U.S. patent application number 11/618731 was filed with the patent office on 2008-07-03 for method of manufacturing composite structural panels and using superimposed truss members with same.
Invention is credited to PETROS KESHISHIAN, Armen Martirossyan.
Application Number | 20080155919 11/618731 |
Document ID | / |
Family ID | 39581985 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080155919 |
Kind Code |
A1 |
KESHISHIAN; PETROS ; et
al. |
July 3, 2008 |
METHOD OF MANUFACTURING COMPOSITE STRUCTURAL PANELS AND USING
SUPERIMPOSED TRUSS MEMBERS WITH SAME
Abstract
A method of producing an engineered composite structural panel
by selecting a structural panel having at least two structural
shells, an insulating material extending therebetween, and a
plurality of truss members extending therebetween. A determination
is made if the two or more structural shells act as a unitary
composite structural panel. If the structural panel is not a
unitary composite structural panel, then parameters of the panel
are adjusted and it is further determined whether the panel is a
unitary composite structural panel. Combined truss systems for
strengthening the structural panels may be formed by combining
ladder truss members with warren truss members, by superimposing
the ladder truss members and warren truss members, and by
superimposing ladder truss members with a warren truss member and
another warren truss member that is inverted.
Inventors: |
KESHISHIAN; PETROS; (Castro
Valley, CA) ; Martirossyan; Armen; (Glendale,
CA) |
Correspondence
Address: |
THE SONI LAW FIRM
55 S. LAKE AVE SUITE 720
PASADENA
CA
91101
US
|
Family ID: |
39581985 |
Appl. No.: |
11/618731 |
Filed: |
December 29, 2006 |
Current U.S.
Class: |
52/309.11 ;
52/690; 52/745.19; 52/745.21 |
Current CPC
Class: |
E04C 2/044 20130101;
E04C 2/049 20130101; E04C 2002/045 20130101; Y10T 29/49629
20150115 |
Class at
Publication: |
52/309.11 ;
52/690; 52/745.21; 52/745.19 |
International
Class: |
E04C 5/00 20060101
E04C005/00; E04C 3/02 20060101 E04C003/02; E04C 1/40 20060101
E04C001/40; E04G 21/12 20060101 E04G021/12 |
Claims
1. A stiffened truss member for a structural panel having a pair of
wire-mesh panels connected to and separated by an insulating
material extending therebetween, the stiffened truss member
comprising: a ladder truss member having a pair of spaced-apart
elongated parallel first ladder truss bars and a plurality of
spaced-apart elongated second ladder bars extending therebetween in
perpendicular relationship to the first ladder truss bars to form a
ladder configuration; a warren truss member having a pair of
spaced-apart elongated parallel first warren truss bars and a
second warren truss bar extending at an angle therebetween in a
zigzag configuration; and wherein the ladder and warren truss
members are superimposed upon each other and being attachable to a
portion of the structural panel such that the second ladder truss
bars intersect the second warren truss bars to form a unitary
composite structural panel.
2. The stiffened truss member as in claim 1 wherein the ladder and
warren truss members are superimposed upon each other along the
first ladder truss bars and the first warren truss bars
respectively so to align the first ladder truss bars and the first
warren truss bars in parallel relationship.
3. The stiffened truss member as in claim 2 wherein the ladder and
warren truss members are attached to each other via a plurality of
retainer clips disposed at locations along the first ladder truss
bars and the first warren truss bars.
4. The stiffened truss member as in claim 1 wherein the angle is in
the range of between 40 to 50 degrees.
5. The stiffened truss member as in claim 4 wherein the angle is
exactly 45 degrees.
6. The stiffened truss member as in claim 1 wherein the first
ladder truss bars, the second ladder truss bars, the first warren
truss bars, and the second warren truss bars are fabricated from a
rigid material of a uniform thickness.
7. The stiffened truss member as in claim 6 wherein the first
ladder truss bars, the second ladder truss bars, the first warren
truss bars, and the second warren truss bars are fabricated from
steel.
