Patent Grant
10533339
The present invention generally relates to structures such as buildings, load bearing shapes or components thereof. More specifically the invention relates to in situ fabrication of one or more load bearing shapes utilizing minimally supported tensile load bearing net combined with compressive load bearing hardening or fixing material that is separated by a non-linear reinforcing bar that provides depth of member for the assembly.
Description of Related Art including information disclosed under 37 CFR 1.97 and 1.98—Construction methods for conventional housing and commercial buildings often employ wood framed walls covered by external sheathing and an outer finish layer of masonry, stucco, wood siding, shingles, or the like. These methods and structures are costly and time-consuming.
High and rising construction costs contribute to economic inflation. High and increasing rents contribute to a reduced standard of living for many people. High construction prices exclude many people from home ownership. High rents for office space contribute to the failure of small business.
U.S. Pat. No. 5,566,521 provides a strong and durable structure and method for constructing buildings. However, still more rapid building systems are desirable.
It would be desirable to produce buildings of all descriptions by new methods that enable rapid erection at lower cost than conventional methods.
Further, it would be desirable to fabricate building structures in situ, using locally available materials that may be wastes or recycled materials of potentially very low cost.
In addition, it would be desirable to have available a method of building structures that is changeable on site, by merely altering the shape or placement of a fabric that is minimally supported.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the method and structure of this invention may comprise the following.
An embodiment relates to a load bearing structure including a first fixed net layer, a second fixed net layer and a non-linear structure in between. The first fixed net layer may include a first layer of flexible, drapable fabric and a fixing material that fixes the shape of the first layer of flexible, drapable fabric. The second fixed net layer may include a second layer of flexible, drapable fabric and a fixing material that fixes the shape of the second layer of flexible, drapable fabric. The non-linear reinforcing structure may be in communication with the first and second fixed net layers and may be configured to share with the first and second fixed net layers a load applied to the load bearing structure.
An embodiment provides a building structure and method for constructing a building in a substantially shorter time than typical by prior, conventional methods, using low cost, readily available materials, especially indigenous materials.
Another embodiment provides a structure and method of construction that replaces traditional or conventional internal post and beam structural configuration with a more economically attractive alternative. In particular, the alternative construction provides an exoskeleton or external structural element. Exoskeleton construction is the most efficient type of construction. The alternative construction may include a post and beam, an exoskeleton skin without post and beam, or both.
Another embodiment enables the use of indigenous materials when and where practical, both for convenience and cost savings.
Another embodiment provides a method of constructing a building that allows one of the structural parts of an exoskeleton to be fabricated on-site and first utilized as a mold, second utilized as one or more of two structural skins, and third utilized as a finished coating.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with the description, serve to explain the principles of the invention. In the drawings:
The various embodiments described below relate to building structures and methods for constructing a structurally sound building potentially in a reduced time and potentially at a reduced cost as compared to prior conventional practices. The building structure is constructed as an exoskeleton. For purposes of defining such a building structure, an exoskeleton employs three features: an inner structural skin or shell, an outer structural skin or shell, and an intermediate filler layer having the function of spacing apart the inner and outer shells in order to increase depth of member or moment of inertia. The invention refers to a building structure, which encompasses all parts of a building, such as roof, floor, walls, and finish coatings. Components such as wall or roof will be described individually in order to disclose preferred structure, but the teachings of any component are applicable to all other components and entire building structures. The method and resulting structure are best understood by reference to the drawings.
Prior methods of construction in which a fixative was applied to a flexible fabric required a mold or formwork to support liquid or plastic hardening materials. This limitation is costly in both materials and labor. In the previous patent (U.S. Pat. No. 8,104,233) from which this application claims priority, the first fixed layer does not require a supplementary or auxiliary mold. Only minimal support is used depending on the desired configuration. As will be discussed in more detail below, the instant application provides instructions to further minimize and even eliminate the need for supports.
Prior methods that use fixed nets disclose that layers of hardened fabrics or nets are stacked, or layered, one upon another. The shapes of the additional stacked layers are substantially dictated and defined by the original mold layer shape. Thus, the layers must be substantially identical to one another and in full contact with one another. In contrast, as disclosed in U.S. Pat. No. 8,104,233 and discussed in more detail below, there are many different efficient load bearing shapes. As one example, a folded plate comprising a fixed tensile net may be utilized as a spacer between fixed layers to provide depth of beam or member between the exterior surface layers. However, the inventor has discovered a more effective way of producing these advantageous shapes where a tensile load bearing fabric material is not necessary in the intermediate core area to separate one exterior layer from the other. Instead, the more efficient non-linear spacing bar is used to replace the tensile load bearing net or expanded materials.
