US20080295430A1

US20080295430A1 - Thin shell cementitious coated shear wall structural panel assembly and method of manufacture

Info

Publication number: US20080295430A1
Application number: US12/156,175
Authority: US
Inventors: Michael C. Lewis
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-05-29
Filing date: 2008-05-29
Publication date: 2008-12-04

Abstract

This invention relates to an improved shear wall structural panel assembly that is able to resist gravity loads and lateral forces imposed by wind and earthquake loads. The panel comprises a substantially rectangular frame assembly that is constructed from a plurality of vertical frame members dispensed between and perpendicular to two horizontal frame members. There is a water barrier that is approximately the size of the frame assembly that is fixedly attached to and covering one side of the frame assembly. A reinforcement layer covers and is attached to the water barrier. Four outer frame members are fixedly attached to the perimeter of the frame assembly holding the aforementioned water barrier and reinforcement layer securely in place. A cementitious layer is adjacent to, covering and bonded to said reinforcement layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS:

This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 60/932,283 entitled “Thin Shell Cementitious Coated Shear Wall Structural Panel, Method of Fabrication and Assembly to Create a Structure” filed on May 29, 2007, by the present inventor, Michael C. Lewis, the entire disclosure of which is herein incorporated by reference for all purposes.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention generally relates to structural panel assemblies that are used in residential and other types of building construction. In particular, to improved panel assemblies which are able to resist gravity loads and lateral forces imposed by wind and earthquake loads.

