be of the same or
different material and may or may not be bonded to one another.
Also shown is a rotational resistance member 34 that is fastened 2
or otherwise bonded to the frame members 3 and in contact with the
dropped section 19. As a result of this configuration the panel 1
has a continuous/dropped condition that increases the load 11 it
can carry by virtue of the support, i.e. bearing capacity, provided
by the rotational resistance member 34 to the dropped section 19.
The amount of increase in load capacity can be wholly or partially
dependent upon the load capacity of the rotational resistance
members 34. As an alternative, the continuous section 18 and/or the
dropped section 19 of FIG. 3 may be fixed to the frame members 3 to
induce at fixed/continuous/dropped condition on the panel 1.
[0132] Another embodiment is based upon the discovery that the
panel's dropped section may be shaped to further or more
efficiently increase the panel's load capacity. For example, FIG. 4
shows an XPS foam board 9, tested as a panel 1 supported by two
frame members 3 spaced 24 inches apart and load tested to carry
0.25 psf before deflecting 0.10 inch (L/240). However, when a
buildup 13 of polyurethane foam 7 was bonded to each frame member 3
and the foam board 9, the same XPS foam board 9 carried a 4.5 psf
load 11 over the 24 inch span 6. This is a 1,700% increase in load
capacity above the 0.25 psf simply supported load and required a
rotational resistance member 34. A similar test was done with 0.344
inch plywood and the same buildups. In that test simply supported
plywood over an 18 inch span supported 40 psf and when 3.5 inch
fillets were added as a fixed dropped section, the
fixed/continuous/dropped plywood panel supported 147 psf over the
same span, a 267% increased load capacity.
[0133] Such a substantial load capacity increase was caused by two
factors. First, the polyurethane foam provided a sufficient bond to
induce a fixed boundary condition that increased the foam board's
load capacity. Second, the buildup was of a sufficiently strong
material to function like a ledge attached to the frame member that
effectively shortened the span between frame members. This is
validated by the beam theory formulas where the calculated load for
a fully fixed boundary condition for this XPS foam board over a
15.8 inch span is 4.5 psf, the same as obtained from the tested
panel. Although, while the polyurethane foam fillets maximized
shortening the span and inducing a fully fixed boundary condition
on the XPS foam board, the same fillets were less effective on the
0.344 inch thick plywood in that a fully fixed boundary condition
over an 11 inch span should have carried a 180 lb load.
[0134] The buildups 13 of FIG. 4 are basically large fillets that
can be placed on one or both sides of the frame members. FIG. 5
shows a continuous panel 1 comprised of a cladding 23 with fillets
12 bonded to the bottom of the cladding 23 to create a
fixed/continuous/dropped panel. The fillets 12 are also bonded to
both sides 25 of the frame members 3 to effectively shorten the
span 6 between frame members 3 and thereby increase the panel's 1
load 11 capacity even more. In addition, when fillets 12 are bonded
to both the panel 1 and the side 25 of the frame members, they
increase the bonding area 14 which increases the bonding strength
and thereby induces a greater fixed boundary condition to further
increases the panel's load capacity.
[0135] As such, both a simply supported and a continuous panel can
be converted into a fixed/continuous/dropped conditioned panel by
the addition of fillets 12 bonded to the sides 25 of frame members
and optionally bonded to the bottom of the simply supported or
continuous panel 1. When this occurs, the panel 1 is then comprised
of a continuous section 18 and a dropped section 19 with the
dropped section consisting of fillets 12. A rotational resistance
member 34 will be required to prevent frame member 3 rotation from
the increased load 11. Therefore, a panel may have a single dropped
section, when over a single span, or multiple dropped sections when
a panel is continuous over several spans and/or multiple dropped
sections such as two fillets within each span or the continuous
section having a corrugated shaped bottom that extends into the
dropped section area. As a result, a panel may have one or more
dropped sections between said frame members.
[0136] Fillets are herein defined as a distinguishable strip or
intermittent strips of any material capable of bonding to the sides
of frame members in order to support a continuous panel.
Distinguishable means the fillet can be distinguished from the
frame member. For example welds are considered to be
distinguishable whereas molded or integral cast fillets on a frame
member are not. Fillets may have a self bonding or self-adhesive
capability such as polyurethane foam or otherwise adhered to frame
members and optionally adhered to the panels. When not adhered to
the panels the fillets can effectively shorten the span between
frame members. As such, in order to support a continuous panel,
fillets must be of such material or composition, i.e. material
appropriate, capable of effectively shortening the span and
optionally of sufficiently bonding the panel to the frame members
to induce a fixed boundary condition on the panel. Since the
fillets are bonded to the sides of frame members, they are
considered a dropped section in and of themselves as shown in FIG.
4 or they may extend the dropped section as shown in FIG. 6. In
foam backed panels fillets may be bonded to the continuous
section's foam and thereby add a dropped section, or bonded to the
dropped section's foam and thereby extend the dropped section, or
they may be unbonded to the continuous section and simply provide a
support structure on which the continuous section bears.
[0137] Since fillets are included as a panel's dropped section and
used to increase the load capacity of the panel's continuous
section, a continuous section may span as much as 100 inches and
still have its continuous section's load capacity increased by 100%
or more by adding fillets. For example, a 6 inch polyurethane foam
board with a 1,200 psi modulus of elasticity can carry one psf over
a 100 inch span with a 0.417 inch deflection as simply supported.
Bonding the panel to frame members and adding eight inch fillets to
both ends effectively shortens the span to 84 inches and enables
the panel to carry two psf, a 100% increase in load capacity. Or,
if 12 inch fillets are used, the span is effectively shortened to
74 inches and the panel can carry three psf with the same 0.417
inch deflection, which is a 200% increase in load capacity above
that of the continuous section. In both cases the panel is 18
inches or less thick, which is the maximum panel thickness.
[0138] FIG. 6 shows a structural section 10 having a
fixed/continuous/dropped panel configuration with a continuous
section 18 over the top edge 26 and comprised of a cladding 23
bonded to foam 7. The panel's dropped section 19 is comprised of
foam 7 extending from the continuous section 18. The foam 7 is
fixed to the frame members 3 and thereby a fixed/continuous/dropped
condition is induced on the panel 1. Fillets 12 extend the dropped
section 19 along the sides 25 of the frame members 3. The fillets
12 increase the panel to frame interface and bonding area 14 and
effectively shorten the span 6, both of which further increase the
panel's load 11 capacity. The structural section 10 is comprised of
the panel 1, frame members 3 and the rotational resistance member
34.
[0139] A test comparing a two inch thick continuous panel with a
fixed/continuous/dropped panel having a two inch thickened section
was conducted. The predicted load capacity for a two inch thick
polyurethane foam panel over 14.5 inch spans is 9.4 psf when simply
supported, 56.4 psf for a continuous conditioned inside span (6
times 9.4) and 47 psf for a fixed boundary condition (5 times 9.4).
These predicted loads were compared to the actual loads carried by
the inside span of a continuous/dropped and a
fixed/continuous/dropped panel with a two inch thickened section
comprised of a one inch thick continuous section and a one inch
thick dropped section of polyurethane foam. When tested, the
continuous/dropped panel carried 42.4 psf on it's inside span,
which is less than the 56.4 psf for the two inch thick continuous
panel over the same span. However, the fixed/continuous/dropped
panel's inside span was able to support 75.5 psf, a 34% increase
over the two inch thick continuous panel. This demonstrates that
both inside spans can be increased by the new conditions and that
sufficiently bonding, i.e. fixing a continuous/dropped panel
substantially increases its load bearing capacity.
[0140] A panel is defined as a generally rigid surface, having some
amount of flexural stiffness, such as a sheathing that covers a
frame or frame members. The panel's outside surface, i.e. its face,
may be flat or shaped and the inside surface, i.e. its backside,
may have protrusions or indentations. A panel may be of any
material or combination of materials not herein excluded and be of
any size. Some examples of panels are: plywood or plastic sheets,
sandwich panels, wood or foam boards, siding and roof panels, rib
and similar protrusion backed panels, claddings, molded and
corrugated or any combination hereof to name a few. A panel may be
a composite panel, which is defined as a panel comprised of two or
more materials adhesively bonded together. A foam panel has foam as
its sole material and a foam backed panel is comprised of a
material with foam backing.