The net fiber materials are chosen to bear tensile loads applied to the fixed layer(s). Further, the hardening or fixing materials are chosen to bear compressive loads applied to the fixed layer(s). However, net fiber materials and hardening or fixing materials that support both tensile and compressive loads may be chosen. Within the context of this application, the words self-supporting, load bearing, structural, and reinforcement relate to the capacity to resist loads applied pursuant to structural engineering principles and protocols. Further terminologies used herein are defined by those skilled in the art of structural engineering. Specifically, such terms as depth of beam or member, moment of inertia and other words of art apply to the shapes and the spaces, or air, defined by the combination of the non-linear reinforcing bar in assembly with the outer exterior coatings. The term in-situ means monolithically formed in place, such as cast in place, and assembled in place, i.e. on site. In-situ includes forming in the position of ultimate use, such as forming the wall of a building. In-situ also includes forming on-site but not in the ultimate position, such as forming a roof portion adjacent to the building which is later put in place on the building.
According to the invention, a building shell or envelope is formed of a net layer that is carried by any necessary supports. A hardening layer is applied to fix the shape of the net layer and to establish wall, roof, and floor sections, which if desired are formulated to be of sufficient strength to be a finished assembly. If required, especially to accommodate changes of plan, the hardened net may serve as an in situ mold for receiving application of further layers. Building sections can be generally flat or can be arranged in shapes selected from parallel-sided segments and converging-sided segments, with troughed or domed section shapes, and combinations of these. A building structure can be formed of shell sides and central spacer or filler layer. Optionally, posts or beams support the walls, roof, and floor sections and can be formed integrally of net and hardener layers.
The structure of the building shell provides a first self-supporting component layer that is structurally adapted to bear both tensile and compressive loading applied. The first layer is formed of fabric treated with fixable material. A second self-supporting component layer is spaced from said first component layer by an intermediate layer. The second layer is structurally adapted to bear both tensile and compressive loading and is formed of a tensile element treated with fixable material. The intermediate component layer occupies the space between the first and second component layers and establishes an exoskeleton structure.
The tensile element of the second layer can be a structural post. The fixable material covers the structural post, integrating the post into the second component layer.
Alternatively, the tensile element of the second layer can be a layer of fabric. In this variation, the second component layer also may include a structural post that is covered or wrapped by the layer or fabric. Both the post and fabric are treated with the fixable material to establish an integrated structure.
Similarly, the first component layer may include a first structural post that is covered by the fixable material; and the second component layer may include a second structural post that is fixed in the second component layer by a covering layer of fabric treated with the fixable material. The first and second structural posts can be arranged in either offset alternating positions or in opposite juxtaposed positions.
In another variation, the first component layer includes a first structural post that is fixed in the first component layer by a covering layer of the fabric treated with fixable material. The second component layer is attached to the first structural post at a side opposite from the first component layer, such that the first structural post establishes the thickness of the space between the first and second component layers.
According to a method of forming a building structure, first a framework or support is erected, suited for carrying a layer of fabric in the general shape of the intended building or any of its components. Next, the layer of fabric is applied over the framework to define the building or a building component. Then, the fabric layer is treated with a fixable material that combines with the fabric to form a self-supporting shell structure of the building or building component. The shell is self-supporting exclusive of the framework, which then becomes an optional structure. Thus, optionally the framework is removed after the self-supporting shell has been established. Removing the framework allows the reuse of its components and is especially useful where the framework components are in short supply or the components are a nonrenewable or scarce resource.
The fixable material is a hardener or coating that may penetrate into the fabric layer before or as it hardens, forming a first self-supporting shell. The fabric and fixable material form a hard shell that is sufficiently self-supporting that subsequently it can serve as a mold for application of further layers. That is, when first layer of fabric is fixed, the result is a first self-supporting shell that can serve as a mold for further layers without the use of additional molds or fixtures. Thus, it is possible to apply a second layer of fabric over the first self-supporting shell. The second fabric layer then can be treated with a fixable material to establish a second layer of shell. The second layer and the fixative are fully supported by the first fixed layer. That is, even with the addition of the weight of the second layer of fabric and the second fixative, additional molds and fixtures are not required. Multiple layers of shell may be formed in series to achieve a desired strength. Also, the ability to form multiple layers without employing a mold other than the original layer allows the strength of a building or of any selected building component to be increased or adjusted in the field. This field adjustment requires no waiting for availability and delivery of additional structural components such as larger trusses, as would be required in conventional building practice.