GENERAL BACKGROUND

Interior residential and light commercial wall, roofing, and flooring systems commonly include plywood or oriented strand board (OSB) nailed to a wooden frame or mechanically fastened to a metal frame. OSB consists of pieces of wood glued together and formed into a sheet similar to a sheet of plywood. Other applications use all or a partial steel frame structure.
Regardless of whether the frame of a building is constructed from wood and/or steel, such frame structures are commonly subjected to a variety of forces. Among the most significant of such forces are gravity, wind, and seismic forces. Gravity is a vertically acting force while wind and seismic forces are primarily laterally acting.
One of the primary functions of a shear wall is to dissipate energy from seismic or wind loads while sustaining minimal damage to the shear wall structure. Not all sheathing panels are capable of resisting such forces, nor are they very resilient. Some will fail particularly at points where the panel is fastened to the framing. Where it is necessary to demonstrate shear resistance, the sheathing panels are tested to determine the load which the panel can resist within an allowed deflection without failure.
The walls of a structure fabricated from wood components are commonly formed from a collection of wall studs that are connected to top and bottom members or “plates” at desired spacing schemes (i.e., 16 inches from stud center to center). The studs and plates usually comprise nominal 2 inch by 4 inch and/or 2 inch by 6 inch boards. In metal frame arrangements, the studs and plates commonly comprise C-shaped members that are interconnected, for example, by screws or other fastening techniques.
To provide the frame with resistance to the types of lateral forces mentioned above, shear wall panels are commonly attached to portions of the frame forms by the vertically extending studs and top and bottom plates such that they extend there between. For example, in a wood frame construction, a shear wall panel is commonly formed by the application of one or more types of sheathing such as plywood or oriented strand board (OSB) to the outside or both sides of the wall frame. The sheathing may be fastened to the wall frame at many points, thus creating a shear wall panel. The shear wall panel is used to transfer the lateral forces acting on the frame of the building to the walls of subsequent floors below it and ultimately to the foundation upon which the walls are supported.
Sheathing panels used where a shear rating must be met usually are plywood or OSB. These panels can provide the needed shear strength. Unfortunately, both plywood and OSB are combustible and neither plywood nor OSB is durable when exposed to water. Water intrusion between the panels affixed on either side of the wall flame (hereinafter, the “building envelope”) accounts for the majority of structural defect claims. For example, water intrusion causes deterioration of the structural wood elements (studs and sheathing) within the wall due to soft-rot and decay fungi. Water intrusion also allows mold growth which can be a human health hazard.
Shear rating is a common building industry structural test that follows the guidelines set out in ASTM E72, ASTM E564, and ASTM E2126. Shear rating is based on the testing of two or three identical eight by eight foot assemblies, i.e., panels fastened to framing. One edge is fixed in place while a lateral force is applied to a free end of the assembly until the load is no longer carried and the assembly fails. The measured shear strength will vary, depending upon the thickness of the panel and the size and spacing of the nails or mechanical fasteners used in the assembly. As the thickness of the panel affects its physical and mechanical properties, e.g., weight, load carrying capacity, racking strength and the like, the desired properties also vary according to the thickness of the panel. The measured strength will vary as the nail or mechanical fastener size and spacing is changed, as the ASTM E72, ASTM E564, and ASTM E2126 tests provide. This ultimate strength will be reduced by a safety factor, e.g., typically a factor of two to three, to set the design shear strength for the panel.
In recent years, building construction techniques have experienced a rapid transition from traditional “stick” building to less labor intensive methods. Among these newer developments, “panelization” has emerged as one of the more promising building construction methods. This success is due primarily to two attributes of panelized building systems: 1) opportunity for extensive customization; and 2) substantially reduced construction time as evidenced by erection of a weather tight shell in a week or less. Residential and commercial customers alike continue to find this combination extremely desirable.
Panelized construction provides a way to greatly expedite on-site construction for a building module and may also be particularly beneficial for increasing the speed and efficiency with which a housing addition can be built. Panelized construction allows a considerable amount of the construction to be done in a factory off-site. Off-site construction benefits from mass production, resident expertise, and superior quality control. Panelized construction allows a building module design to be broken down into manageable portions, such as four foot, eight foot, twelve foot, or sixteen foot wide walls, roofs, and floor sections. Because the panels may be substantially flat and of fairly standardized size, it is practical to move large numbers of them over great distances using conventional hauling methods.
Panelized construction also facilitates interchangeability and customization of building module designs. By using standardized wall, ceiling, and floor panels, building module designs may be easily redesigned and customized. Exterior walls may be shifted and interchanged to provide a near infinite variety of designs based on a relatively small selection of panels. Variety of design and customization may be particularly beneficial to housing additions. Different homeowners may have radically varying needs. Some may need additional bedroom space, while others may need additional garage space, a home office, family room, playroom, or utility room.
The efficiency of construction of the housing addition may be further enhanced by providing as much of the construction as is feasible to be pre-installed in the panel. A panel may include a frame which provides the structure of the building module. Additionally, pre-installation of doors, windows, and skylights within the panel frames may substantially decrease on-site building time. Pre-installing insulation and both interior and exterior wall covering layers on the frame may also substantially decrease on-site building time. For example, a sheeting and siding on the exterior surfaces. Another way to improve on-site building times is to provide one or more house systems at least partially built into the pre-fabricated panels. For example, the pre-fabricated panels may be provided with electrical wiring, outlet boxes, and electrically fixture housings, such as lighting and fan fixture housings, pre-installed. Panels may also be pre-installed with other wiring networks, such as cable telephone, audio wiring, security systems, and others. Panels may also be pre-installed with portions of a plumbing, heating, ventilation, or air conditioning systems.
Another way to increase the speed with which a panelized building module may be completed is to provide pre-fabricated panels and building module designs which meet or exceed the residential building codes of jurisdictions in which the building modules may be constructed. While this may not directly increase the actual speed with which the building module is assembled, it may radically decrease the time required to secure permits and inspections. Further, it may prevent costly delays, rebuilds and modifications due to failed inspections. Standardized building codes are frequently adopted with little or no modification in a plurality of jurisdictions. Standardized building codes may facilitate the ability to produce panels and building module designs complying with the building codes in a plurality of jurisdictions. Standardized building codes may include: the Standard Building Code, the BOCA National Building Code, the Uniform Building Code, the Canadian Building Code, the International Building Code, International Residential Code and other such building codes.
A common problem encountered with the pre-fabricated wall systems (such as structurally insulated panels (SIPs)) proposed by the prior art is the difficulty in providing access therein for workmen to install in-wall and through-wall services.
Further difficulty is experienced when considering combinations of different materials such as concrete wall panels with brick and/or brick facing. Such combinations of different construction materials have gained in popularity, where a section of the building being constructed included concrete exterior walls and, in addition, brick faced sections. Providing pre-fabricated building walls which are combination brick facings and concrete panels is esthetically attractive but difficult and expensive to produce. Means to provide such combinations have not as yet been provided except by the used of embossing a brick pattern upon a concrete surface. The resultant product is far from the esthetic appearance obtained when actual brick is employed.