8. A stiffened truss member for a structural panel having a pair of
wire-mesh panels connected to and separated by an insulating
material extending therebetween, the stiffened truss member
comprising: a ladder truss member having a pair of elongated
parallel first ladder truss bars and a plurality of elongated
second ladder bars extending therebetween in perpendicular
relationship to the first ladder truss bars to form a ladder
configuration; first and second warren truss members each having a
pair of elongated parallel first warren truss bars and a second
warren truss bar extending at an angle therebetween in a zigzag
configuration; and wherein the first warren truss member is
inverted and superimposed upon the first and second warren truss
members and being attachable to a portion of the structural panel
such that the second ladder truss bars intersect the second warren
truss bars of both the first and second warren truss members to
form a unitary composite structural panel.
9. The stiffened truss member as in claim 8 wherein the ladder
truss member, the first warren truss member and the second warren
truss member are superimposed upon each other along the first
ladder truss bars, the first warren truss bars of the first warren
truss member, and the first warren truss bar of the second warren
truss member respectively so to align the first ladder truss bars,
the first warren truss bars of the first warren truss member, and
the first warren truss bars of the second warren truss member in
parallel relationship.
10. The stiffened truss member as in claim 9 wherein the ladder
truss member, the first warren truss member and the second warren
truss member are attached to each other via a plurality of retainer
clips disposed at locations along the first ladder truss bars, the
first warren truss bars of the first warren truss member, and the
first warren truss bars of the second warren truss member.
11. The stiffened truss member as in claim 9 wherein the angle is
in the range of between 40 to 50 degrees.
12. The stiffened truss member as in claim 11 wherein the angle is
exactly 45 degrees.
13. The stiffened truss member as in claim 9 wherein the first
ladder truss bars, the second ladder truss bars, the first warren
truss bars of both the first and second warren truss members, and
the second warren truss bars of both the first and second warren
truss members are fabricated from a rigid material of a uniform
thickness.
14. The stiffened truss member as in claim 13 wherein the first
ladder truss bars, the second ladder truss bars, the first warren
truss bars of both the first and second warren truss members, and
the second warren truss bars of both the first and second warren
truss members are fabricated from steel.
15. A stiffened truss member for a structural panel having a pair
of wire-mesh panels connected to and separated by an insulating
material extending therebetween, the stiffened truss member
comprising: a pair of elongated parallel combined truss bars and a
plurality of elongated ladder bars extending therebetween in
perpendicular relationship to the combined truss bars to form a
ladder configuration; an elongated zigzag bar extending between the
combined truss bars at an angle in a zigzag configuration; and
wherein the ladder bars and the zigzag bars intersect each other at
spaced-intervals along the combined truss bars and being attachable
to a portion of the structural panel to form a unitary composite
structural panel.
16. A method of producing an engineered composite structural panel
comprising the steps of: (a) selecting a structural panel having at
least two structural shells, an insulating material extending
therebetween, and a plurality of truss members extending
therebetween; (b) determining if the two or more structural shells
act as a unitary composite structural panel; and (c) if the
structural panel is not a unitary composite structural panel, then
adjusting parameters of the panel and repeating step (b).
17. The method as in claim 16 wherein step (b) comprises the step
of calculating the buckling capacity of the shells such that
P.sub.Global>P.sub.Local and V.sub.Truss>V.sub.u.
18. The method as in claim 17 further comprising the step of: (d)
determining capacity of each of the structural shells.
19. The method as in claim 18 further comprising the step of: (e)
determining limit state of the panel by calculating a plurality of
force and eccentricity pairs such that at least one of the shells
exceeds the capacity calculated in step (d).
20. The method as in claim 19 further comprising the step of: (f)
if the structural panel is a unitary composite structural panel,
then checking shear capacity of the truss according to the formula
V.sub.Truss>V.sub.u.
21. The method as in claim 20 further comprising the step of: (g)
if the structural panel works as unitary composite panel, then
verifying connectivity between the truss members and structural
shells such that all shear load is taken by truss members.