[0141] Due to the interrelationship of compressive and tensile
strength in a panel's rotation, it is important that a panel's
compressive and tensile strengths be relatively similar for
purposes of this disclosure. Therefore any panel comprised of 20%
or more, preferably 30% or more, still more preferably 40% or more
and even still more preferably 50% or more in volume of a material
that has a five times or greater difference between its compressive
and tensile strength, both as measured perpendicular to the face or
grain, is specifically excluded as a panel. Some of the excluded
materials include concrete, ceramics and glass, all with about ten
times more compressive strength than tensile strength. Other
materials such as glass fiber epoxy composites, tend to have higher
tensile strengths than compressive strengths.
[0142] One objective of the inventive subject matter is to increase
the load capacity of weaker, lighter and thinner panels which are
panels comprised of materials having a low modulus of elasticity or
panels with a continuous section having a low flexural stiffness.
As herein disclosed in several examples, panels comprised of low
modulus of elasticity materials such as foam, can have significant
increases in load capacity when induced with one the the new
conditions. Panels with a continuous section having a low flexural
stiffness, may be comprised of almost any material, although
materials having a high modulus of elasticity, such as wood or
metals which are generally flat, need to be much thinner to have a
low flexural stiffness. For panels that have a flat continuous
section a low flexural stiffness of the continuous section is
herein defined as less than 20,000 psi, preferably less than 10,000
psi, more preferably less than 8,000 psi, even more preferably less
than 4,000 psi and still even more preferably less than 2,500 psi.
Examples of flexural stiffness for wood having a 1,700,000 modulus
of elasticity are about: 0.52 inch thick has a flexural stiffness
of 20,000 psi; 0.41 inch thick has a 10,000 psi; 0.38 inch thick an
8,000 psi; 0.30 inch thick a 4,000 psi and 0.26 inch thick a 2,500
psi flexural stiffness. The thinner the flat wood or other material
becomes, the greater the influence that a low modulus of elasticity
material bonded to the wood, as a dropped section, will have on
increasing the resulting composite panel's load capacity. All other
continuous section shapes other than flat, may have unlimited
flexural stiffness, although the higher the continuous section's
flexural stiffness, the more difficult it is to increase the
panel's load capacity with a dropped section and/or a fixed
boundary condition.
[0143] Flat panels are defined as those whose moment of inertia can
be determined by the formula I=bh.sup.3/12 where I=moment of
inertia, b=base and h=height, and with or without composite
material transformation. As such, flat panels have two generally
flat, parallel faces with no exposed or embedded protrusions. For
example, sheets of plywood, foam boards, slabs, boards, metal
plates, rib-less sandwich panels are flat panels. Ribbed panels are
defined as a single skinned panel having protrusions such as ribs
extending at an angle from the skin, regardless of whether the
protrusions are molded or otherwise bonded to the skin or are bent,
corrugated or otherwise shaped from the skin and results in panel
with an increased moment of inertia resulting from such non-flat
shape.
[0144] Generally, increasing load capacity for wood panels by 25%
or more begins to be difficult at about 0.35 inch thick. For
example a 0.344 inch thick plywood panel eight inches wide over a
24 inch span can carry about 19.3 psf before deflection 0.10 inch.
In order to induce a fixed/continuous condition or a
fixed/continuous/dropped condition on the panel that increases it's
load capacity by 25%, testing has shown that about 30 lbs of
bonding strength is necessary. This may be obtained with a one inch
thick dropped section of two pound polyurethane foam, although this
low modulus of elasticity dropped section does nothing except
provide a 30 lb bonding strength to bond the panel to the frame
members. A thinner dropped section or a lower bonding strength may
not reach the 25% increase. At 0.44 inch thick a wood panel can
carry about twice the load as a 0.34'' panel and thereby requires
substantially greater bonding strength that makes it unreasonable
to use as a panel.
[0145] In order to demonstrate that the new conditions clearly
provide an increased load capacity over a simply supported, a
continuous panel, a continuous section or over a thickened section
is for the increase to be large enough to be easily distinguished.
As such, a panel with one of the four new conditions must have an
increased load capacity at least 25% greater, preferably 50%
greater, more preferably 100% greater, even more preferably 150%
greater, still more preferably 200% greater, even still more
preferably 300% greater and even more preferably still 400% greater
than, i.e. above, the simply supported, continuous panel,
continuous section or thickened section to which the increase load
capacity is compared. This means that a panel's increased load
capacity of at least 25% greater than the panel's continuous
section's load capacity must result in an increased load capacity
of at least 125% of the continuous section's load capacity. For
example if a panel's continuous section has a 60 psf load capacity,
a load capacity of at least 25% greater is at least 75 psf. The
amount of increased load capacity may be predetermined.
[0146] Given the wide variety of materials and applications for
which this inventive matter can be used, some experimentation will
be necessary. However, since the objective of this inventive matter
is to only increase as opposed to maximize a panel's load bearing
capacity, there is no need for undue experimentation. Given this
inventive matter and the availability of material properties such
as bonding capacity and modulus of elasticity as well as the
existence of flexural stiffness and deflection formulas, some
indication of the degree of increased load capacity can be easily
estimated with experimentation to confirm it. It will be recognized
by those skilled in the art that as a continuous section's flexural
stiffness increases or the span increases, the percentage increase
in a panel's load capacity created by the new conditions will
decrease, until at some point the new condition's increase in load
capacity fails to reach its minimum required increase and is
thereby ineffective.
[0147] The following example demonstrates how the maximum increased
load capacity of a fixed/continuous/dropped conditioned panel may
be determined and the magnitude of the increase over the panel's
continuous section. Beginning with a panel's continuous section
comprised of a 0.5 inch thick EPS foam board having a 120 psi
modulus of elasticity resulting in a 1.25 psi flexural stiffness.
When simply supported over a uniformly loaded single 14.5 inch span
this panel can support about 0.019 psf. When continuous over two
14.5 inch spans, as a continuous section, it can support about
0.044 psf before deflecting more than 0.06 inch (L/240).
[0148] The EPS panel is induced with a fixed/continuous/dropped
condition by bonding it to the top of frame members and bonding a
two inch thick polyurethane foam dropped section, with a 1,000 psi
modulus of elasticity, to it's backside. The dropped section is
also bonded to frame member's sides to enable the
fixed/continuous/dropped panel to carry about 50 psf over each 14.5
inch span. Adding two inch fillets effectively reduces the span to
10.5 inches and thereby the panel can support about 183 psf before
deflecting more than 0.06 inch. This 183 psf load equals 1.27 psi,
which over a 14.5 inch span equals 18.4 lbs of load to the panel to
frame member interface.
[0149] Testing has shown that a two inch thick polyurethane foam
panel over 14.5 inch span has about a 46 bond to load factor to
induce a fully fixed boundary condition on the foam panel. Adding a
2.5 safety factor increases this to a 115 bond to load factor and
multiplying it times 18.4 lbs=2,116 lbs. Since the two inch thick
dropped section plus the two inch fillets provide 4 square inches
of bonding area per interface inch, a bonding material with a 529
psi bonding capacity is needed to support the 2,116 lbs per
interface inch. Presently, bonding materials with higher bond
capacities applicable to polyurethane foam ranges up to about a
1,000 psi bonding capacity with a 75 lb density polyurethane foam.
Any material appropriate bonding material having a 529 psi or
greater may be used to bond the panel to the frame members. As
such, the 183 psf increased load capacity induced on the panel by
the fixed/continuous/dropped condition is a 415, 909% increase over
the continuous section's 0.044 psf load capacity.
[0150] However, in the event a bonding material with a bonding
capacity of only 480 psi is preferred, it is possible to work
backwards from the selection of bonding capacity. For example, a
material with a 480 psi bonding capacity applied to the 4 square
inch interface has a 1,920 lb bonding strength and when divided by
the 115 bond to load factor results in a 16.7 lb interface load.