Prior Art

Of the plurality of pre-fabricated building walls provided by the prior art, several of the most pertinent patent applications and issued patents with regard to the present invention are discussed below.
U.S. Pat. Application No. 2007/0175126 filed by Tonyan and Reicherts on Dec. 7, 2006, describes a cementitious shear panel that may be mechanically or adhesively attached to a load bearing frame. Unfortunately, mechanical attachments such as screws or nails create holes in the panel where moisture may intrude. The Tonyan and Reicherts panel also requires cutting of the panels to size, thereby creating waste. Furthermore, adhesive attachment of structural shear panels is not recognized by building codes. FIG. 34 of Tonyan and Reicherts shows ASTM E72 racking test results indicating a low strength system with extremely low ductility. This makes the system undesirable for shear wall use and severely limits the usefulness of the invention.
U.S. Pat. No. 3,693,304 issued to Shell on Jul. 29, 1970, discloses a building panel and wall that uses a heavy gauge steel frame and a thick layer of concrete. This configuration is rarely used for residential or other types of light construction. Shell also leaves a large portion of the steel frame exposed to weathering and subject to oxidation and corrosion. The Shell panels would be much too heavy and expensive to compete with traditional construction currently used for residential or other types of light construction.
U.S. Pat. No. 3,760,540 issued to Latoria et al. on Sep. 8, 1971, describes pre-cast concrete building panels consisting of a steel loading bearing frame with a thick layer of concrete with steel reinforcement within the concrete layer. Use of steel reinforcement generally requires at least one inch of concrete cover over each side of the steel reinforcement to protect it from corrosion. Therefore, the use of steel reinforcement does not lend itself to a thin shell of concrete necessary to minimize weight, cost, and ease of assembly. Moreover, Latoria leaves a large portion of the steel frame exposed and subject to oxidation and corrosion. Similar to Shell, the Latoria panels would be much too heavy and expensive to complete with traditional construction currently used for residential or other types of light construction.
U.S. Pat. No. 4,602,467 issued to Schilger on Jul. 2, 1984, discloses a thin shell concrete wall panel with steel mesh reinforcement. Again, the use of steel reinforcement generally requires at least one inch of concrete cover over each side of the steel reinforcement to protect it from corrosion. In fact, Schilger specifically points out that the concrete shell needs to have thickness of at least 1.5 to 2 inches. The concrete disclosed in the Schilger patent is ordinary concrete that will likely experience sizeable damage during a seismic even due to cracking and spalling of the concrete shell.
U.S. Pat. No. 6,837,013 issued to Foderberg et al. on Oct. 8, 2002, discloses another lightweight precast concrete wall system panel with steel mesh reinforcement. As previously mentioned, the use of steel reinforcement generally requires at least one inch of concrete cover over each side of the steel reinforcement to protect it from corrosion. Similar to Schilger, Foderberg also discloses a thickness preference of 1.5 to 2 inch for their concrete shell. Furthermore, Foderberg discloses a panel that is separate from the load bearing wall and is attached to the load bearing wall by lifting the panel with heavy equipment and attaching it to the load bearing wall with screws. In addition to the likely damage due to cracking and spalling of the described ordinary concrete during a seismic event, the Foderberg wall system panels would be very labor intensive to produce and install, thereby making this wall system cost prohibitive for residential or other light construction projects.
U.S. Pat. No. 7,278,244 issued to Rubio on May 27, 2005, discloses a concrete stud wall system with steel mesh reinforcement. Rubio discloses at least 1.5 to 2 inches of concrete cover over each side of the steel reinforcement to protect it from corrosion. Rubio would likely experience much more damage during a seismic event than the present invention due to cracking and spalling of the ordinary concrete shell.
There is a need for a versatile pre-fabricated wall system that is relatively low cost for facile insallation and production; light weight yet structurally strong enough to be used as basement walls, foundations, floors and roofs; easily combined and assembled to other desirable finish materials, such as brick or stone, to enhance the aesthetics of the wall system; offers excellent thermal-resistive and weather-resistive characteristics; and, is capable of multi-level incorporation in a building structure.