The building method contemplates that an exoskeleton structure will be desirable for most building structures. In order to achieve an exoskeleton structure, an intermediate spacer layer is applied—to the first self-supporting shell. Then a second layer of fabric is applied—contiguous to or attached to the intermediate layer. The second fabric layer is treated with fixable material to establish a second layer of shell structure over the intermediate layer, thereby creating in situ the exoskeleton structure. Thus, the ability to mold one layer to another allows the efficient formation of an exoskeleton having opposite structural skins separated by an intermediate layer of selected and variable thickness.
Recognizing that a fabric or net layer might be difficult to work with in high winds or due to other ambient difficulties, it is possible to overcome such a problem by pretreating the fabric to stiffen it. After the fabric has been applied to a framework or mold surface, it may be treated by applying a thin, fast acting surface coat of hardening agent or penetrating agent that stiffens fibers of the fabric layer.
In certain structures and building types, it may be desirable to modify the characteristics of an exoskeleton or shell by the addition of structural members such as posts or beams. This modification can be implemented by forming the first self-supporting shell and then applying structural supporting members to the shell. In a specific application of this concept, a roof section can be fabricated by erecting a framework of at least two upper roof supports in an at least partially spaced apart orientation. The fabric layer is applied to this framework and treated with fixing agent. If the fabric layer is applied in tension between the supports, the result is a flat roof section. If the fabric layer is applied in loose or draped configuration between the supports, the result is a troughed or catenary curved roof section. The step of applying the fixing layer to the fabric both hardens the fabric into a shell and may incorporate the roof supports into the shell.
In a variation of the method, the upper roof supports are supported at a preselected level, and the troughed portion of the draped fabric extends below the preselected level. Then, before fixing agent is applied, a lower roof support is applied to the troughed portion of the fabric below the preselected level. The lower roof support tensions the fabric between upper and lower roof supports, establishing a shell having a folded plate structure. Both upper and lower supports can be incorporated into the shell.
In another variation of roof structure, a fabric layer is draped between roof supports in troughed configuration. Treating the fabric with fixable material establishes a self-supporting, troughed roof shell structure. The troughed roof shell structure is inverted to form a vaulted roof structure.
In
In this context, “frozen” refers to establishment of a permanent or fixed shape and does not necessarily require or imply the use of cold temperatures. The treating or coating will be referred to as a fixable material or fixing agent, which indicates that the material itself or the material in combination with the net layer in due course forms a structure that is self-supporting, for example by the fixable agent hardening or drying. This definition accommodates a possible cure time, drying time, or the like, if any, in order for the fixed or permanent shape to be achieved.
For purposes of this invention, preferred netting materials include rock fibers, particularly basalt fibers, to form structural nets or scrims. These preferred choices perform particularly well as compared to known construction netting, scrim, cloths, and lathe. However, known scrims of various other materials can be used. Known materials include plastics, polymers, other synthetics, fiberglass, metals, and alloys. Polymers can have a reinforced core or may be of the type referred to as fiber reinforced polymers. Examples of fibers added to a polymer are glass, carbon, polypropylene, and like materials. Examples of synthetics include high-density polyethylene, low-density polyethylene, nylon, polypropylene, and like materials. Examples of metals and alloys of metals include steel and aluminum.
The use of basalt fiber in netting and in other elements of the building structure produces improved performance and environmental advantage. This type of fiber is produced from a substantially unlimited resource, as basalt or similar rock that composes roughly 90% of the earth's crust. Basalt fibers previously have lacked sufficient grip to function properly in concrete mix designs or as a scrim for receiving a concrete coating. As used here, the term ‘grip’ refers to the ability of a deformed reinforcing bar to resist any movement or slippage when encased with concrete.
Basalt filaments or fibers are produced by heating basalt to a melting or plastic temperature, and the molten material is then extruded through bushings. In further processing at a forehearth, the filaments are next combined or woven into the final product and sized, typically by addition of a plastic or polymer coating. Final products might be a strand useful in forming netting or fabric, or strands can be combined to form a reinforcing bar similar to steel rebar.
In order to create a fiber with improved grip, the basalt material can be deformed while being processed from hard rock, to molten rock, to malleable rock, and back to cooled hard filament. The deformations 82,
Alternate method of increasing grip may be utilized. Filaments can be deformed, such as by kinking, bending, or forming into loops as illustrated in
Used as netting, rebar, or chopped fiber, the improved basalt fibers or filaments are significantly stronger than other commonly used reinforcements. Basalt fibers are almost ten times stronger than grade forty steel reinforcement. Compared to the cost of producing steel rebar, production savings are almost thirty percent. Compared to the cost of producing carbon fiber, basalt fiber costs about one tenth as much; with the added benefit that basalt fiber yields ninety percent of the strength per pound of carbon fiber technology. Thus, strength, production economies, reduction of fossil fuel consumption for production and transportation, all provide improved characteristics of this material whether as a core fiber, such as in fiber reinforced polymers, or standing alone as a reinforcing element.