22. The method as in claim 21 wherein step (g) further comprises
the step of: (1) verifying the pullout capacity of the unitary
composite panel; and (2) verifying the punching shear capacity of
the unitary composite panel.
23. The method as in claim 16 wherein at least three structural
shells are selected in step (a) and further comprising the step of
determining stress-strain for capacity of the unitary composite
structural panel.
24. The method as in claim 16 wherein the parameters are selected
from the group consisting of: spacing between the truss members,
number of truss members, thickness of truss members, thickness of
shells, and distance between shells.
25. The method as in claim 16 wherein step (a) comprises the steps
of: 1) selecting loads to be carried by the panel; and 2) selecting
parameters of panels.
26. The method as in claim 16 wherein step (a) further comprises
the step of: attaching a stiffened truss member for a structural
panel having a pair of wire-mesh panels connected to and separated
by an insulating material extending therebetween, the stiffened
truss member comprising: a ladder truss member having a pair of
spaced-apart elongated parallel first ladder truss bars and a
plurality of spaced-apart elongated second ladder bars extending
therebetween in perpendicular relationship to the first ladder
truss bars to form a ladder configuration; a warren truss member
having a pair of spaced-apart elongated parallel first warren truss
bars and a second warren truss bar extending at an angle
therebetween in a zigzag configuration; and wherein the ladder and
warren truss members are superimposed upon each other and being
attachable to a portion of the structural panel such that the
second ladder truss bars intersect the second warren truss bars to
form a unitary composite structural panel.
27. The method as in claim 16 wherein step (a) further comprises
the step of: attaching a stiffened truss member for a structural
panel having a pair of wire-mesh panels connected to and separated
by an insulating material extending therebetween, the stiffened
truss member comprising: a ladder truss member having a pair of
elongated parallel first ladder truss bars and a plurality of
elongated second ladder bars extending therebetween in
perpendicular relationship to the first ladder truss bars to form a
ladder configuration; first and second warren truss members each
having a pair of elongated parallel first warren truss bars and a
second warren truss bar extending at an angle therebetween in a
zigzag configuration; and wherein the first warren truss member is
inverted and superimposed upon the first and second warren truss
members and being attachable to a portion of the structural panel
such that the second ladder truss bars intersect the second warren
truss bars of both the first and second warren truss members to
form a unitary composite structural panel.
28. The method as in claim 16 wherein step (a) further comprises
the step of: attaching a stiffened truss member for a structural
panel having a pair of wire-mesh panels connected to and separated
by an insulating material extending therebetween, the stiffened
truss member comprising: a pair of elongated parallel combined
truss bars and a plurality of elongated ladder bars extending
therebetween in perpendicular relationship to the combined truss
bars to form a ladder configuration; an elongated zigzag bar
extending between the combined truss bars at an angle in a zigzag
configuration; and wherein the ladder bars and the zigzag bars
intersect each other at spaced-intervals along the combined truss
bars and being attachable to a portion of the structural panel to
form a unitary composite structural panel.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to the field of
structural panels and more specifically to improved truss members
for use with such panels and a method of manufacturing panels using
an engineered approach.
BACKGROUND OF THE INVENTION
[0002] Structural Concrete Insulating Panels (SCIP) are typically
composed of two or more structural shells that are separated with
an insulating material and connected via steel trusses. In a
typical SCIP panel, the shells are fabricated from concrete, the
insulating material is a foam and the trusses are composed of wire.
Such SCIPs are used in building homes and other structures by
relatively unskilled laborers and are pre-fabricated and sent to
the jobsite. SCIP panels are advantageous in that the same type of
panel may be used to erect walls, floors, ceilings and other panels
of a building by relatively unskilled laborers, provides good
insulation, and may be produced with environmentally friendly
materials. Disadvantageously, the cost of implementing SCIPs can
become high due to costs associated with meeting building code
requirements and manufacturing costs. The present invention
addresses those needs in the art.
