EMBEDDED METAL REINFORCED STRUCTURAL ELEMENT AND METHODS FOR DESIGN AND MANUFACTURE

Abstract

The present invention relates to reinforced structural timbers. Such timbers may include an elongated structural member comprised of one or more elongated non-metallic composite materials and one or more pieces of embedded metal assembled to form a composite structural element.

Description

This application claims priority U.S. Provisional Patent Application No. 60/680,915 entitled “EMBEDED METAL REINFORCED STRUCTURAL TIMEBER” filed May 13, 2005, which is hereby incorporated by reference into this application.

FIELD OF THE INVENTION

The present invention relates to structural materials; more specifically to structural elements reinforced with metal.

BACKGROUND

BACKGROUND OF THE INVENTION—GENERAL INFORMATION

The Forest Products Society (www.forestprod.org) is the leading professional society for the forest products industry. The Forest Products Journal and the online Journal of Forest Products Business Research are published by the Forest Products Society. The primary purpose of these journals is to provide a forum for the publication of timely, rigorous, technically sound, scientific research manuscripts that focus on the forest industry. The state of the art in the field of wooden structural elements at any given time is perhaps best evaluated in light of the information presented in these journals.

The September 2004 issue of the Forest Products Journal Vol. 54 No. 9. contained an article entitled “ASTM COMMITTEE D-7: WOOD” in which the history of wood as a structural material was set out. A recent article titled “Opportunities for Wood/Natural Fiber-Plastic Composites in Residential and Industrial Applications” was published in the March 2006 issue of the Forest Products Journal, Vol. 56, No. 3. Neither of these articles contains a reference to the historic or future roles of reinforced timber as structural materials. This omission is surprising because metal attached to wood by mechanical means to improve properties has been covered in textbooks for over fifty years. Textbooks covering the design and analysis of wood-steel composite beams have been published for many years.

In February 2004, the U.S. Department of Housing and Urban Development (HUD) began publishing a periodical titled “Research Works.” The purpose of this journal was to “provide a bridge linking research and practice.”

An article titled “Design for Public Good” in the April 2006 issue contains information that may help to explain why innovation has been essentially absent from the housing industry for decades. The following quotation from this article: “If all members of the architecture profession were to contribute just 20 hours per year, the aggregate contribution would approach 5,000,000 hours this is the equivalent of a 2,500-person firm working full time for the public good.” This is reported to be 1% of the annual hours expended by the architecture profession each year or 500,000,000 hours a year. When one realizes that the architecture profession is the link between the customer and the manufacturer in the building industry, the enormity of the task of communicating the attributes of a new forest product to the customer become apparent.

Moreover, thousands of local building officials have the authority to accept or reject a building material for use within their jurisdiction. Thus it becomes obvious why the aerospace and automotive industries are decades ahead of the housing industry in the application of new materials and computer applications. A few large companies design, manufacture and market space vehicles, airplanes and automobiles and these companies are held accountable for the quality of products. Trade secrets are essential to survival in this environment and technology transfer between these industries and the building materials industry is either slow or nonexistent.

The article titled “Patently Absurd” in the Apr., 10, 2006 issue of TIME discloses some of the many challenges facing the USPTO caused by the exponential increase in applications. USPTO OG Notice: 22 Nov. 2005, “Interim Guidelines for Examination of Patent Applications for Patent Subject Matter Eligibility” provides Guidelines that are intended to assist USPTO personnel in the examination process. As mentioned in the Guidelines, applicants can assist the USPTO by being cognizant of the content of the guidance. The concept of what constitutes a “thorough search of the prior art (Section III of Notice) appears very problematic to both applicants and USPTO personnel. How does one identify the bounds of Patent literature and non-patent literature to be searched? What constitutes availability to the public? For example, the rules of the U.S. Defense Technical Information Center (DTIC) limit access to certain information to several categories of organizations and individuals. A data base search of Public STINET (www.stinet.dtic.mil) will disclose only those documents in the public information category. However, a large segment of the unclassified documents is available to many private companies that do business or research under government contracts. Even if a Public STINET search finds a document, the text of the document may not be available by electronic means. Similar problems exist for DOE and NASA data base systems. (www.osti.gov and www.nasatechnology.com). Similar questions arise with regard to research done by university students and documented in fulfillment of requirements for degrees but not published in a scientific journal. This situation becomes even more problematic when an invention draws on developments in several fields that are based on the same basic sciences, similar materials and common mathematics, but are the province of different Standards Organizations, Technical Journals and Government Agencies.