Known scrims of polymer and plastic are flexible in varying degrees. Flexibility has been acceptable for typical usage such as structural reinforcement. Various known applications for reinforcement are stucco, plaster, structural concrete, earth for erosion control, and structural stabilization under roads. Thus, known netting is useful as a means of holding or maintaining material in some specific kind of discipline. Most are sold and transported in rolls exhibiting this characteristic. As well, most steel and aluminum scrims and stucco netting are in rolls, although some types of metal lath are supplied in flat pieces or sheets. However, even these sheets are flexible in one direction and may be flexible in both directions. These net materials have not been required to be frozen into static, hard, inflexible shape.
As an optional pretreatment before applying a principal coating or hardening layer, it may be desirable to substantially eliminate the flexibility of a net or fabric that has been placed in end position. Such a pretreatment applies a thin coating to the strands or fibers of the fabric. A net that is pretreated in end position has many notable advantages. First, the frozen net keeps material in discipline regardless of weather, such as wind, rain, snow, and the like. Second, the frozen net retains a fixed shape while a subsequent structural coating is applied. Third, the frozen net provides an initial strength, which may be compressive, tensile, or torsional. Fourth, the frozen net eliminates sagging or stretching of material. Fifth, the frozen net increases the grip or adhesion characteristic of the subsequently applied structural coating that may constitute a compressive element, while the net is a tensile element. Alternately, both net and applied coating may add compressive and tensile values. Sixth, the frozen net saves time and energy, contributing both a financial and environmental benefit.
The ability to freeze or harden some known net materials by pretreatment is specific to the chemistry of the material being utilized for the net. For some known net materials, the application of a hardener is well known. However, known processes for hardening net material require that any plastic, polymer, or synthetic coating on the net be thin enough to allow the hardener to penetrate into the coating. To overcome this limitation, this invention employs a pretreatment hardener that includes a solvent base or other chemical for temporarily softening the coating, which then allows the pretreatment hardener to penetrate the net material. The softening process is short. The thinness of the pretreatment coating allows the solvent or softener to evaporate quickly or to otherwise become ineffective after accomplishing the hardening and stiffening process. An alternative pretreatment may be performed in two steps, first by applying the solvent or softener, and second by following with a hardener that can penetrate or be absorbed by the softened fabric fibers.
Another approach to pretreatment is to harden, stiffen, or immobilize the fabric strands by coating them with an overcoat that, on a micro-scale, forms an exoskeleton by encasing the individual net strands. A suitable overcoating material must have high modulus and high tensile strength characteristics. Optionally, such material may have a fast or near instant set time in order to eliminate delay due to curing times or delay due to windy conditions. The overcoating material should be non-brittle when set. Examples of overcoatings that fulfill these requirements are urethanes such as polyurethanes, polyureas, acrylics, epoxies, and such polymer-based materials as will provide a level of efficacy for these characterized functions. In addition, cementitious base materials are desirable and may include materials that set by either hydration or polycondensation.
Pretreating by an overcoating material may be preferred over a hardening material due to several efficiencies. First, overcoating materials can be much less costly than various proprietary chemicals for hardening plastic nets. Second, applying an overcoating material can take less time, especially where a solvent must be applied prior to applying a hardening agent. Third, an overcoating agent typically can be applied in a single step, where hardening agents may require two or more application steps. Fourth, since an overcoat is on the outside of the existing net material surface, the overcoating material utilizes a greater depth of beam on micro scale and produces better strength efficiency. Fifth, the use of overcoating material may allow greater economy in selection of the net material. The overcoat or exoskeleton is analogous to the upper and lower chord of an engineered floor joist or roof rafter. In this arrangement, the net becomes structurally more efficient. A net of lower structural capacity may be used because of the compensating placement of the overcoat at a greater distance from the center of the net fiber. Further the tensile load bearing characteristics of the fiber strands may be efficiently increased again providing cost economies from utilization of less costly net materials.
With or without pretreatment, the fabric 32 is treated with the principal coating layer 34 to form a structural shell. After principal treatment, the treated net holds a fixed shape without continued need for the framework 30, as shown in
In the arrangement of layers as shown in
In optional variations of structure such as shown in
After the principal coating layer 34 has been applied to the net 32 and the net has been hardened, framework 30 may removed, as suggested in the view of
The intermediate layer 70 may be formulated to constitute an internal structural member, spacer, or insulation. As noted above, a spacer is an important element of an exoskeleton structure. There are well known formulas for computing moment of inertia of any beam or assembly. Increases in the moment of inertia are proportional to increases in the depth of member. Thus, the stated moment is increased as the distance between the center of the walls, roof, and floor, to the exterior structural member or skin is increased.