Dividing this by the 14.5 inch span and multiplying it by 144
equals a 166 psf load, which is the maximum load possible for this
bonding capacity under these conditions and results in the
fixed/continuous/dropped panel having a 377,272% increased load
capacity over the 0.044 psf load capacity of the panel's continuous
section.
[0151] A frame member is any structure that supports at least part
of a panel over a span and has at least a top edge, a bottom edge
and two sides. Frame members may be of any type, material, size or
shape and used for any application and the top or bottom edges may
be a tip or an apex. There may also be a multitude of edges such as
a channel and a multitude of sides such as a circle or polygon.
Frame members include any frame member used in any type of
structure including all building frame members such as studs,
rafters, purlins, battens, beams, columns, plates, ledger boards
and similar members. Frame members include attachments or
extensions such as flanges, mountings and supports and may also
include cladding extensions that are molded, bent or otherwise
shaped into ribs, perimeter returns or other rib-like
configurations generally perpendicular to the cladding and that
functions like a frame member. Frame members also include ribs when
the ribs are acting as frame members in a configuration that
induces a fixed/continuous and/or a continuous/dropped condition on
a foam composite panel.
[0152] A frame or framework is comprised of a single or a multitude
of spaced apart frame members, attached or unattached to one
another. A single or a multitude of frame members shall mean that
either a single frame member by itself or optionally any number of
more than one frame members may be used to support a panel. A
single frame member may be spaced apart from itself such as a
circular shaped frame member as shown in FIGS. 7 and 8. FIG. 7 is a
section view of a structural section 10 comprised of a panel 1
supported by a single frame member 3. The panel 1 is comprised of a
continuous section 18, that is over the top edge 26 of the single
frame member 3, and a dropped section 19 which is a fillet 12
bonded to the panel 1 and to the sides 25 of the single frame
member 3. FIG. 8 is a bottom view of FIG. 7 showing structural
section 10 with a circular panel 1 continuous over a single, spaced
apart frame member 3 with the fillet 12 bonded to both the frame
member 3 and the panel 1 to induce a fixed/continuous/dropped
condition on the panel 1. Since the panel 1 is continuous over and
extends beyond the outside perimeter of the frame member 3 any load
on the span will be resisted by the cantilever and the panel has a
continuous condition. Rotational resistance is provided by the
curvature of the frame member 3 which prevents it from
rotating.
[0153] As such, in another embodiment of the inventive subject
matter, FIGS. 7 and 8 shows that a panel may be continuous over and
supported by, i.e. bears on, one spaced apart frame member that
creates a single span and is in a continuous condition that has an
increased load capacity over that span. When this embodiment is
combined with the continuous conditioned panels over two or more
spans it may be said that a panel may be continuous over and
supported by one or more spaced apart frame members to create one
or more spans between said frame members and the panel has a load
capacity over the spans.
[0154] In another embodiment a single skinned ribbed panel is
comprised of a single skin, i.e. cladding, and may be a frame
supported ribbed panel and/or a ribbed structural section depending
upon how the panel is used. The frame supported ribbed panel is one
where the ribs are supported by frame members, whereas the ribbed
structural section is one where the ribs are frame members. As
such, a panel, used as a ribbed structural section, is defined as
excluding the ribs while a panel, used as a frame supported ribbed
panel, is defined as including the ribs. For purposes of this
disclosure all ribbed panels are limited to composite panels that
have both the ribs and a second material bonded to the skin's
backside and the second material is also bonded to at least some of
the rib's sides. In most cases the second material is a foam. As
used herein, the words skin and cladding are synonymous.
[0155] Testing was undertaken to determine whether the fixed
boundary condition and the continuous/fixed condition can induce an
increase in load capacity on a frame supported ribbed panel since
such panels have a relatively high flexural stiffness. Two six inch
wide ribbed panels were tested and were comprised of a twin "T"
shape with a 0.05 inch thick vinyl cladding (the skin) and two 0.05
inch wide by one inch tall ribs spaced three inches apart and 1.5
inches from each edge and perpendicular to the cladding. The vinyl
had a modulus of elasticity of about 350,000 psi and the ribbed
panel had a flexural stiffness of about 5,100 psi. The ribbed
panels were foam composite panels since the polyurethane foam was
bonded to the cladding's backside and to the ribs and thereby
bonding the ribs to the cladding. The first ribbed panel was a
continuous panel comprised of one inch thick polyurethane foam 7
bonded to the backside 8 of a vinyl cladding 23, and to the ribs 31
and supported by spaced apart frame members 3 as shown in FIG. 9. A
rotational resistance member 34 prevented the frame members 3 from
rotating. The second ribbed panel (not shown) was a
fixed/continuous/dropped panel with the same continuous section as
the continuous panel and a one inch thick polyurethane foam dropped
section and was fixed to the frame member's top edge and sides. In
both cases the ribs were bonded to the cladding with the
polyurethane foam as opposed to being molded to the cladding. The
polyurethane foam was two pound density foam with a modulus of
elasticity of about 950 psi.
[0156] The continuous panels were tested first as simply supported
over different single spans of 14.5, 22.5 and 34.5 inches
respectively, with uniforms loads until deflection reached L/240.
The load test results were 28 psf, 7 psf and 2.1 psf respectively,
which was consistent with calculated loads with the bonded ribs
performing as though they were molded to the cladding. The
continuous panels were then induced with a fixed/continuous
condition by being fixed to the top edges of the frame members
using an eight pound density polyurethane foam having a 120 psi
bonding capacity. When tested the ribbed, fixed/continuous panels
all had substantial increases in load capacity and in some cases
greater than a 400% increase. For example, the continuous panel
over 34.5 inch span carried 2.1 psf unfixed and 11.1 psf fixed,
429% increase in load capacity. Moreover, adding one inch fillets
to the one inch thick fixed/continuous panels further increased
their load capacity. For example, over the 22.5 inch span, the
continuous panel carried 7 psf, and when fixed it carried 25.6 psf,
a 266% increase, and when fixed and with fillets it carried 32 psf,
a 357% increase.
[0157] The fixed/continuous/dropped panels were also tested and
carried 170 psf, 47 psf and 13 psf respectively over the same 14.5,
22.5 and 34.5 inch spans. As such, the fixed/continuous/dropped
panels each carried over a 500% increase in load capacity above the
ribbed continuous conditioned panel. In all cases the frame
supported ribbed panels performed similar to rib-less panels with
comparable degree of increases in load capacity for a
fixed/continuous condition and a fixed/continuous/dropped
condition. This demonstrates that the same percentage increase
induced on a foam panel can be induced on a frame supported ribbed
panel and a foam composite panel, despite the ribbed panels having
a higher flexural stiffness. This finding was unexpected because
the increases were easily induced on ribbed panels having a
relatively high flexural stiffness and the foam was sufficient to
prevent the thin ribs from buckling despite up to 170 psf loads.
The 34.5 inch fixed/continuous/dropped panel was also tested over
two 15.5 inch spans and found to exhibit the same increases in load
capacity as the non-ribbed panels over two or more spans.
[0158] In another embodiment the ribbed panel is a ribbed
structural section with a composite cladding. During testing it was
discovered that ribs may function as frame members in inducing the
fixed/continuous and the fixed/continuous/dropped conditions on a
ribbed panel's skin. Basically the skin is continuous over and
bonded to spaced apart ribs and, assuming a sufficient bond, a
fixed/continuous condition is induced upon the skin. As such the
ribbed panel's skin, whether or not a composite, has an increased
load capacity.
[0159] As previously stated, both the frame supported ribbed panel
and the ribbed structural section are limited to having a composite
cladding comprised of a second material, such as foam and
preferably polyurethane foam, adhesively bonded to the cladding's
backside and to the sides of the ribs. Therefore, a ribbed
structural section has a composite cladding with an increased load
capacity induced by a fixed/continuous/dropped condition. It is
important that the dropped section be distinguishable from the
frame members for a fixed/continuous/dropped condition. Otherwise,
the dropped section may be a thickened continuous section.