[0003] Building code requirements typically require SCIPs to obtain
an International Council of Building Officials "ICBO" number (now
called International Code Council "ICC") that involves a series of
laboratory tests to test the structural capacity of the panel or
per local building department requirements' separate research
report. This is because the SCIPs are not classified as a standard
item by the building codes. In obtaining the ICBO number, SCIP
manufacturers were typically required to submit their panels for
laboratory testing and through a series of trial and error by
applying loads upon the panel to test the critical capacity and
otherwise determine the structural properties of the panel based on
the dimensions of a few panels. Such a process is time consuming
and costly for the manufacturer and until now, it is understood
that this was the only way to allow a SCIP panel to pass the
building code requirements.
[0004] In designing a SCIP, it must be determined how the two rigid
shells that make up the panel will react when under load. In a
first case, each rigid shell is treated as a separate shell member
such that each shell will fail individually when a load is placed
upon it that exceeds the capacity. In a second case, the system of
both rigid shells acting together will fail as one composite
section. In making such a determination, it is the objective to
design a SCIP that will fail as one composite section because such
a design will yield a significantly higher capacity when under
load. It is understood that there is no currently developed
methodology for allowing a SCIP designer to make this determination
without undergoing laboratory tests. This critical determination is
key to designing a SCIP that constitutes a composite section.
[0005] By approaching the design of a SCIP from an engineering
perspective, there is a long felt need in the art for determining
whether the SCIP acts as a single composite panel and for providing
a theoretical method of designing such SCIPs that conform to
building code requirements without the necessity of undergoing
expensive laboratory testing.
[0006] A typical truss employed in a SCIP is one that is made up of
a rod which is formed in a zigzag configuration between two
parallel rods with an angle of approximately 30 degrees. This is
known as a warren truss. While warren trusses are well known in
their ability to provide strengthening, their application to SCIPs
suffers from drawbacks that ultimately result in SCIPs which cannot
handle large capacities and can be improved upon.
[0007] For example, U.S. Pat. No. 6,718,712 discloses
pre-fabricated structural panels and a method of fabrication, which
utilizes commercially available panel components, such as trusses,
fillers, wire meshes, and metal ties; filler material of stabilized
organic material such as biomass or agricultural waste; and
fabrication of such panels with varying thickness.
[0008] Disadvantageously, the '712 patent uses only a warren truss
with an approximate 30 degree angle which is relatively inefficient
and uneconomical for panel construction.
[0009] Even further, the '712 patent fails to provide a method of
engineering the sizes, weights, strengths, spacing and composition
of various panel components, particularly those for concrete panel
skins, by applying an engineering approach to determining whether
the panel acts as a composite structural panel prior to designing
the panel.
SUMMARY OF THE INVENTION
[0010] The present invention provides a improved method of
designing and manufacturing a panel that is a composite structural
panel. More specifically, while it is understood that SCIPs all
well known in the art and can be manufactured according to a
variety of different ways, the current problem is that from an
engineering perspective, there is no known methodology for
designing a SCIP having two or more structural shells where the
entire SCIP acts as a unitary composite structural panel. The
present invention addresses that need by providing a novel method
of designing such a panel to determine whether the panel is indeed
a composite panel, determining the capacity of that panel, and
adding additional structure if necessary to make the panel act as a
unitary composite structural panel. It should be recognized that
the novel process of making this determination is not limited to
the panel illustrated and described but is also applicable to other
structural concrete panels so long as they share the same
characteristics of having at least two shells joined by a truss or
other strengthening device. It is also not critical to incorporate
the additional truss systems herein to practice the novel process
described herein.
[0011] By adopting the test approval method the manufacturer is
only limited to producing the size and configuration panels that it
has tested. This limits the different panel configurations that one
can manufacture due to the cost and time limitation of testing and
getting approval on any single size and configuration panel. The
present invention provides the manufacturer with the ability to
produce panels of any size and configuration so long as it meets
the general category of SCIP, without undergoing testing-based
approval.