OBJECTS AND ADVANTAGES OF THE PRESENT INVENTION

It is one object of the shear wall structural panel component of the present invention to replace the plywood or oriented strand board (OSB) and the siding with one shear wall panel component that is the structural shear panel and the exterior siding. This will reduce the number of assembly components thereby reducing construction time and cost.
Another object of the present invention is to make panels larger than the prior art shear walls thereby speeding construction and reducing the number of seams that occur between pieces of exterior siding. Minimizing the seams minimizes potential moisture penetration and subsequent moisture damage.
Another object of the present invention is to use a high performance ductile concrete for the outer shell and a non-metallic, thinner reinforcement layer thereby allowing the required thickness of the outer cementitious shell to be considerably thinner than the prior art so called ‘thin shell’ panels. By combining a wood flame with a true thin shell, the structure dead load is reduced allowing for a relatively light and open structure.
It is another object of the present invention is to provide a shear wall that has improved shear load capacity and stiffness.
It is yet another object of the present invention to provide a shear wall exhibiting improved energy absorption and ductility that will experience much less damage under loading compared to other shear wall systems.
Another object of the present invention is to provide a shear wall structural panel that may be used an alternative to costly masonry construction.
It is yet another object of the present invention to provide a shear wall that has a vastly superior building envelope that is unaffected by moisture intrusion and provides a means of escape to water that does intrude; is resistant to mold and decay fungi, thus reducing structural defect claims; is resistant to insect attack by termites and carpenter ants and intrusion of pests such as mice; is fire resistant; and is much more durable than wood or normal concrete, all of which ultimately reduces maintenance costs.

SUMMARY OF THE INVENTION

The present invention is an improved shear wall structural panel assembly that resists gravity loads and lateral forces imposed by wind and earthquake loads. The shear wall structural panel comprises a substantially rectangular frame assembly that is constructed from a plurality of vertical frame members dispensed between and perpendicular to two horizontal frame members. A water barrier that is approximately the size of the frame assembly is fixedly attached to and covering one side of the frame assembly. A reinforcement layer covers and is attached to the water barrier. Four outer frame members are fixedly attached to the perimeter of the frame assembly holding the aforementioned water barrier and reinforcement layer securely in place. A cementitious layer is adjacent to, covering and bonded to the reinforcement layer.
The shear wall structural panel assembly of the present invention is a combined load bearing and shear wall that also provides exterior siding.

BRIEF DESCRIPTION OF THE DRAWINGS

The above description and other objects, advantages, and features of the present invention will be more fully understood and appreciated by reference to the specification and accompanying drawings, wherein:

FIG. 1 is an exploded view of a shear wall structural panel depicting the primary layers of the panel wall of the present invention.

FIG. 2 is a front elevation view of the frame assembly of the present invention.

FIG. 3 is a cross-sectional view at line 3-3 of FIG. 2.

FIG. 4 is a perspective view of one embodiment of an assembled shear wall structural panel assembly of the present invention.

FIG. 5 is a sectional view of the lower left corner of the assembled shear wall panel of FIG. 4 detailing the layers and components of the present invention.

FIG. 6A is a cross-sectional side view at line 6-6 of FIG. 4.

FIG. 6B is an enlarged view of the FIG. 6A further detailing the components of the assembly.

FIG. 7 is a front view of the lower right corner of the shear wall structural panel assembly of the present invention illustrating the placement of weep openings and flashing used in one embodiment of the present invention.

DRAWINGS

REFERENCE NUMERALS

100 Initial Frame Assembly
120 Water Barrier
130 Thin Shell Cementitious Panel (TSCP)
140 Reinforcement Layer
200 Frame Assembly
202 Corner Brackets
204 Outer Frame Member
208 Vertical Frame Member
220 Horizontal Frame Member
400 Shear Wall Structural Panel Assembly
402 Fasteners
502 TSCP Step
602 Flashing
604 Flashing Attach Tab
606 Tab Fastener
610 Weep Opening
702 Initial Frame Fastener