MECHANICS OF MATERIALS

Mechanics of materials is a basic engineering subject that should be understood by anyone concerned with the design, analysis, fabrication, quality control, or performance of structural elements that will be assembled into structures such as buildings and bridges. Mechanics of Materials, Fifth Edition, by James M. Gore,.(Ref.4), included herein by reference, is an example of a textbook on this subject and it served as a primary reference for preparation of this application. Chapter 5, Stresses in Beams (Basic Topics); Chapter 6, Stresses in Beams (Advanced Topics); Chapter 11, Columns, Appendix B, Problem Solving and Appendix H, Properties of Materials are especially helpful in gaining an understanding of reinforced structural elements. Properties of adhesives are not included in this book.

Adhesion Science is a very old science but it is not generally included in university courses in mechanics of materials or structural engineering. This science is considered to be in the field of chemistry and most advances in this science are made by organizations that retain the information as trade secrets. Advances in Adhesive, Adhesion Science, and Testing, ASTM International, STP 1463, (Ref. 19), included herein by reference, provides information helpful in gaining an understanding of the importance of adhesion science to wood composites and the bonding of matrix and reinforcements to obtain reinforced structural elements.

Structural Analysis, by Ronald L Sack, (Ref. 5), included herein by reference, also served as a primary reference for preparation of this application. The functional requirements for structural elements are, or should be, obtained from the analysis of the entire structure including the foundation. Appendix B, Survey Of Structural Engineering can be helpful in gaining an understanding of the differences in the capability and the practical utility of the classical, approximate or computer-oriented methods of analysis. Reinforced structural elements for complex loading arrangements can only be economically designed and fabricated by use of computer methods.

Built-up beams are by definition beams fabricated from two or more pieces of material. These pieces of material may, and usually are, composite materials. For example, natural wood is a composite material produced by nature and it is well known that the properties of wood from different trees or different parts of the same tree will not be identical. Therefore design, fabrication and analysis of structural elements of wood materials alone or wood reinforced with other materials should consider the inherent variability and uncertainty in properties of the structural element when assembled into a structure. Computer aided sensitivity analysis is the only economically practicable means for performing the necessary calculations.

The only type of wood beam that is of practical interest for structural elements that is not a built-up beam is a sawn timber. Other shapes of wood structural elements, whether reinforced or not, are, by definition, built-up beams. Such beams are also, by definition, composite beams and can be analyzed for bending stress and stiffness by well known methods. One of the objectives in designing a structural element is to use materials as efficiently as possible within the constraints imposed by function, appearance, manufacturing costs, and the like. From the standpoint of strength alone, efficiency in bending depends primarily upon the shape of the cross section. In particular, the most efficient beam is one in which material is located as far as practical from the neutral axis. Obviously, the solid rectangular sawn timber beam or a solid rectangular laminated beam of the same material would not be an economical choice if other costs for making beams with more efficient cross sections were small in comparison to the material costs. The same considerations apply to reinforced beams. Place the strongest material as far as practical from the neutral axis. In the case of reinforced wood structural elements, adhesion considerations or appearance considerations may become controlling.

PRIOR ART

Many Patents have been issued related to reinforcement of beams with glass-fiber rods, fiber-reinforced thermoplastic composites, and other non-metallic materials. U.S. Pat. No. 6,749,921 issued Jun. 15, 2004, incorporated herein by reference, presents a extensive review of this prior art. U.S. Pat No. 5,050,366 issued Sep. 24, 1991 to Gardner, et al. (expired) ('366 patent), incorporated herein by reference, describes a laminated structural timber member which is reinforced with deformed metal bars bonded with a resin adhesive within grooves. Gardner discloses many of the desirable features for metal reinforced laminated beams. U.S. Pat. No. 5,497,595 issued Mar. 12, 1996 to Kalinin (595 patent), incorporated herein by reference, discloses a reinforced sawn wood beam of standard commercial timber with a plurality of steel strips bonded within longitudinally extended kerfs. The bonding material is a two component epoxy resin. Kalinin states on page 4 that “Any type of two part epoxy resin may be used.” U.S. Pat. No. 5,026,593 issued Jul. 6, 1991 to O'Brian, incorporated herein by reference, discloses the use of thin flat aluminum strip to reinforce a laminated beam with the strip continuous across the width and length of the beam.