[0012] Specifically, a panel having two or more structural shells
joined by a series of trusses or other types of connections suffers
from the problem that inadequate parameters will cause one of the
structural shells to fail independently of the other when excess
loads are placed thereupon. In that respect, a panel designed
having such individual structural shells is a weaker panel that if
the two or more structural shells are joined by the trusses but act
as one cohesive unit, or a unitary structural shell. Such a unitary
structural shell will have a set capacity and will truly act as one
cohesive unit such that excess loads placed upon the entire panel
dictate the failure rate of the panel, not the loads placed upon
the individual structural shells. The engineering theory developed
herein provides a methodology for establishing that the individual
structural shells are indeed sufficiently connected by the trusses
and overall act as one cohesive unit. Once establishing that the
panel acts as a unitary structural shell, standard engineering
principals may be applied to determine the total capacity of the
panel, which is greater than if the individual structural shells
were configured to independently fail when excess loads are placed
thereupon.
[0013] To further ensure that the panel works as a unitary
structural shell, at least three types of truss systems may be
attached to the panel to strengthen the bond between the individual
structural shells. Those truss systems include a first truss system
whereby a conventional and commercially available ladder truss may
be superimposed upon an additional truss having a rod extending
between two parallel rods in a zigzag configuration, which is also
known as a warren truss. Preferably, the ladder and warren trusses
are superimposed upon each other such that the angle bends of the
warren truss interest with the ladder truss bars.
[0014] A second type of truss system is similar to the first truss
system but includes the addition of a second warren truss that is
inverted and superimposed upon both a ladder truss another warren
truss.
[0015] In a third type of truss system, no superimposing is
necessary, and instead a combined truss system is developed which
integrates both the rod having a zigzag configuration from a warren
truss with the ladder truss in one integral unit.
[0016] These three truss systems are advantageous in that they
provide enhanced strengthening between the structural shells and
further ensure that the panel globally acts as unitary composite
structural shell.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of a SCIP having a combined
truss member attached thereto;
[0018] FIG. 2 is a elevational view of a combined truss;
[0019] FIG. 3 is a elevational view of a ladder truss;
[0020] FIG. 4 is a view illustrating the combination of a ladder
truss with a warren truss;
[0021] FIG. 5 is a view of a ladder truss combined with a first
warren truss and an inverted second warren truss;
[0022] FIG. 6 is a diagram illustrating buckling as a result of the
shells acting individually;
[0023] FIG. 7 is a diagram illustrating buckling as a result of the
shells working together as a unitary composite structure shell;
[0024] FIG. 8 is a P-M interaction diagram;
[0025] FIG. 9 illustrates the applied load P, its eccentricity e,
the compressive capacity of a shell Fc, the tensile capacity of a
shell Ft, and the parameters of the panel;
[0026] FIG. 10 is a key to notation variables used in the exemplary
calculation according to the present invention for a wall;
[0027] FIG. 11 illustrates the truss combinations of the warren
truss, a first truss system and a third truss system, and
additional sets forth the material properties for the panel;
[0028] FIG. 12 sets forth the variables used the calculations and
illustrates the parameters which may be varied to determine if the
panel is a unitary composite structural panel;
[0029] FIG. 13 illustrates the selected truss system and
calculations required for buckling capacity between truss
connection points and to determine whether the panel is a unitary
composite structural panel;
[0030] FIG. 14 is a continuation of FIG. 13 and illustrates further
calculations for determining whether the panel is a unitary
composite structural panel;
[0031] FIG. 15 provides calculations for an exemplary calculation
accounting for seismic or wind shear and gravity;
[0032] FIG. 16 provides out-of-plane loading calculations;
[0033] FIG. 17 is a continuation of FIG. 16 and further provides
calculations accounting for eccentricity;
[0034] FIG. 18 provides calculations for various load combinations
and calculations accounting for shear capacity;
[0035] FIG. 19 provides calculations accounting for in-plane
bending and out-of-plane capacity;
[0036] FIG. 20 is a continuation of FIG. 19 and further provides
out-of-plane capacity calculations;
[0037] FIG. 21 provides calculations accounting for buckling of the
compressed shell and gravity load demand including a P-M
interaction diagram;
[0038] FIG. 22 is a continuation of FIG. 21 and further provides
the P-M interaction diagram and also provides calculations
accounting for shear capacity;
[0039] FIG. 23 provides calculations accounting for ladder truss
buckling and concrete shell capacity to transfer shear between
trusses;
[0040] FIG. 24 is a continuation of FIG. 23 and additionally
provides calculations accounting for ladder truss wire
punching-shear capacity; and
[0041] FIG. 25 provides calculations relation to warren truss wire
pullout capacity and limitations on reinforcement ratio.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0042] Referring now to the drawings wherein the showings are for
purposes of illustrating preferred embodiments of the present
invention only, and not for purposes of limiting the same,
[0043] The first step in manufacturing a composite structural panel
according to the present invention is selecting a structural panel
having at least two structural shells, an insulating material
therebetween, and a plurality of truss members extending
therebetween. Preferably, the structural shells 202 and 204 are
fabricated having wire-mesh and it is understood that such shells
are later coated with a shotcrete cement layer 50 as shown in FIG.