DETAILED DISCUSSION OF THE EMBODIMENTS

Referring to the figures, like elements retain their indicators throughout the several views.
FIG. 1 is an exploded view of a shear wall structural panel assembly depicting the primary components of the shear wall structural panel assembly of the present invention. Initial Frame Assembly 100, in this embodiment, comprises several nominal two inch by six inch by eight foot wood studs. The studs are fastened to one another for strength and stability by nails, screws, or other fastening means (not shown) as is common in the building trade.
In this embodiment, Water Barrier 120 is placed over Initial Frame Assembly 100 and attached to the outer surfaces of Initial Frame Assembly 100 using staples (not shown). Water Barrier 120 in this embodiment is plastic sheeting that is commonly used in the building trade to prevent moisture from contacting the wood structure. One example of which is Dupont's Tyvek™ which is a high-density polyethylene (HDPE), although there are other suitable products as well.
It has also been contemplated to use multiple layers of Water Barrier 120 when needed for added moisture control.
Reinforcement Layer 140 is stretched over Initial Wall Frame Assembly 100 on top of Water Barrier 120. Reinforcement Layer 140 is attached in several places along each of the stud components of Initial Wall Frame 100 as well as around the perimeter by fastening means such as staples, nails or tacks (not shown). Reinforcement Layer 140 may be metal sheet, wire mesh, polymer grid, polymer fabric or other suitable material. Some examples of available products for Reinforcement Layer 140 are Mirafi BasXGrid 11 or Mirafi HP370. In some applications, Reinforcement Layer 140 may be eliminated from the design where wall strength is sufficient without it.
In another embodiment, each Vertical Frame Member 208 has wooden lath attached along its full length. The wooden lath creates a friction joint that holds the reinforcement securely to the frame and acts to make the TSCP 130 composite with Initial Frame Assembly 100.
The outer edges of Water Barrier 120 are lifted upward over the top of Reinforcement Layer 140 and Outer Frame Members 204 are attached around the perimeter of Initial Frame Assembly 100 thereby further securing Reinforcement Layer 104 and Water Barrier 120. Reinforcement Layer 104 is now disposed between two layers of Water Barrier 120. Corner Brackets 202 are now attached using fastening means (not shown) such as screws, nails or the like. Water Barrier 120 is now wrapped over the top and down the perimeter of the now attached Outer Frame Members 204. Water Barrier 120 is attached using fastening means (not shown) such as staples, nails, tacks or the like.
Thin Shell Cementitious Panel 130 (hereinafter “TSCP 130”) is a layer of concrete that is cast against Reinforcement Layer 140. The term “cementitious” includes but is not limited to concretes and mixtures thereof, and other building compositions which rely on hydraulic during mechanisms. Suitable cements, such as lime cement, Portland cement, refractory dement, slag cement, expanding cement, pozzolanic cement, mixtures of cements, etc. may be used according to needed size and associated strength.
In one embodiment, Engineered Cementitious Composite 28 (hereinafter “ECC 28”) concrete is used for TSCP 130. ECC 28 is a unique cementitious material that exhibits strain hardening and steady state flat cracking behavior in tension and flexure. Steady state flat cracking behavior occurs when each crack that initiates in the concrete matrix maintains a uniform and very small width along the entire length of the crack. This allows the fibers in the concrete to continue transferring load, or dissipating energy, across the crack. ECC 28 can be ductile to approximately 2% or more tensile strain.
The main energy dissipation modes for the present invention are fundamentally different from prior art wood sheathed walls. The thin shell cementitious panel wall of the present invention dissipates energy through tensile strain hardening of the ECC 28 and/or plastic deformation of Reinforcement Layer 140. Prior art wood shear walls generally dissipate energy through inelastic fastener deformation, friction of components and crushing of the wood. This leads to extensive damage and high cost of repair in the prior art shear walls.
To create TSCP 130 as shown in FIG. 1, ECC 28 concrete or the like is cast into a mold in a thin layer that is placed horizontally on a level surface. With TSCP 130 in an unset or soft state, Initial Frame Assembly 100 and Outer Fame Members 204 with Water Barrier 120 and Reinforcement Layer 140 attached thereto is placed on top of TSCP 130 with Reinforcement Layer 140 facing downward and thereby protruding into TSCP 130. TSCP 130 encapsulates most of Reinforcement Layer 140. The assembly is held in the proper position relative to TSCP 130 by small fixtures at several locations (not shown). This type of ‘face down’ concrete wall casting is well known to those skilled in the art. Further details of the assembly process are forthcoming in the latter figure discussions.