[0160] FIG. 10 shows a ribbed structural section 10 comprised of a
panel 1, ribs 31 as frame members and a rotational resistance
member 34. The panel 1 is a composite panel comprised of
polyurethane foam 7 (or another foam) bonded to the backside 8 of a
cladding 23 and at least the cladding 23 is continuous over spaced
apart ribs 31 acting as frame members. The cladding 23 is bonded to
the ribs 31 and the ribs 31 may be integrally molded to the
cladding 23 or the polyurethane foam 7 or other bonding material
may be used to bond the ribs 31 to the cladding 23. The cladding 23
comprises the continuous section 18 and the polyurethane foam 7
comprises the dropped section 19 of the composite panel 1 and
therefore a fixed/continuous/dropped condition is induced upon the
composite panel 1.
[0161] This condition increases the load capacity of the cladding
23 and polyurethane foam 7 composite panel 1 over the span between
the ribs 31. While the increase in the cladding's 23 load capacity
occurs perpendicular to the ribs 31, the increased load capacity
functions in all directions. In addition, the foam 7 bonded to the
sides of the ribs 31 may stiffen the ribs 31 from buckling. Flanges
16 are also shown which increases the rib's 31 flexural stiffness.
Finally, a rotational resistance member 34 is attached to the
flanges 16 and may also be bonded to the polyurethane foam 7. In
the event the rotational resistance member 34 provides a second
face bonded to and covering substantially all of the polyurethane
foam 7, the structural section becomes a sandwich panel and is not
a structural section of this disclosure. The structural section 10
of this disclosure specifically excludes a sandwich panel structure
which requires both skins to cover substantially all of the
structure's front and back sides and the skins adhesively bonded to
a core material that is different than that of the skins.
[0162] FIG. 11 shows a perspective of the backside of a frame
supported ribbed composite panel 1 in a fixed/continuous/dropped
condition. The composite ribbed panel 1 is comprised of a cladding
23 with ribs 31 molded or otherwise bonded to the cladding 23 and
polyurethane foam bonded to the cladding's backside 8. The cladding
23, part of the foam 7 and the ribs 31 are continuous over the
frame members 3 to comprise the panel's 1 continuous section 18.
The panel's dropped section 19 consists of polyurethane foam 7
between the frame members 3, and the foam 7 also bonds the panel 1
to both the frame member's top edge 26 and the sides 25. Rotational
resistance members are not shown, although rotational resistance
may be provided by the dropped section 19 if it is deep enough to
prevent the frame members 3 from rotating.
[0163] In another embodiment a ribbed panel may be both a frame
supported ribbed panel and a ribbed structural section. FIG. 12
shows a perspective wall section with a frame supported ribbed
panel 1 comprised of polyurethane foam 7 bonded to the backside 8
of a cladding 23 and to the sides of ribs 31, thereby also bonding
the ribs 31 to the cladding 23. The ribbed panel 1 is supported by
and bonded to a top plate 28 and a bottom plate 29, which are frame
members. The ribs 31 may be fully or partially bonded to the top or
sides of the top plate 28 and bottom plate 29. The ribs 31 also
have flanges 16 on the ends for additional strengthening.
Therefore, assuming a sufficient bond, the ribbed panel is in a
fixed/continuous/dropped condition relative to the two plates which
are frame members and the panel's increased load capacity is
induced on the panel 1 parallel to the ribs 31. As such, the ribbed
panel's increase in load capacity is compared to the same ribbed
panel as simply supported since the ribbed panel is not continuous
over two or more spans. The rotational resistance for such a the
ribbed panel is provided by the foundation, slab, floor, joists,
rafters, etc. (not shown) to which the plates are bonded to and
prevent the plates from rotating.
[0164] In addition, a ribbed structural section 10 is also shown in
FIG. 12, where the panel 1 is a foam composite panel 1 comprised of
cladding 23 as the continuous section 18 and foam 7, as the dropped
section 19, bonded to the cladding 23. In this configuration the
ribs 31 are not part of the panel 1 but rather function as frame
members 3 supporting the continuous/dropped panel. Assuming a
sufficient bond, a fixed/continuous/dropped condition is induced on
the foam composite panel 1 based on the panel's continuous/dropped
configuration to the ribs 31, acting as frame members 3. While this
increase in load capacity was caused perpendicular to the ribs 31,
it still results in an increased load capacity of the panel in any
direction. The ribbed structural section's rotational resistance is
provided by the top 28 plate and the bottom plate 29, although
intermediate rotational resistance members (not shown) may also be
needed.
[0165] In order to achieve increased load capacity, it is necessary
to provide frame members with sufficient rotational resistance.
Panels induced with the new conditions use frame members to
increase their load capacity. Both the fixed/continuous and the
fixed/continuous/dropped conditions sufficiently bond the panel to
the frame members making the frame members an extension of the
panel and thereby subject to rotational forces from loads applied
to the panel. This differs from both a simply supported panel and a
continuous panel which are both free to rotate without forcing the
frame members to do likewise. Testing has shown that rotational
resistance is necessary with a fixed/continuous or a
fixed/continuous/dropped conditioned panel to attain an increased
load capacity.
[0166] FIGS. 1 and 2 show a rotational resistance member 34
attached to the bottom edges 27 of the frame members 3 to prevent
the frame members from rotating when a load 11 is applied to the
panel 1. For example gypsum board fastened 2 to the bottom edges 27
of frame members 3 in FIGS. 1 and 2 can provide sufficient
rotational resistance for most building panel load situations.
Rotational resistance can also be achieved with blocking 35 between
the sides 25 of frame members 3 that are supporting the panel 1 as
shown in FIG. 13. The blocking 35 may be for the entire depth of
the frame member 3 or only at or near the bottom edge 27. Other
types of rotational resistant members include purlins, tops of
trusses, beams, floors, foundations, joists, etc. Basically any
element that can be attached to the frame members and resist the
degree of rotation for a particular load for a particular
application may be a rotational resistance member. This includes a
fixed/continuous/dropped panel's dropped section which extends in
depth along the frame members sides. The deeper the dropped section
and/or the bond between the dropped section and the frame members,
the greater the rotational resistance.
[0167] The rotational resistance members may cover a small section
or the entire backside of the composite panel and include
fiberglass or other thickened or reinforced spray material capable
of resisting frame member rotation. Regardless of the type or
amount of rotational resistance members, it is important frame
members have sufficient rotational resistance to at least
facilitate, i.e. be capable of handling any predetermined or other
stated amount of an increased load capacity.
[0168] Cladding is defined as any panel, material or combination of
materials used to provide a cover for a framed structure. Cladding
may be of any size and shape and of any material including panels,
panel skins, siding, tiles, bricks, stones, shingles, aggregates,
stucco, fiberglass, coatings, paint and other materials and even a
foam's integral skin if the skin has a modulus of elasticity
different than the foam's core. The cladding may be a panel itself,
such as plywood or a foam board or may it be a part of a panel such
as a coating applied to a foam board. The cladding has a face, i.e.
front side or exposed side, and a backside that is generally
unexposed and may be bonded to another material.
[0169] Testing was conducted on foam composite panels comprised of
two pound polyurethane foam bonded to the backside of several
different claddings including a 0.04 inch vinyl panel, 0.344 inch
plywood and an XPS board. A variety of load tests where performed
for both a fixed/continuous and a fixed/continuous/dropped
condition on the respective panels. In all cases the composite
panels had an increased load capacity over the load capacity of a
simply supported or a continuous panel over the same spans. In the
case of the 0.04 inch vinyl cladding, the polyurethane foam
provided substantially all of the load capacity. As such this
results in the ability to use thin (around 0.125 inch) and even
ultra thin (around 0.005 to 0.05 inch) claddings that have little
or no influence on a composite panel's flexural stiffness and let
the foam provide the load capacity.
[0170] This is contrary to present construction practices where
foam is used solely as an insulation applied to structural
sheathing with little or no influence on the panel's flexural
stiffness. For example, when two pound polyurethane foam, with a
modulus of elasticity of about 1,000 psi, is bonded to 0.75 inch of
wood sheathing, with a modulus of elasticity of about 1,600,000,
the foam provides only 1% of the panel's flexural stiffness.