1. It is then determined whether the two or more structural shells
202 and 204 act as a unitary composite structural panel as
illustrated in FIG. 7. If after calculations it is determined that
the structural panel 10 is not a unitary composite structural
panel, then parameters are adjusted and calculations are performed
again. Preferably, the parameters adjusted include spacing between
the truss members, number of truss members, thickness of truss
members, thickness of shells, and distance between shells.
[0044] Next, the engineering process continues by calculating the
critical stiffness of the truss members when connected to the rigid
layers to determine if the structural panel is a composite
structural panel. The objective of this step to is determine
whether the individual rigid layers are acting as a composite
section. Using equilibrium equations applied to the system
(including both rigid layers), and principles relating to the
strength of materials, one is able to design a SCIP that conforms
to current design code standards.
[0045] To better illustrate the theory, there are two criteria that
define multiple shell structures being connected through steel
wires are acting as a unitary composite structural panel or
not.
[0046] Referring now to FIGS. 6-7, for Criterion 1, the following
formula controls P.sub.Global>P.sub.Local and for Criterion 2,
the following formula controls V.sub.Truss>V.sub.u.
[0047] For Criterion 1, P.sub.Global is the buckling capacity of
the each shell 202 and 204 in global buckling mode between two
supporting points 200 and 201 as shown in FIG. 6. The support
points are the top and bottom floors for the walls, and the
supporting walls for the slabs. P.sub.Global is calculated based on
the theory of beams of elastic foundation, where the stiffness of
the elastic foundation is equivalent to the truss stiffness that is
restraining the shell in the out of plane direction P.sub.Local is
the buckling capacity of the each shell 202 and 204 in local
buckling mode between neighboring points that connects the trusses
206 to the shells 202 and 204, as shown in FIG. 7.
[0048] Based in the theory of the strength of materials it is easy
to show that if the out of plane stiffness of the trusses 206 is
negligible than P.sub.Global<P.sub.Local. As the out of plane
stiffness of the trusses 206 the global buckling capacity,
P.sub.Global, increases whereas the local buckling capacity,
P.sub.Local, is not affected.
[0049] The panel 10 will behave as comprised of single composite
section when the out of plane stiffness of the trusses 206 reaches
to the points that P.sub.Global>P.sub.Local.
[0050] The critical truss stiffness can be found by setting
P.sub.Global=P.sub.Local for each shell 202 and 204 and solving for
the critical out of plane truss stiffness for each shell. The
critical out of plane stiffness will be the maximum stiffness found
for all shells 202 and 204 that comprise the panel 10.
[0051] More practical approach is to check whether the given
section is a composite section or not. To do so one has to compute
the global buckling capacity, P.sub.Global, and the local buckling
capacity, P.sub.Local, for each shell that comprises the panel and
make sure that for each shell 202 and 204
P.sub.Global>P.sub.Local.
[0052] In Criterion 2, V.sub.Truss is the shear capacity of the
interconnecting trusses 206 between shells 202 and 204, and
V.sub.u, is the shear force applied to the panel 10 due to external
loads.