Additionally, it has been contemplated to cast TSCP 130 in a ‘face up’ configuration with the concrete being poured onto the attached Reinforcement Layer 140. To accomplish pouring the concrete onto Reinforcement Layer 140, Outer Frame Members 204 would act as a screed for setting the level of the concrete used for TSCP 130. Before TSCP 130 is fully set, in this embodiment, Outer Frame Members 204 are covered with set or unset concrete creating a TSCP step similar to TSCP Step 502 that will discussed in FIG. 5.
It has also been contemplated to eliminate Water Barrier 120 if Reinforcement Layer 140 and/or TSCP 130 provide an adequate water or moisture barrier.
In another embodiment, it has been contemplated to spray the concrete used to create TSCP 130 onto a vertical wall that is already assembled into the shell of a structure.
FIG. 2 is a front elevation view of Frame Assembly 200 of the present invention. As previously discussed in FIG. 1, Initial Frame Assembly 100, comprises several nominal two inch by six inch by eight foot wooden studs. The studs are fastened to one another for strength and stability by nails, screws, or other fastening means (not shown) as is common in the building trade. The overall size of the shear wall structural panel of the present invention is determined by the size of Frame Assembly. FIG. 2 depicts Frame Assembly 200 as an eight foot square. However, depending upon the application, Frame Assembly 200 can easily be made in various widths and heights. For example, four by eight feet, eight by eight feet (as shown), ten by eight feet, or twelve by eight feet.
Vertical Frame Members 208 are spaced substantially equidistance apart and extend between and fastened to Horizontal Frame Members 220. As discussed in FIG. 1, Water Barrier 120 (not shown) and Reinforcement Layer 140 (not shown) are disposed atop Initial Frame Assembly 100 but are not shown for clarity of placement of Outer Frame Members 204 which are attached slightly above Initial Frame Assembly 100. The placement of Outer Frame Members 204 is discussed in detail with the cross-sectional view shown in FIG. 3.
For added security and shear strength, Corner Brackets 202 are attached prior to the final attachment of Water Barrier 120 to the perimeter of Outer Frame Members 204. This provides some protection from moisture and the environment to Corner Brackets 202 as well.
In this embodiment, Corner Brackets 202 are 18 gauge thick sheet metal, approximately twenty inches long by approximately three inches wide and bent into an essentially 90 degree angle. Corner Brackets 202 can be of various sizes and materials according to strength needs and wall size. It has also been contemplated to eliminate Corner Brackets 202 in applications where the wall strength is adequate without them.
FIG. 3 is a cross-sectional view of Frame Assembly 200 at line 3-3 of FIG. 2 depicting the relative placement of Initial Frame Assembly 100 with Outer Frame Members 204. As depicted in FIG. 3, Outer Frame Members 204 are attached an offset distance ‘d’ above Initial Frame Assembly 100. The distance ‘d’ is approximately the thickness of TSCP 130 which in this embodiment is approximately one half inch thick. This offset provides additional strength to the assembly by allowing TSCP 130 to transfer loads to Outer Frame Members 204.
In this embodiment, the previously discussed mold for face down casting would have a slight recess, approximately the depth of distance ‘d’, around the perimeter to accommodate Outer Frame Members 204 with a coating of TSCP 130 as well as creating a step in the TSCP 130 layer. TSCP Step 502 covers and protects Outer Frame Members 204 from weathering. TSCP Step 502 also allows an approximately one-half inch thick concrete shell over the interior portion of the wall, rather than one inch thick across the entire panel width. A thick shell wastes material and is not needed structurally. TSCP Step 502 also provides an aesthetically pleasing border to TSCP 130.
It has also been contemplated to set decorative elements such as thin brick panels into the exterior surface of TSCP 130. Further, the exterior surface of TSCP 130 may be textured, patterned, or sculpted to look like natural stone, brick, or the like. Texturing or patterning can be created by sculpting the surface of the mold used for forming TSCP 130. Additionally, coloring pigment may be added during the mixing of TSCP 130 to minimize or eliminate the need for painting.
FIG. 4 is a perspective view of one embodiment of an assembled shear wall structural panel of the present invention. As previously discussed, Corner Brackets 202 are affixed to the upper corners. Although in this embodiment Corner Brackets 202 are shown affixed exterior to Water Barrier 120, this is primarily for clarity of placement as Corner Brackets 202 are preferably affixed interior to Water Barrier 120 to protect them from the environment. Fasteners 402 are shown along the perimeter of Shear Wall Structural Panel Assembly 400. In this embodiment, Fasteners 402 are nails of a length that extend through Water Barrier 120, through Outer Frame Members 204, through Reinforcement Layer 140 sandwiched between two layers of Water Barrier 120, and into Initial Frame Assembly 100.