The method of this invention enables the on-site modification of building design, including both architectural design and load capacity. The thickness of layer 70 establishes the depth of beam of the exoskeleton, which is a critical factor in adapting the building structure to various loading situations. Varying the thickness of layer 70 is possible during on-site construction to accommodate changes or newly obtained requirements for the building structure. Similarly, by adding an additional layer of net and fixing material to either or both of the skins of the exoskeleton, it is possible to increase the tensile and compressive capability of the skins while at the building site.
Another optional embodiment employs structural supporting members 42 such as posts or other columns, illustrated in
A hardened net 32 may define a roof 46. Before hardening, the net is applied to roof fabric supports 48,
A folded plate is a series of triangular peaks and valleys as viewed in profile, visible in
One method of applying net 32 to supports 50 is by weaving the net over the high supports and under the low supports. Another method is to lay the net over a series of high supports, allowing slack net between the high supports. The low supports can be dropped onto the slack areas to form troughs under force of gravity. Various known fasteners and attachments such as hog rings may be used as required to attach net to supports, such as at high supports, at every support 50, or at the ends of the net 32, at the final or end supports 50. According to
The net 32 on roof 46 is hardened by application of a coating layer 34, such as a cementitious or polymeric coating layer 34 to form the base layer of finished roof 46,
The resulting triangular profile of the roof section 46 has inherent structural capacity even with rebar support removed.
Another embodiment of the roof 46 omits the low position supports 50 of
For calculation purposes, the depth of the catenaries corresponds to the depth of a structural member or beam. For example, the beam depth in
Where said roof section meets a wall, an alternate approach is to have the wall define the depth of the section at the juncture. The depth may be minimal, causing the catenary to have a compound catenary shape. The shape may be a finished roof section, or the shape may now be utilized as a mold for additional layers of materials as suggested in
A roof of the type described is suited for use on both rectangular structures and non-rectangular structures. For example, the roof is adaptable for use on round, elliptical, or various polygonal structures. Parallel arrangement of supports 50 may be preferred for use on rectangular roof areas or to produce individual rectangular roof segments. Converging radial or modified radial arrangement or segments may be preferred on rounded and irregular roof areas. In an appropriate situation, the roof may be formed of a body of hardened net 35 having no supports 50 other than at ends, as better shown and described in connection with
The roof segment 58 can be repeated as necessary to define an entire circular, elliptical, or other rounded roof by arranging the supporting elements 50 in a radiating or radial pattern, as shown and suggested by
The availability of a choice between parallel or radiating supports 50 or the substantial non-use of supports demonstrates that the roof system is adaptable to substantially any shape of building. The invention contemplates the use of all permutations and combinations of parallel, nonparallel, radiating, and other arrangements of supports. The fabric or net 32 draped over the supports 50 may be treated to form a finished section 35; or the initial section 35 may serve as a mold for additional layers 35, 70, and 78.
Roof segments 58 can be used either as downwardly dished or troughed segments such as shown in
Another configuration for a roof segment is the vault 68 shown in
As evident from the disclosures of
The multiple segments might be formed as a compound unit as suggested by
Variations in the layer structures are possible and expected. The composition of the flexible net 32 may be of woven or sheet material. Candidates include stucco netting, landscape cloth, steel chicken wire, hardware cloth, basalt net, or aluminum screen. The composition of the cloth or netting may be natural or synthetic, including plastics and composites. Examples of suitable materials include nylon, high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene, and woven plant products such as grasses, reeds, and leaves. The net 32 can be a structural component of the finished building, or, optionally, in some situations it may be removable. In the latter situation, the net may be utilized only for purpose of being a temporary method that holds or defines a shape for the cementitious material of layer 34. After layer 34 hardens, the net might be removed, leaving the layer 34 to serve as a residual structural element and as a mold for receiving and shaping subsequent layers.
As shown in
A shell 40 or other component of a building formed according to the invention may constitute an exoskeleton assembly. The hardened layer 34 defines a first external structural skin of the exoskeleton assembly. Preferably, a second external structural skin is added, consisting of at least the second hardened layer 38. In the case of compressive shapes such as vaults or domes, the inner layer 34 need add little or no structural capacity—it simply may act as a mold.