[0053] In the event that pure bending is present, where the panel
10 has only parallel structural shells and is only exposed to loads
that are inline with the structural shells, then check that the
panel is a unitary composite structural shell. Through this
iterative process, modify the parameters and re-check until the
panel is confirmed as being a unitary composite structural shell
Then, for structural panels having more than two shells, calculate
the stress-strain relationship for each individual structural shell
both in tension and compression. Then, proceed by defining the
ultimate limit states in tension and compression on the
stress-strain relationship for each individual structural shell.
Once it is determined that the shells act as a unitary composite
structural shell, calculate all possible pairs of force and
eccentricity where at least one of the shells exceeds the ultimate
limit state. The limit state surface defining the capacity of the
panel is defined by the possible set of all points that are defined
by limiting force multiplied by the eccentricity defining the
abscissa of the limit surface and the limiting force defining the
ordinate of the limit state surface. This is more particularly
shown in the P-M interaction diagram in FIG. 8.
[0054] If the panel is exposed to transient loading, ie. loading
upon the panel that is not parallel to the shells and/or the shells
are not parallel to each other, then plane shear capacity should
also be checked. It should be assumed in this instance that all
shear is resisted by the trusses that connect the shells, unless it
can be shown otherwise. However, panels 10 that have shells 202 and
204 connected to each other by concrete ribs can be excluded from
this check, such as roof panels that are cantilevered a short
distance and have a concrete rib at an edge thereof connecting the
individual shells of the panel together.
[0055] Shear capacity of the trusses should be calculated based
upon strength of materials and requirements of applicable building
codes.
[0056] Truss connections should also be checked for pullout
capacity and punching shear.
[0057] Referring now to FIG. 1, an exemplary structural panel 10 is
illustrated as made according to the present invention. The panel
10 includes a wire mesh panel 12 on each side of the panel 10 and
when covered in cement, becomes hardened and collectively create
the shells 202 and 204. An insulating material 14, preferably foam,
is provided and sandwiched between the shells 202 and 204. A third
truss system 42 is attached to the panel 10
[0058] Referring now to FIGS. 2-5, first, second, and third truss
systems made according to the present invention are illustrated
which help strengthen the panel 10 and specifically strengthen the
connection between the shells 202 and 204 to create a unitary
composite structural shell. Referring now to FIG. 3 a ladder truss
30 is illustrated designed to be used with a structural panel 10
having a pair of wire-mesh panels 12 connected to and separated by
an insulating material 14 extending therebetween. A pair of
elongated parallel combined truss bars 16 and 18 and a plurality of
elongated ladder bars 20 and 22 extend therebetween in
perpendicular relationship to the combined truss bars 16 and 18 to
form a ladder configuration.
[0059] Referring now to FIG. 2, a third truss system 42 that
combines a warren and ladder truss is illustrated. A pair of
elongated parallel combined truss bars 28 and 29 and a plurality of
ladder bars ladder bars 24 extend therebetween in perpendicular
relationship to the combined truss bars 28 and 29 to form a ladder
configuration. An elongated zigzag bar 40 extends between the
ladder bars 24 and 26. The ladder bars 24 and 26 and the zigzag bar
40 intersect each other at spaced-intervals along the combined
truss bars 28 and 29 and being attachable to a portion of the
structural panel 10 to form a unitary composite structural panel.
Preferably such intersections 32 are equally spaced.
[0060] Referring now to FIG. 4, a first truss system 44 is
illustrated. A ladder truss member 30 is provided that has a pair
of spaced-apart elongated parallel first ladder truss bars and a
plurality of spaced-apart elongated second ladder bars extending
therebetween in perpendicular relationship to the first ladder
truss bars to form a ladder configuration. A warren truss member 46
is provided that has a pair of spaced-apart elongated parallel
first warren truss bars 54 and 56 and a second warren truss bar 58
extending at an angle "a" therebetween in a zigzag configuration.