However, if the same two inches of polyurethane foam is bonded to
0.25 inch thick wood, the foam provides about 24% of the composite
panel's flexural stiffness. The polyurethane foam's influence is
even more dramatic when the cladding is a coating and the foam
provides 100% of the flexural stiffness.
[0171] Another way to ensure using weaker panels or the use of
material with a low modulus of elasticity is to require that the
foam provide some meaningful amount of a panel's flexural
stiffness. For example, one inch of EPS foam boned to the backside
of 0.12 inch vinyl cladding will provide about 33% of the resulting
composite panel's flexural stiffness. Or, one inch of polyurethane
foam bonded to the backside of a ribbed vinyl panel with 0.08 inch
wide by one inch tall ribs will provide about 5% of the composite
panel's flexural stiffness. Therefore in another embodiment of the
inventive subject matter, foam must provide at least 5%, preferably
at least 10%, more preferably at least 20% and more preferably at
least 30% of the flexural stiffness of a thickened section of a
foam composite or a foamed backed panel over at least half of the
panel's spans.
[0172] Due to the importance of the foam in providing part of a
foam backed panel's flexural stiffness, the foam must have a
minimal modulus of elasticity. As such, the minimum modulus of
elasticity of a foam in this disclosure is 100 psi. Beyond this,
the foam used herein may be any type of foam capable of being
formed into a rigid or semi-rigid foam board and capable of
providing at least R2 insulation per inch of thickness. In a foam
backed panel, the foam may be adhesively or otherwise bonded or
unbonded to the cladding and frame members and the foam may provide
a backing or otherwise support all or part of the cladding. The
foam may have a self bonding or self-adhesive bonding capability
such as polyurethane foam or the foam may be bonded to the cladding
and frame members with another bonding technique. In some cases it
may be desirable to use an adhesive foam in conjunction with a
separate bonding technique or material. The foam may also be of two
or more types, for example an EPS foam board used as the continuous
section 18 and a polyurethane foam used as the dropped section 19
in a continuous/dropped configuration as shown in FIG. 3. The foam
may also be optionally bonded to frame members, optionally fixed to
frame members or optionally free of an adhesive bond to frame
members.
[0173] A foam backed panel may be a composite panel with materials
adhesively bonded together or an unbonded panel wherein the
materials are not bonded together but merely stacked, or a
combination of the two panels. In all three cases, a foam backed
panel has a flexural stiffness for the continuous section and for
the thickened section over a span. A foam may provide a direct or
indirect backing to a cladding material by being in direct contact
or indirectly by having one or more other materials between the
foam and the cladding's backside. The foam may cover all of part of
the cladding's backside and the cladding may be directly or
indirectly in contact with frame members. For example the cladding
may be in the continuous section over the frame members while the
foam is in a dropped section. Although when the cladding is in
direct contact with the frame members, it has to be more
substantial than a coating or a foil paper, for example. As such
claddings, when used as the sole material in the continuous section
or the continuous section itself must be at least 0.02 inch thick,
preferably at least 0.03 inch thick, more preferably at least 0.04
inch thick and even more preferably at least 0.05 inch thick. Foam
adhesively bonded to a cladding shall also mean a cladding
adhesively bonded to the foam. For example, foam may be bonded to
the backside of a cladding or a coating or other cladding may be
applied to the foam, both of which creates a foam composite
panel.
[0174] Regardless of whether the cladding is a panel or part of a
panel, the panel's continuous section should not be more than six
inches thick. This will allow for all types of claddings to be used
as a composite panel 1, including brick 43 that can be bonded to
frame members 3 with continuous polyurethane foam 7 as shown in
FIG. 14. Rotational resistance members 34 can be used to prevent
the frame members 3 from rotating. As such, the continuous section
18 must be from 0.02 inch to 6 inches in thickness. It should be
noted that when a break or seam exists in the cladding over a span,
such as with bricks, the cladding provides little or no load
capacity to the panel. In FIG. 14 while the bricks 43 and the foam
7 comprise the panel 1 in a fixed/continuous/dropped condition,
only the foam 7 is induced since the bricks are not continuous over
a span 6. Although, in some cases a cladding that is not continuous
may impact the panel's load capacity, which can be determined by
load testing. The maximum thickness of a panel is 18 inches since
the continuous section can be 6 inches thick and it is common for
foam cavity insulation to be as much as 12 inches thick.
[0175] In another embodiment some foams such as polyurethane foam
can be applied in a continuous manner and be extended or spliced
together with newly applied foam while retaining it's structural
continuity. Structural continuity means that polyurethane foam's
structural properties, such as bonding capacity, load carrying
capacity, tensile strength, etc., are continuous from the old or
previously applied foam to the newly applied foam as though all the
foam was applied at the same time. This assumes the new foam has
the same or higher properties than the old foam. This has several
important ramifications when applied to the inventive matter.
[0176] Structural continuity enables polyurethane foam or foam
composite panels to be continuous over an unlimited number of
spans. This is important to load capacity since a continuous panel
over three or more spans has an inherent load capacity over its
inside or center spans that is much greater than the outside span's
load capacity. This is because a panel over the inside span is
continuous over adjacent spans that react to a load on the inside
span, whereas the outside spans only have a span on one side
reacting to a load. As such an inside span has spans on both sides
whereas an outside span is either a single span or has a span on
only one side.
[0177] According to continuous beam analysis, a continuous panel
over four equal spans will support about a 100% increase in load on
it's outside spans and about a 212% increase in load capacity on
it's inside spans above the panel's simply supported load capacity.
A continuous panel over three spans will support about a 89%
increase in load capacity over its outside spans as compared to a
simply supported panel and about a 285% increase in load capacity
on its inside (center) span. However, in both cases the increased
load capacity of a panel over the inside spans is wasted or
unrecognized since the weaker section of the panel, i.e. over the
outside spans, determines the panel's effective load carrying
capacity or rating. Until now, this waste of inherent load capacity
was an unrecognized problem.
[0178] One novel solution to this problem is to enlarge the panel
size so that there are a multitude of inside spans with only two
outside spans. While not practical with most materials, it is
practical with materials like polyurethane foam that can be sprayed
or otherwise applied as a continuous panel over an entire wall or
roof section. Moreover, by applying the continuous/dropped
condition to the two outside spans or shorting the outside spans,
the load capacity of the outside spans can be inexpensively
increased to correspond to that of the inside spans. This has the
effect of more than doubling the load capacity of a typical
continuous panel.
[0179] For example, FIG. 15 shows a continuous panel 1 over four
equal spans 6 created by spaced apart frame members 3 secured by a
rotational resistance member 34. The outside spans 36 have a much
thicker dropped section 19 than the inside spans 37 and thereby
have a greater increased load capacity induced by its
continuous/dropped condition while the inside spans 37 have a lower
amount of increased load capacity induced from its
fixed/continuous/dropped condition. As such, the increased load
capacity induced on the outside spans 36 by a thicker dropped
section 19 as shown in FIG. 15, corresponds to the increased load
capacity on the inside spans 37 that is induced by the existence of
continuous spans on both sides.
[0180] Testing of a polyurethane foam panel continuous over three
spans showed that when one or both of the outside spans were given
an increase in load capacity by inducing or further increasing a
continuous/dropped condition, the outside spans were able to carry
the same or even a greater load than the inside span. The same
occurred when the outside spans were effectively shortened to have
the same or more increased load capacity as the inside span.
Testing also showed that it did not matter as to whether the inside
spans were in a continuous condition, a fixed/continuous condition
or a continuous/dropped condition. In all cases it was possible to
increase the load capacity of the outside spans to correspond to
the inside spans.
[0181] For example testing showed that a two inch thick two pound
density polyurethane foam panel with a one inch continuous section
and a one inch dropped section, supported 7.4 psf over a single
span when simply supported. The same longer panel over two 14.5
inch spans supported 17.5 psf about a 141% increase in load
capacity and consistent with the beam theory formulas. However, the
same longer, unfixed panel over three 14.5 inch spans was able to
support 42.4 psf over its inside (center) span which was 473% above
the simply supported load and even higher than the 285% predicted
increase for an inside span. The load capacity was easily increased
on both outside spans of the three span panel to support 42.4 psf
or more to correspond with the inside span. When the
continuous/dropped panels were bonded with two pound polyurethane
foam to induce a fixed/continuous/dropped condition, the inside
span's load capacity increased to 60.9 psf, a 248% increase over
the 17.5 psf when continuous over two spans. When bonded with eight
pound foam the inside span's load capacity increased to 75.5 psf, a
331% increase over the 17.5 psf. In all cases the load capacity of
the panel over the outside spans was increased to that of the panel
over the inside span.