Reinforcement Layer 140 and TSCP 130 work together to create a very stiff, yet ductile, panel under lateral loading conditions. This is accomplished by carefully selecting Reinforcement Layer 140 with tensile strain characteristics that complement those of the TSCP 130 and using optimum pre-stress force in dispensing or laying out Reinforcement Layer 140. The pre-stressed Reinforcement Layer 140 is also intended to reduce the initial slippage of the shear wall components at the onset of loading. Reinforcement Layer 140 also holds the framing members together during loading. Pore size of Reinforcement Layer 140 has a direct effect on the strength of the bond between TSCP 130 and Reinforcement Layer 140.
During lateral loading of traditional wood frame walls, the interior gypsum wallboard components are damaged. This damage is due to gypsum wallboard having a higher stiffness than the wood shear panels. The higher stiffness attracts the load and damages the wallboard. One of the benefits of the Shear Wall Structural Panel Assembly of the present invention is that the cementitious layer, ECC 28 in one embodiment, has a higher stiffness than gypsum wallboard. This allows the gypsum panels to sustain comparatively less damage during lateral loading as the ECC 28 panels will attract the load rather than the gypsum. This could be a significant cost savings associated with protecting the interior gypsum wallboard.
Completed Shear Wall Structural Panel Assembly 400 is joined to other similar completed assemblies along with floor and roof diaphragms. Using appropriate fasteners and sealants, the complete structural shell of a building is produced.
This fabrication method can be conducted in a controlled indoor environment, such as a factory. The completed panel assemblies would be shipped to the building site and set in place using a small crane or other suitable methods. It has also been contemplated to fabricate the panel assemblies at the building site or at any other suitable location.
When used in residential, light, and other suitable types of construction, the Shear Wall Structural Panel Assembly 400 of the present invention provides superior performance as a lateral force resisting system.
FIG. 5 is a sectional view of the lower left corner of Shear Wall Structural Panel Assembly 400 of FIG. 4. As shown, Water Barrier 120 is laid over the top and one side of Horizontal Frame Members 220 and outermost Vertical Frame Members 208—both subcomponents of Initial Frame Assembly 100. Reinforcement Layer 140 is disposed over Water Barrier 120 and attached to all Vertical Frame Members 208, Horizontal Frame Members 220 as well as the perimeter of Initial Frame Assembly 100 with attachment means (not shown) such as staples, nails, tacks or the like. In this embodiment, Water Barrier 120 is then brought up, over Reinforcement Layer 140 and Outer Frame Members 204 are attached to the outermost Horizontal Frame Members 220 and outermost Vertical Frame Members 208. The remaining Water Barrier 120 is wrapped over Outer Frame Members 204 and fastened in place with small staples (not shown). Fasteners 402 (not shown) extend through and secure all other layers.
In the FIG. 5 embodiment, TSCP Step 502 is shown around the perimeter of the TSCP 130 layer. As discussed in FIG. 3, TSCP Step 502 will be approximately a height similar to distance ‘d’ that is created by Outer Frame Members 204 being attached slightly higher than Initial Frame Assembly 100.
FIG. 6A is a cross-sectional side view of Shear Wall Structural Panel Assembly 400 at line 6-6 of FIG. 4 further detailing the interior or envelope of the panel assembly. Since TSCP 130 is impervious to water, it is important to have a means of allowing moisture that may get into the envelope due to interior or exterior moisture sources to escape from the panel envelope.
As shown in FIG. 6A, Flashing 602 extends between Vertical Frame Members 208 and attaches to the inside of Vertical Frame Members 208 at Flashing Attach Tabs 604 with Tab Fasteners 606. Tab Fasteners 606 are small tacks, nails, or staples that extend through Flashing Attach Tabs 604. Flashing 602 is angled toward TSCP 130 at the base of the panel envelope to divert any moisture away from Initial Frame Assembly 100.
FIG. 6B is an enlarged view of FIG. 6A further detailing the components in the panel envelope of Shear Wall Structural Panel Assembly 400. Weep Opening 610 is shown in phantom extending through TSCP 130. Weep Opening 610 allows any moisture that may get into the panel envelope of Shear Wall Structural Panel Assembly 400 to escape to the outside.
FIG. 7 is a front view of the lower right corner of Shear Wall Structural Panel Assembly 400 of the present invention. Weep Openings 610 are shown at the base of the panel envelope. In this embodiment, Weep Openings 610 are approximately 0.125″ in diameter with one or two Weep Openings 610 disposed between Vertical Frame Members 208 just above the lower Horizontal Frame Member 220 thereby allowing any moisture in the panel envelope to be expelled.
Wherein the terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