Preferably, the angle "a" is between 40 and 50 degrees. Even more
preferably, the angle "a" is 45 degrees. The ladder and warren
truss members 30 and 46 are superimposed upon each other and
attachable to a portion of the structural panel 10 such that the
second ladder truss bars 20 intersect the second warren truss bars
58 to form a unitary composite structural panel. Preferably, the
ladder and warren truss members 30 and 46 are superimposed upon
each other along the first ladder truss bars 16 and 18 and the
first warren truss bars 54 and 56 respectively so as to align the
first ladder truss bars 16 and 18 and the first warren truss bars
54 and 56 in parallel relationship.
[0061] Preferably, a plurality of retainer clips (not shown) engage
the first ladder truss bars 16 and 18 and the first warren truss
bars 54 and 58. Such clips may be "C" clips or others which may be
appreciated by one of ordinary skill in the art. Preferably, the
bars 16, 18, 54 and 58 are fabricated from steel.
[0062] Referring now to FIG. 5, a second truss system 52 is
illustrated that is identical to the first truss system 44
described above but adds the additional element of a second warren
truss member 48. In this respect, the ladder truss member 30, the
first warren truss member 46, the second warren truss member 48 are
superimposed upon each other such that the second warren truss
member 48 is inverted and is a mirror-image of the first warrant
truss member 46. This has the advantage of providing further
strengthening to the connection between the shells 202 and 204 when
attached thereto.
[0063] A typical warren truss is that which is manufactured by
DUR-O-WAL.RTM. of Aurora, Ill. Specifically, the DA3100 Truss is
commercially available in several forms including those which
conform to ASTM A82 (uncoated), ASTM A641 (0.10 oz zinc coating),
ASTM A641-Class 1 (0.35 oz zinc coating), ATMA641-Class3 (0.90 oz
zinc coating), and ASTM 163-Class B-2 (1.50 oz zinc coating). These
trusses are available having a rod which is formed in a zigzag
configuration between two parallel rods with an angle of
approximately 30 degrees While it is recognized that other angles,
including 45 degrees, have previously been used for similar types
of trusses, such configurations are typically available from
commercial suppliers as a special-order item that comes at an
additional cost, and was previously considered as an unnecessary
cost that did not appear to yield any particular benefits over
standard warren trusses manufactured having 30 degree angles.
[0064] It has been discovered that manufacturing the warren truss
having an angle in the range of about 40 to 50 degrees provides the
optimum configuration when attached to SCIP panels Such an angle
provides for relatively equal resistance to loads from each
direction.
[0065] As shown in FIG. 5, in a second embodiment of the present
invention, the ladder truss member may be superimposed upon the
first warren truss member and the second warren truss member.
Preferably, the second warren truss member is inverted (flipped)
and is configured having a mirror-image of the first warren truss
member.
[0066] In the typical warren truss configuration, the following
engineering formulas illustrate the design for out-of-plane
loading:
V s = .pi. 3 dlE s D b 4 4 s ( b 2 + 4 d 2 ) 3 2 ##EQU00001##
[0067] In the improved stiffened truss made according to the
present invention that combines a ladder truss member with a warren
truss member,
the following engineering formulas illustrate the design for
out-of-plane loading:
.uparw. | P stud / 2 .dwnarw. | P stud .uparw. | P stud / 2 P stud
= min ( .pi. 3 E s D s 4 16 ( b 2 + 4 d 2 ) , tb f c ' , bt 2 2 s f
c ' ) ##EQU00002##
[0068] In the improved stiffened truss made according to the
present invention that combines a ladder truss with both the first
and second warren trusses, the following engineering formulas
illustrate the design for out-of-plane loading:
V s = l s min [ .pi. 3 E s D s 4 16 ( b 2 + 4 d 2 ) , .pi. D b 2 4
f y sin .alpha. ] ##EQU00003##
[0069] Additional modifications and improvements of the present
invention may also be apparent to those of ordinary skill in the
art. Thus, the particular combination of parts described and
illustrated herein is intended to represent only certain
embodiments of the present invention, and is not intended to serve
as limitations of alternative devices within the spirit and scope
of the invention.
* * * * *