Principal hardened layer 34 may contain fibers that impart structural characteristics to the layer. Other optional ingredients include silica fume, plasticizers, or micro fibers added to the cementitious mix design. Suitable components for inclusion in the mix design are ceramic spheres, which may be synthetic or natural as present in some ashes; polymers; corn or corn derivatives, which may be by-products of processing; magnesium, such as magnesium oxides; phosphates; micro fibers, which may include round or ring shaped fibers; recyclable wastes; and other processed waste materials including phosphogypsum and mine or mill tailings. Other suitable additions include air or other materials among which may be: cements; synthetic or natural ceramic spheres; expanded polystyrene (EPS); soils; polymers; plasticizers; gelling additives; ashes such as of coal ash, rice hull ash, corn ash, bagasse ash, volcanic ash, or others; pumice; magnesium oxides; phosphates; fine powders such as calcium carbonate, waste gypsum or phosphogypsum, mine or mill tailings; and processed recyclable wastes.
In addition to layers of netting and principal hardening materials applied to the netting, an exoskeleton building construction should include one or more additional intermediate layers 70, shown in
Where layer 70 is applied to add spacing or depth to a building structure, layer 70 may be formed of honeycomb material that provides depth of structural element or beam. Optionally layer 70 is composed of expanded cementitious materials, for example expanded by air. The material forming the layer 70 may contain air or other materials among which may be: cements; geopolymers; synthetic or natural ceramic spheres; expanded polystyrene (EPS); soils; polymers; plasticizers; gelling additives; ashes such as of coal, rice hulls, corn, bagasse, volcanic, or others; pumice; magnesium oxides; phosphates; fine powders such as calcium carbonate, waste gypsum or phosphogypsum, mine or mill tailings; and processed recyclable wastes. Such materials may be used as a base raw material for a mix, or to expand a cementitious mix, regardless of whether they provide significant structural strength. The materials may have inherent compressive and tensile characteristics by themselves. The composition of layer 70 may offer insulating values to the building structure.
For economic and environmental advantage, layers 34, 38, and 70 may be fabricated from indigenous, low cost or freely obtainable materials, especially recyclable materials. Certain suitable materials may be an environmental liability to others. After such materials are detoxified, they form suitable components for use in the invention and need not be buried or otherwise stored. Some of the materials otherwise must be sent to landfill or disposed of in a manner that incurs costs. The ability to make beneficial use of such materials creates a profit center. The materials chosen are selected for utility in the invention and not on the basis of whether they are recognized by building codes or engineering standards. Likewise, it is optional whether such materials contribute significant compressive or tensile strengths.
In
As shown in
The novel method of forming the building section of
The elements of a framework 30 may be supplemented by elements 72 as shown in
Alternatively, posts or materials other than framework 30 can be utilized to position the second net or shell side 78. The frame elements 30 or alternative posts are attached to the first hardened shell side 35 to provide attachment and spacing for the opposite shell side 78 of the mold assembly. A net is attached to the second side of the posts or frame members 30 and hardened by application of a principal hardening layer as previously described. The resulting mold is filled with material 70, which is held in the mold until material 70 hardens, such as by hydration or polycondensation.
In embodiments discussed above, an intermediate layer of expanded material may be applied to the first fixed net layer to provide depth of member before the second net layer was applied and fixed to increase the load bearing capacity of the assembly. Alternately, a different shaped net, such as a folded plate configuration may be applied to the first fixed net layer to provide the intermediate space for increased depth of member. Alternately, the folded plate may be the first net to be fixed. In this embodiment, the first fixed net doubles as a first stand alone and self supporting exo-skeleton shape and secondly as the first layer of the assembly with at least one fixed net skin being applied. In these cases, the efficiencies of the intermediate spacer layer are at least partially determined by the minimization of material utilized. In other words, the efficiency of the intermediate spacer layer may be characterized in part by the percentage of that intermediate space being occupied by air. A greater percentage of air equates to greater efficiencies.
Thus, more efficient utilization of a non-linear reinforcing bar to provide the requisite spacer layer may result in less material and less labor being required. In an embodiment, the non-linear reinforcing bar may be made of basalt. However, any material that has sufficient load bearing capacities can be used. In an embodiment, the first fixed net layer may include a first flexible fabric having a tensile load bearing capacity of 20×103-100×103 psi (138-690 MPa) and a second fixed net layer that includess a second flexible fabric having a tensile load bearing capacity of 20×103-100×103 psi (138-690 MPa). In another embodiment, the first fixed net layer includes a first fixing material having a compressive load bearing capacity of 1×103-20×103 psi (7-140 MPa) and the second fixed net layer includes a second fixing material having a compressive load bearing capacity of 1×103-20×103 psi (7-140 MPa).