[0182] When the increased in load capacity from the enhanced
continuous condition are compared to a continuous section, the
increases are even greater. For example a one inch thick
polyurethane foam continuous panel can support 1.2 psf over a
single 14.5 inch span and 4.6 psf over the inside span of three
14.5 inch spans. However, when the above fixed/continuous/dropped
condition is induced on the panel to increase it's inside span's
load capacity to 75.5 psf, the increased load capacity is 1,541%
above the 4.6 psf of the inside span in a three span continuous
condition.
[0183] Testing was also conducted on panels continuous over six
spans to ensure the same load capacity increases from the new
conditions are applicable to inside spans that are inside other
inside spans such a the middle two spans of a panel continuous over
six spans. A 0.22 inch thick by eight inches wide by 96 inches long
plywood panel was divided into four 14.5 inch insides spans and two
13.75 inch outside spans by 1.5 inch frame members. The plywood has
a flexural stiffness of 1,530 psi and it's predicted and actual
simply supported load capacity was 23 psf. Therefore the predicted
inside span over five or more spans was a 230% increase or 75.9
psf. The plywood was bonded to the top of each frame member with
180 lb bonding strength. The fourth span from one end was the
tested inside span with the two adjacent spans having uniform
loads. The tested inside span carried 84 psf before deflecting 0.06
inch. As such, the fixed/continuous inside span carried 8.1 psf or
11% more than the same continuous conditioned inside span, which
shows that the fixed/continuous condition is applicable to any
number of a continuous panel's inside spans.
[0184] A one inch dropped section of polyurethane foam was then
added to the 0.22 inch thick plywood panel continuous over six
spans and bonded to the spaced apart frame members. The same inside
span was tested as before and carried 89.5 psf or slightly more
than the same spans without the dropped section. As such, the
fixed/continuous/dropped condition is also applicable to any number
of a continuous panel's inside spans. Although, in this case the
89.5 psf was only a 18% increase above the continuous section's
75.9 psf over the same span, consistent with the difficulty in
increasing load capacities of panels with a higher flexural
stiffness.
[0185] For purposes of this disclosure, increasing the load
capacity of the outside spans to correspond with, i.e. be about the
same as the load capacity of the inside spans, is called an
enhanced continuous condition. The enhanced continuous condition is
a panel supported by multiple spaced apart frame members with a
continuous section that is continuous over and fixed to the top
edges and/or the sides of the frame members and the spaced apart
frame members create multiple inside spans of 2 or more, preferably
3 or more, more preferably 4 or more, even more preferably 5 or
more and even still more preferably 6 or more spans with the
outside spans having an increased load capacity to correspond to
that of the inside spans. Increasing the load capacity of the
outside spans may be accomplished by inducing or increasing a fixed
boundary condition and/or by adding or increasing the depth or size
of a dropped section, and/or by shortening the outside spans. Since
increasing the load capacity of the outside spans enables the
acknowledgment and utilization of the higher amounts of load
capacity in the insides spans, the enhanced continuous condition
may be said to increase the load capacity over two or more spans or
more preferably over three or more spans or even more preferably
over at least half of the spans and still more preferably over
substantially all of the spans or even more preferably still over
all of the panel's spans.
[0186] In another embodiment regarding polyurethane foam's
structural continuity, two or more individual foam or foam
composite panels may be spliced together to form a single,
structurally continuous panel simply by applying polyurethane foam
to the seams between the individual panels. Testing has shown that
pouring or spraying polyurethane foam, of the same or greater
density of the panels to be united, into a gap between the
polyurethane foam of the respective panels, binds the panels
together as though the foam on both panels and the foam in the gap
were all applied at the same time. The polyurethane foam expands to
fill the seam gap and bonds to each panel's polyurethane foam and
cladding with the same degree of bonding capacity that the panels
were originally formed with. This means, for example, that a seam
over a span can be eliminated by filling in the seam at a latter
time with the same polyurethane foam.
[0187] Several tests were conducted whereby a polyurethane foam
panel made in a single casting had its load capacity compared to a
polyurethane foam panel comprised of two separate, cured pieces
spliced together by the same polyurethane foam. In all cases the
load capacities were the same. For example, FIG. 16 shows the
backside of two adjacent foam backed panels 1a and 1b comprised of
a cladding 23 bonded to polyurethane foam 7 which also bonds each
panel 1a and 1b to frame members 3. The panels 1a and 1b also have
continuous sections 18 over the frame members 3 and a dropped
section 19 between the frame members 3. The panels 1a and 1b in
FIG. 16 are separate and have a seam 42 between them as can be seen
by the backside 8 of the cladding 23 showing a break in the foam 7
with a seam 42 between the two panels. Depending upon the type of
cladding 23 and installation process, the cladding 23 may or may
not be continuous over the seam 42. A "seam" as herein used, is a
break in previously applied foam, either within a panel or between
panels and may be subsequently spliced with another foam to provide
structural continuity of the foam. A splice is a seam filled with a
foam that provides structural continuity between the foams on both
sides of the seam.
[0188] In FIG. 16 the claddings 23 are butted together, overlapped
or otherwise closed together, although the seam 42 is created by
the absence of or a break in the polyurethane foam 7. In FIG. 17,
the polyurethane foam 7 is poured or sprayed on the two cladding's
backside 8, at the seam 42 and expands to fill the area surrounding
the seam 42, while bonding to the two backsides 8 and to the
existing polyurethane foam 7 on both sides of the seam 42. As such,
the polyurethane foam 7 structurally bonds the two panels 1a and 1b
together. A seam 42 may exist in the continuous section 18 and/or
in the dropped section 19 and if needed, rotational resistance
members can be attached to the frame members. Assuming the panel 1a
and 1b are fixed to frame members 3 a fixed/continuous/dropped
condition is induced over all spans.
[0189] The result is that the polyurethane foam effectively spliced
the panels together as though there was never a seam between two
panel's foam. In other words, the polyurethane foam 7 spliced area
between the two frame members 3 has the same load carrying capacity
as non-spliced polyurethane foam over the same span length. This of
course excludes any load capacity provided by the cladding, since
it remains discontinuous at the seam 42 in FIG. 17.
[0190] The implication of this is that adjacent wall or roof foam
composite panels may be bonded together for structural continuity
by simply spraying polyurethane foam onto the seamed area. The
polyurethane foam not only bonds the panels together and seals the
seam with an air, vapor and moisture barrier, but it also
transforms two or more individual panels into a single panel
spanning any number of frame members. The polyurethane foam between
the frame members bonds together such that the resulting foam board
between the two frame members is in a fixed/continuous/dropped
condition with a load capacity. In other words, the polyurethane
foam splice and the polyurethane foam on both sides of the splice
becomes a single foam with structural continuity as if all three
sections where simultaneously sprayed as one panel.
[0191] This is important in those cases where the cladding's load
capacity is inconsequential and the foam providing much or
virtually all of the panel's load capacity. This process enables an
exceptionally simple method of joining panels together during
installation. It also points out that a single foam composite panel
can be created to enclose an entire building. As long as the
primary material(s) that provide the majority of the load capacity
to a composite panel is continuous, the panel is considered to be
continuous.
[0192] The foam's structural continuity also applies to the ability
to thicken polyurethane foam at any time and achieve structural
continuity through the foam's entire thickness. As such, structural
continuity thickness is obtained by adding polyurethane foam to
thicken a polyurethane foam composite panel at a later time that is
more than five minutes after the initial application of
polyurethane foam to the cladding. Regardless of when the
additional polyurethane foam is added and the foam is thickened and
has structural continuity over the entire thickness as if the foam
was applied at the same time. For example, a polyurethane foam
composite panel may be manufactured with a one inch continuous
section of foam and then installed by positioning the panel against
frame members or cladding spacers and then spraying polyurethane
foam against the continuous section's foam backside to add a
dropped section. As a result, the panel has structural continuity
from the continuous section to the dropped section as though the
foam was applied to both sections at the same time.