Claims

1. A shear wall structural panel assembly for resisting gravity and shear loads, comprising:

a substantially rectangular frame assembly having a plurality of parallel vertical frame members dispensed between and perpendicular to two horizontal frame members, said frame assembly having an outer perimeter, a first side and a second side opposite said first side;

a water barrier approximate the size of said frame assembly fixedly attached to and covering said first side of said frame assembly;

a reinforcement layer approximate the size of said frame assembly fixedly attached to said frame assembly and covering said water barrier; and

an outer frame assembly fixedly attached to said outer perimeter of said frame assembly; and

a cementitious layer disposed on, covering and bonding to said reinforcement layer;

wherein, the shear wall structural panel assembly is a combined load bearing wall, shear wall, and exterior siding.

2. The shear wall structural panel assembly of claim 1, wherein said vertical frame members and said horizontal frame members are nominal two inch by six inch wood studs.

3. The shear wall structural panel assembly of claim 1, wherein said water barrier is breathable plastic sheeting.

4. The shear wall structural panel assembly of claim 1, wherein said reinforcement layer is a polymer mesh.

5. The shear wall structural panel assembly of claim 1, wherein said outer frame assembly is a plurality of nominal two inch by four inch wood studs.

6. The shear wall structural panel assembly of claim 1, wherein said cementitious layer is concrete comprising, on a dry basis, 45 to 75 weight percent cementitious power, 10 to 30 weight percent sand, 1 to 5 weight percent polyvinyl alcohol fibers, and 0.5 to 2.0 weight percent chemical admixture, said continuous phase being reinforced with polyvinyl alcohol fibers.

7. The shear wall structural panel assembly of claim 1, further comprising at least two corner reinforcement brackets fixedly attached to at least two exterior corners of said outer flame assembly.

8. The shear wall structural panel assembly of claim 1, wherein each of said vertical flame members has a wood lath fixedly attached to and extending the length of said vertical flame members, wherein said wood lath secures said reinforcement layer to said frame assembly prior to application of said cementitious layer.

9. The shear wall structural panel assembly of claim 1, wherein said cementitious layer is sprayed onto and bonded to said reinforcement layer with said the shear wall structural panel assembly vertically oriented.

10. The shear wall structural panel assembly of claim 1, further comprising at least one weep opening extending through said cementitious layer, through said reinforcement layer and through said water barrier, wherein moisture inside the panel is allowed to escape.

11. The shear wall structural panel assembly of claim 10, further comprising a portion of flashing spanning between and perpendicular to each of said vertical frame members, said flashing extends downward from said second side of said frame assembly to said first side of said frame assembly and below said weep openings.

12. The shear wall structural panel assembly of claim 1, wherein said outer frame assembly is extended a distance above said first side of said frame assembly creating a frame step, said cementitious layer is dispensed on said reinforcement layer and said outer frame assembly creating a cementitious step having a height of said distance, wherein, said frame step provides added strength to the shear wall structural panel assembly.

13. The shear wall structural panel assembly of claim 1, wherein said cementitious layer further comprises a colorant eliminating the need for exterior painting.

14. The shear wall structural panel assembly of claim 1, wherein said cementitious layer 15 further comprises an exterior having aesthetic surface features.

15. The shear wall structural panel assembly of claim 12, wherein said features are embedded stone veneer.

16. The shear wall structural panel assembly of claim 12, wherein said features are embedded brick veneer.

17. A method of manufacturing a shear wall structural panel assembly, comprising the steps of:

providing a first frame structure having a plurality of parallel vertical frame members dispensed between and perpendicular to two horizontal frame members, said frame assembly having an outer perimeter, and a first side;

attaching a water barrier approximate the size of said frame assembly covering said first side of said frame assembly;

attaching a reinforcement layer approximate the size of said frame assembly to said frame assembly and covering said water barrier;

attaching an outer frame assembly to said outer perimeter of said frame assembly creating a structural assembly having an assembly perimeter;

providing a mold having an outer dimension approximate that of said assembly perimeter;

dispensing a cementitious material to a depth in said mold;

placing said structural assembly with said first side down onto said cementitious material in said mold, said cementitious layer bonding to said reinforcement layer;

wherein, the shear wall structural panel assembly is a load bearing wall, shear wall, and exterior siding.

18. The method of claim 17, wherein said outer frame assembly is extended a distance above said first side of said frame assembly creating a frame step, said cementitious layer is dispensed on said reinforcement layer and said outer frame assembly creating a cementitious step having a height of said distance, wherein, said frame step provides added strength to the shear wall structural panel assembly.

19. The method of claim 17, further comprising the step of attaching at least two corner reinforcement brackets to at least two exterior corners of said outer frame assembly.

20. The shear wall structural panel assembly of claim 1, wherein said outer frame assembly, said vertical frame members, and said horizontal frame member of said frame assembly and are light gauge steel.