In the following embodiments, the first net or covering layer may be attached to the non-linear reinforcing bar. In this configuration, the non-linear reinforcing bar acts as a permanent framework. When this alternate sequence of combining the coverings with the non-linear reinforcing bar are used in a horizontal orientation, the addition of a bottom, and in some cases a top, linear reinforcing bar to the non-linear reinforcing bar may be appropriate as shown in
This embodiment has the structural advantage of having the ability to provide a shape that can more efficiently accommodate loads inherent to long spans. The previous methods of stacking up layers cannot provide this advantage. Further, as is well known to those engineers in the pre-cast concrete industry, such structurally efficient shapes have historically been made by casting the requisite tensile load bearing materials in combination with the compressive load bearing cementitious materials inside of a mold. As is known to such professionals, the mold is the required feature or assembly that defines the structurally advantageous shape for the requisite tensile and compressive materials.
The present embodiment has the advantage of minimizing the intermediate materials disclosed in U.S. Pat. No. 8,104,233. The present embodiments provide improvements in the methodology of fabricating multiple efficient load bearing shapes in monolithic assemblies by including the new reinforcing bar spacer with appropriately chosen external coverings or skins layers. The non-linear intermediate reinforcing bar spacer layer, structurally advantageously shaped, in combination with appropriately specified coverings or external layers may enable the engineer to design and fabricate, in-situ, structurally reinforced load bearing assemblies appropriate for long spans and large loads that here-to-for could only be fabricated in pre-cast concrete plants and steel fabrication plants. The traditional pre-cast components would then need to be transported to the final destination where they would typically be placed in final position of use by a crane or other heavy industrial equipment suitable for handling such loads.
The present methods overcome the challenges of load bearing applications by providing the tensile and compressive load bearing elements, in combination with appropriate depth of member, in a successive and cumulative fabrication method that achieves the required load bearing capacity as it is being fabricated in-situ or elsewhere. In other words, the constituent non-linear reinforcing bar and exterior shell or skin components may be fabricated in-place pursuant to known structural design parameters to maximize the efficiency of the structure, while minimizing the required construction infrastructure, such as the heavy equipment, trucks, cranes, steel plants, pre-cast concrete plants, transports etc.
In an aspect, the non-linear reinforcing bar spacer may define large empty spaces that may be filled only with air. For example, the non-linear structure may fill less than 10% of gap, such as less than 5% or less than 1%. In an embodiment, a non-load bearing filler, such as an insulation material, may also be added in the space between outer and inner fixed net layers.
The efficient use of intermediate shapes has been practiced in pre-cast concrete plants, structural steel fabrication plants, and even in structural wood fabrication plants. However, in all these applications, the plant was located remote from the job site. Thus, traditional methods of fabrication include the freight of the finished structural components to the site as well as the cost of the fabrication plant itself, which is typically multiple millions of dollars.
Another aspect concerns the limitation of the traditional methods in providing specified sizes and configurations of load bearing elements in assembly due to size and weight restrictions imposed by roadway authorities as well as the limitations of the roads themselves to accommodate such loads.
Embodiments of the method of fabrication provide any shape, any thickness, any height, any breadth, any length, any size that might be required. For example, load bearing structures according to embodiments may have a length of about 5-300 feet (1.5-91.5 meters) and a width of about 5-150 feet (1.5-46 meters), such as a length of about 7-175 feet (2-53 meters) and a width of about 6-40 feet (1.8-12 meters). Such assemblies do not have to be lifted or placed into their final position for use.
The load bearing structures disclosed herein may form components of building, such as walls and roofs. Further, the load bearing structures may be assembled to form a load bearing exoskeleton. In the case of roof or floor assemblies, the pre-existing walls may provide the support to properly situate the roof or floor assembly in its final position of use within the building or structure. This feature can effectively eliminate all supports, formwork, framework and mold work. Thus, the load bearing structure may be fabricated in-situ without molds, supports, formwork or framework. Assemblies that can be made with embodiments of the load bearing structures and methods include, but are not limited to, residential structures, commercial structures, bridges and dams. Alternatively, the load bearing structures may be a portion of a ship or boat, such as the hull or part of the superstructure.
An example of a reinforced load bearing structure 100 according to an embodiment is illustrated in
The load bearing structure 100 may include a top fixed layer 101 which includes a top layer reinforcing net 102 fixed in a top layer of fixative 104. The load bearing structure 100 may also include a bottom fixed layer 105 which includes a bottom layer reinforcing net 106 fixed in a bottom layer of fixative 108. Located between the bottom surface of the top layer 101 and the top surface of the bottom fixed layer 105 may be a gap 112. The depth of member D of the load bearing structure 100 may extend from the top surface of the top layer of the top fixed layer 101 to the bottom surface of the bottom fixed layer 105, and therefore may include the thickness of the top fixed layer 101, the thickness of the bottom fixed layer 105 and the gap 112.