[0193] In another embodiment, a panel having a continuous/dropped
configuration may be prefabricated with slots for insertion of
frame members. Upon inserting the frame members into the slots, a
continuous/dropped condition is induced and if fixed to the frame
members, a fixed/continuous/dropped condition is induced on the
slotted panel. FIG. 18 shows a perspective of a slotted panel 1
having a continuous section 18, a dropped section 19 and slots 30
into which frame members are to be inserted. A roof tile designed
cladding 23 is also shown bonded to the continuous section 18,
although the panel 1 may be without a cladding. The slots may be
sized for tight fitting frame members or enlarged with side and
possibly top gaps between the panel and the frame members to allow
for insertion of a bonding material, such as polyurethane foam, to
be injected into the gap and bond the panel to the frame
members.
[0194] The slotted panel in FIG. 18 also shows ribs 31a and 31b
embedded in the continuous section 18, and the dropped section 19
respectively. The ribs 31a in the continuous section 18 are
perpendicular to and continuous over the slots 30 so as to be
supported by the inserted frame members. The ribs 31b in the
dropped section 19 are parallel to the slots 30 so as to stiffen
the panel 1 during handling. The slotted panel 1 may also be
without ribs. The slotted panel may be made of any material and may
or may not be bonded to the frame members although sufficiently
bonding the panel to frame members will induce a
fixed/continuous/dropped condition on the panel.
[0195] FIG. 19 shows a single material panel 1 with a
continuous/dropped condition created by a slot 30 such as a dado
notched out of the backside 8 of the panel 1. This enables the
panel 1 to have a continuous section 18 over the frame members 3
while also having a dropped section 19 between the frame members 3
that may be bonded to the frame member's sides 25. Assuming the
panel 1 is fixed to the frame members, a fixed/continuous/dropped
condition is induced on the panel 1. A rabbet 38 is also shown at
the corner intersection of two panels 1. Rotational resistance
members 34 are used as needed.
[0196] In another embodiment, sandwich and double faced ribbed
panels are panels of this disclosure if the panel is in a
fixed/continuous/dropped configuration with the frame members such
that the panel's outside is a continuous section and the panel's
inside is slotted to be a dropped section between frame members.
FIG. 20 shows a foam composite panel configured as a foam core
slotted sandwich panel 1 having a polyurethane foam 7 core bonded
to the outside skin 32a which is a cladding 23 to comprise the foam
composite panel. The panel 1 has a continuous section 18 over the
frame member's top edge 26 and a dropped section 19 between the
frame member's sides 25 for a continuous/dropped condition, which
becomes a fixed/continuous/dropped condition if the slotted
sandwich panel 1 is fixed to the frame members 3. The inside skin
32b is also bonded to the foam 7 and may be a cladding, a
penetration barrier or some other type of barrier between the frame
member's sides 25. The inside skin 32b may provide some degree of
rotational resistance separately or in conjunction with a
rotational resistance member 34, as well as substantially
strengthen the structural section 10 by bracing the inside of the
frame members 3. In another configuration, a typical sandwich panel
may provide the panel's continuous section while fillets bonding
the sandwich panel to the frame members are the dropped
section.
[0197] In another embodiment a panel is made structurally
sufficient for an application by inducing one of the herein
disclosed new conditions. In many cases the amount of increased
load capacity can be predetermined based on the knowledge of the
panel's load capacity before conditions are applied. In addition,
testing can be used to determine the amounts of increased load
capacity expected with different variables such as condition
applied, panel material and thickness, bonding capacity, span,
bonding area, etc., and the appropriate combination applied to
attain at least a predetermined amount. Knowledge that a certain
combination results in attaining at least some minimum amount of
increased load capacity, means that amount was predetermined. Such
testing also enables the ability to regulate and rate the
structural sufficiency of a panel by providing parameters that
results in known increases in load capacity induced on a panel by a
fixed/continuous condition and/or a continuous/dropped
condition.
[0198] The determination as to whether a panel is structurally
sufficient or not, is based upon a given deflection, load and span
as prescribed by a code, rule, specification, directive or other
requirement or desire concerning the particular structure to which
the panel is being attached. For example, a building code or an
engineer may specify that a building panel not deflect more than
L/240 when a 40 psf lateral load is applied. If L=16 inches, the
maximum allowable deflection for this 40 psf load is 0.067 inch.
This maximum allowable deflection is then used to determine the
minimum amount of load capacity necessary for a building panel to
support this load. Typically, a load capacity greater than the
minimum amount is specified in order to provide a safety or other
factor that ensures the panel meets or exceeds its load carrying
requirement. As such, in most cases it is necessary to identify and
thereby predetermine some degree of a panel's increased load
capacity to ensure it is sufficient for an application.
[0199] In another embodiment a foam composite panel bonded to frame
members may be prefabricated or fabricated in place and the foam
may be applied to the cladding or the cladding applied to the foam.
The foam composite panel bonded to frame members may be jobsite
fabricated by positioning a cladding adjacent to an erected frame
or frame members and then applying foam to the backside of the
cladding and bonding the foam to the frame members. Bonding to the
frame members may be accomplished by using polyurethane foam or by
using a separate adhesive between the foam and the frame
members.
[0200] As shown in FIG. 21, cladding 23, comprised of a ribbed 31
siding panel 24 is attached to erected frame members 3 with
fasteners 2 or other bonding. In this configuration the ribs 31
provide a spacing 44 between the cladding 23 and the frame member 3
to enable the polyurethane foam to fill in the spacing 44 and
provide a continuous condition over the frame members 3. FIG. 22
shows the siding panels 24 fully attached to the frame members 3
and polyurethane foam 7 filled into the spacing 44 and bonding to
the side 25 of the frame member to bond the siding panel 24 to the
frame members 3. Assuming a sufficient bond, the panel 1 is induced
with a fixed/continuous/dropped condition.
[0201] In another configuration of the panel being fabricated in
place, cladding spacers are situated between the panel and the
frame members to provide a space into which foam may be applied. A
cladding spacer is a structure that creates open space between the
frame members and a cladding or a composite panel. FIG. 23 is a
section view of a framed wall comprised of frame members 3 attached
to a bottom plate 29 which is attached to a foundation 46 or floor
structure. Also shown is a temporary brace 33 fastened 2 to the
foundation 46 and preferably secured at its top (not shown) and
used to support siding panels 24 while being bonding to the frame
members 3. The siding panels 24, which are a cladding, are
positioned against the brace 33 and secured by a cladding spacer 39
wedged between the siding panel 24 and the frame member 3. As a
result, a spacing 44 is created between the siding panel 24 and the
frame members 3. The cladding spacers 39 may be any material
although a small foam block is preferred so as to prevent a thermal
bridge. Once the siding panels 24 have been positioned, they may be
further secured by a clump of polyurethane foam (not shown) sprayed
between the siding panel 24 and the frame members 3.
[0202] FIG. 24 shows the same framed wall of FIG. 23, with a panel
1 comprised of polyurethane foam 7 applied to the backside 8 of the
siding panels 24, which represents the cladding 23 of this panel 1.
The polyurethane foam 7 filled in and occupies the spacing 44, to
sufficiently bond the siding panels 24 to the frame members 3. A
continuous section 18 is comprised of the siding panels 24 and the
polyurethane foam 7 in the spacing 44. The polyurethane foam 7 is
also the dropped section 19 bonded to the frame member's sides 25.
As such, the panel 1 is continuous over, dropped between and fixed
to the frame members 3 to induce a fixed/continuous/dropped
condition on the panel 1. The polyurethane foam 7 may also seal the
siding panel 24 to the bottom plate 29 and the foundation 46. The
purpose of the cladding spacers is to provide a spacing between the
cladding and the frame members that can be filled with an
insulating material such as foam. As such the cladding spacers may
be individual spacers or an elongated member fastened to the frame
members and/or the cladding.