The load bearing structure 100 may also include a non-linear reinforcing structure 110 which zigzags between the top layer reinforcing net 102 of the top fixed layer 101 and the bottom layer reinforcing net 106 of the bottom fixed layer 105. The spacing between the zigzags of the non-linear reinforcement structure is indicated by the symbol ‘b’ in
When a load is applied to the load bearing structure 100, both tensile and compressive loading are generated. The load bearing structure 100 may be designed so that the tensile load is primarily borne by the reinforcing nets 102, 106 and the non-linear reinforcing structure 110, while the compressive load is borne by the top and bottom layer of fixatives 104, 108. The area of the top layer of fixative 104 in compression may be determined by multiplying the spacing ‘b’ of the zigzag reinforcement times the thickness Tt of the top layer of fixative 104. The total compressive force C in this area is the allowable fixative material stress, such as 1,000 to 15,000 psi, times the area.
The area of the bottom layer reinforcing net 106 of the bottom fixed layer 105 may serve as a tensile resisting element with an allowable yield stress, such as from 20,000 to 170,000 pounds per square-inch (psi). The total tensile force F is equal to the allowable yield stress times the area of the tensile reinforcement. The following example illustrates a determination of the moment capacity of the load bearing structure 100 illustrated in
The depth “a” of the stress block in the upper fixed layer 101 may be determined from the area Ar of the bottom layer of net reinforcing, yield stress fy of the bottom layer of the net reinforcing, spacing b between the zig-zag reinforcement and the allowable compressive stress fc in the top fixative layer. Equation 1 below illustrates the calculation:
Given an area Ar of the bottom layer of net reinforcing of 1 in2, a yield stress fy of the bottom layer of the net reinforcing of 60,000 psi, a spacing b between the zig-zag reinforcement of 24 inches and the allowable compressive stress fc in the top fixed layer of 5000 psi, the depth “a” of the stress block in the upper fixed layer 101 is 1×60,000/0.85×24×5,000=0.6″.
With the depth “a” of the stress block in the upper fixed layer 101, the ultimate moment capacity Mu of the section can be determined with Equation 2 below:
Given an area Ar of the bottom layer of net reinforcing of 1 in2, a yield stress fy of the bottom layer of the net reinforcing of 60,000 psi, a moment arm d of 9 in. and the depth a of the stress block of 0.6 in as determined by Equation 1, the ultimate moment capacity Mu is 0.9×1.00×60,000 (9.00−0.60/2)=469,800 i-lb=19,575 f-lb/ft of width of section.
If the density of the fixative material is 144 pcf, then the weight of the material is 48 psf. Assuming the section spans a distance of 16.0 ft, the allowable uniform load is then:
q=((8×19,575/16×16)−1.2×48)/1.6=376 psf.
A span made of conventional timber beams would be lighter than the comparative embodiment. However, a timber span would support less total load. Additionally, a comparable span made of timber would cost approximately four times as much per pound of design load. A span made of glue laminated timber (glulam) is slightly heavier than conventional timber but cannot support much higher loads. However, glulam is much more expensive than timber. Thus, the cost per live load is comparable while the cost per linear foot is greater than conventional timber and much greater than a span fabricated according the teachings herein.
A 24 foot span made with steel beams without the addition of concrete, would weigh less than other conventional materials and support the highest load. However, a span made entirely of steel would be prohibitively expensive, almost eight times the cost of a span made of geopolymer reinforced with basalt.
Although the foregoing refers to particular preferred embodiments, it will be understood that the invention is not so limited. It will occur to those of ordinary skill in the art that various modifications may be made to the disclosed embodiments and that such modifications are intended to be within the scope of the invention. All of the publications, patent applications and patents cited herein are incorporated herein by reference in their entirety.
This application is a Continuation of U.S. patent application Ser. No. 13/436,123, filed Mar. 30, 2012, which is a Continuation-in-part of U.S. patent application Ser. No. 13/337,885, now U.S. Pat. No. 8,627,612, filed Dec. 27, 2011, which is a Continuation of U.S. patent application Ser. No. 11/309,015, now U.S. Pat. No. 8,104,233, filed Jun. 8, 2006, which claims the benefit of U.S. Provisional Application No. 60/595,139, filed Jun. 8, 2005, both of which are incorporated herein by reference in their entirety.
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| Number | Date | Country | |
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| Child | 14448342 | US | |
| Parent | 11309015 | Jun 2006 | US |
| Child | 13337885 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13337885 | Dec 2011 | US |
| Child | 13436123 | US |