[0203] A foam composite panel bonded to frame members may also be
prefabricated, which includes the spray-up manufacturing process.
Prefabrication begins with preparing a surface such as a platform,
worktable, backstop or form and positioning the cladding material
on the surface. FIG. 25 shows a surface 40 onto which a cladding 23
is positioned with its backside 8 up, i.e. exposed. The surface 40
may be horizontal, vertical or at some angle. The cladding 23 may
be positioned in a number of ways, depending upon the type of
material used. For example a coating material may be sprayed
against a prepared form surface 40, or an aggregate cladding may be
spread over a horizontal surface 40, or siding panels, tiles, thin
bricks or similar types of cladding 23 may be laid-out on a
worktable. The cladding 23 may also be a composite comprised of two
or more different materials or materials with different properties.
For example a polyurea may be sprayed onto a form surface 40
followed by a resin mixture poured or spayed on top of the polyurea
to comprise a composite cladding 23.
[0204] After the cladding 23 has been positioned, a frame 41 or
individual frame members 3 are positioned above the cladding 23 as
shown in FIG. 26. The frame 41 may be suspended or spacers may be
used to create a spacing 44 between the backside 8 of the cladding
23 and the frame 41. Polyurethane foam 7 is bonded to the backside
8 of the cladding to create a foam composite panel 1 as shown in
FIG. 27. The polyurethane foam 7 may be poured or sprayed onto the
backside 8 and as it expands it bonds the cladding to the frame 41
and individual frame members 3. FIG. 27 shows that both a
continuous section 18 and a dropped section 19 are present and if
fixed to frame members 3, a fixed/continuous/dropped condition is
induced on the panel 1. Fillets may be added to further increase
the panel's 1 load capacity.
[0205] There are several possible alternatives to the spray-up
process although the preferred method is spraying a polyurea or
similar coating on a form, followed by spraying or pouring on a
liquid polyurethane foam on the backside of the coating. Arranging
a frame or frame members above the coating's backside and letting
the polyurethane foam to expand and bond the coating to the frame
members.
[0206] In another embodiment both the fixed/continuous condition
and the fixed/continuous/dropped condition, when bonded to frame
members, increases a panel's uplift resistance simply due to the
bond between the panel and the frame members. The uplift resistance
is even more pronounced with ribbed panels since the ribs provide
additional bonding area as well as introducing a shear bond between
the foam and the rib's sides. Moreover, when the ribs are
perpendicular to the frame members, the bonding is extended along
the ribs.
[0207] In another embodiment the continuous/dropped conditions can
minimize the effects of thermal expansion or contraction on
cladding materials. FIG. 28 shows polyurethane foam 7 bonded to the
backside 8 of a cladding 23 to create a foam composite panel 1 that
is fixed to the frame members 3 to induce a
fixed/continuous/dropped condition on the panel 1. As such, the
panel's 1 continuous section 18 is bonded to the frame member's top
edge 26 and more importantly is thoroughly bonded to the dropped
section 19 which in turn is both bonded to and constrained between
the sides 25 of frame members 3. Since the dropped section's 19
span is relatively small, the change in linear dimension is so
small that the frame member's 3 physical presence prevents the foam
7 in the dropped section 19 from expanding. In addition, if the
foam 7 is sufficiently bonded to the frame member's sides 25, the
foam 7 in the dropped section 19 is prevented from contracting. As
a result, since the foam 7 in the dropped section 19 cannot expand
or contract, neither can the foam 7 in the continuous section 19
nor can the entire panel 1. FIG. 28 also shows a rotational
resistance member 34.
[0208] In another embodiment, a mesh is bonded to the frame members
to provide an anti-penetration layer to the panel. As shown in FIG.
29, a mesh 45 is stapled to the top edge 26 of frame members 3 and
is continuous over two or more frame members 3. Polyurethane foam 7
is applied to the backside 8 of the cladding 23 and as it expands
into a continuous/dropped configuration, the polyurethane foam 7
engulfs the mesh 45 resulting in mesh 45 being an embedded layer in
the polyurethane foam 7. The mesh 45 provides an anti-penetration
layer to the panel 1 by its attachment to the frame member's top
edge 26 which absorbs a shear force from any projectile penetrating
the panel 1. A rotational resistance member 34 is needed to prevent
frame member 3 rotation. The mesh 45 may be bonded or otherwise
attached to the frame members 3 in any fashion. The panel 1 is
induced with a fixed/continuous/dropped condition if it is fixed to
the frame members 3.
[0209] In another embodiment the continuous/dropped condition
enables thinner frame members since the dropped section's bond to
the frame member's sides can provide practically all of the
necessary panel support. In addition, the dropped section supports
the thinner frame member from buckling and can be used to prevent
the frame from racking and may provide some or all of the
rotational resistance. The dropped section can be of the same or a
different material than the continuous section.
[0210] FIG. 30 shows a perspective of a structural section 10
comprised of a thin skin, i.e. cladding 23, on the front side that
is continuous over and bonded to thin frame members 3. Also shown
is a dropped section 19, of another material, bonded to the
backside 8 of the cladding 23 to comprise a composite panel 1. The
dropped section 19 is fixed to the sides of frame members 3 to
induce a fixed/continuous/dropped condition on the composite panel
1. The dropped section 19 also reinforces the frame members 3 from
buckling. Also shown are rotational resistance members 34 bonded to
the bottom edge 27 of the frame members 3 and optionally bonded to
the dropped section 19.
[0211] Since the rotational resistance members 34 are individual,
spaced apart members, the composite panel 1 is not a sandwich
panel. A sandwich panel's increased load capacity derives from the
interaction between the two skins bonded to a core material. A
panel of the inventive subject matter obtains an increase in load
capacity by the panel's interaction with the frame members and in
particular the panel being continuous over frame members, fixed to
frame members and having a dropped section between frame members,
or any combination thereof.
[0212] From the description above, a number of advantages of some
embodiments of the stiffened, frame supported panel become
evident:
[0213] (a) The inventive subject matter enables weaker, thinner,
lighter, more versatile and less expensive materials to have their
load capacities greatly increased to enable them to used as
structural panels.
[0214] (b) The inventive subject matter enables all types of panels
to have an increased load capacities of several times and in some
cases a several thousand percent increase above the same simply
supported panel.
[0215] (c) The inventive subject matter enables polyurethane foam
bonded to a cladding and frame members to become a comprehensive
structural panel that provides a finished exterior, continuous and
cavity insulation as well as an air, moisture and vapor barrier,
increased uplift resistance and the elimination of condensation and
thermal expansion/contraction.
[0216] (d) The inventive subject matter enables fillets to be used
to increase a panel's load capacity by several thousand percent
above that of the same simply supported panel.
[0217] (e) The inventive subject matter enables panels to have
substantial increased load capacity without thickening their
structural section.
[0218] (f) The inventive subject matter enables panels to utilize
the inherent increased load capacity of inside spans which is
presently wasted.
[0219] (g) The inventive subject matter enables a low cost spray-up
process to manufacture comprehensive building panels.
[0220] (h) The inventive subject matter enables thinner frame
members since panels can be bonded to frame member's sides to
support the panel and thinner frame members can be supported by the
panel's dropped section.
[0221] (i) The inventive subject matter enables prefabricated
slotted panels to have its load capacity increased multiple times
by simply being sufficiently bonded to frame members.
[0222] (j) The inventive subject matter enables thin ribbed panels
to have a substantial increase in load capacity by being filled
with and bonded to frame members with polyurethane foam that also
prevents the ribs from buckling.
[0223] (k) The inventive subject matter enables the new conditions
induced on a panel to act in series such that each incremental
increase in load capacity is compounded by the next condition to
increase a panel's load capacity by many times.
[0224] (l) The inventive subject matter enables a
fixed/continuous/dropped condition to greatly reduce thermal
expansion and contraction on susceptible claddings.
[0225] Although the description above contains many specifications,
these should not be construed as limiting the scope of the
embodiments but as merely providing illustrations of some of
several embodiments. Thus the scope of the embodiments should be
determined by the appended claims and their legal equivalents,
rather than by the examples given.
* * * * *