In each instance, the known prior art apparently assumed that the beams would be simply supported and subject to only bending loads, therefore the disclosed information is insufficient to permit computer modeling of the stresses and deflection of these beams when subjected to axial tension, compression, or lateral loading applied to the beams at connections.

In each instance, the known prior art apparently assumed that the mechanical properties of the materials in the beam would be constant between supports, therefore the disclosed information is insufficient to permit evaluation of the effects of variability and uncertainty in properties on the response of the beam to variable loads applied at variable locations.

In no instance, did the known prior art disclose an application of reinforced-wood structural element technology to the field of structural columns.

In no instance, did the known prior art disclose an application of reinforced-wood structural element technology to the field of wooden trusses.

The properties of the non-metallic reinforcements of the prior art are not disclosed in sufficient detail, if at all, to enable one to design and fabricate composite beams of known characteristics without very extensive experimentation and analysis. In general, the disclosed information is inadequate to establish if the reinforced beam would have isotropic or orthotropic properties. Wood is an orthotropic material; that is, it has unique and independent mechanical properties in the directions of three mutually perpendicular axes: longitudinal, radial, and tangential. Chapter 4 of the “Wood Handbook” (Ref. 1), incorporated herein by reference, discloses the mechanical properties of various species of wood. Mechanical properties of common metals used in structures are presented in many ASTM Standards, manuals and handbooks well known in the respective industries. Design and analysis of reinforced concrete is considered a specialized field and is not addressed in Gere. (Ref. 4.) Many advanced textbooks address the material properties and analysis of reinforced concrete structures. Building Code Requirements for Structural Concrete are addressed in ACI 318-05 (Ref.24), included herein by reference. Specialized CAE computer codes for design of reinforced concrete structures are commercially available and some of these codes are supposed to be capable of performing Virtual- Prototyping of all types of structures. Professional engineers practicing in this field are expected to have ordinary knowledge and skill in this field.

There is no known commercial source for reinforced wood structural elements in the United States. There is no known National Standard that addresses application of reinforced-wood structural elements in structural systems. This would seem to indicate that practical limitations, such as cost, technical uncertainty, codes and standards problems, or demand have prevented the inventions of the prior art from having “real world” utility. Millions of dollars have been spent, and continue to be spent, on government-funded research and development efforts to find ways to build better buildings while conserving natural resources.

In summary, the long recognized need to improve the quality of buildings, to provide affordable housing to a large segment of the population, to conserve scarce wood resources, to reduce the impacts of the timber industry on the environment, to utilize reclaimed wood, and to reduce the energy required to provide structural elements to the building construction industry have not been successful. Obviously, none of the above objectives can be accomplished without widespread commercial application of the best known technology in a timely manner. Resources wasted can never be recovered.

OBJECTS

The primary object of the present invention is to enable Structural Elements to be built to take advantage of the many advances being made in many other fields; such as reinforced concrete, adhesion science, aerospace, light automotive vehicles, computer aided design, computer aided engineering, finite element analysis, and computer aided optimization. Accordingly, objects of the present invention include:

(a) to provide a method for obtaining complete functional and non-functional specifications for input to the design of the element by the responsible supplier;

(b) to provide a method for evaluating the specifications and developing preliminary design criteria;

(c) to provide a method for applying CAD and CAE technology to aide in developing a trial design;

(d) to provide a method to interact with customer to determine if specifications should be revised to optimize cost effectiveness and reach a decision whether project should proceed or be abandoned;

(e) to provide a method for selecting an appropriate CAO program to assist in the evaluation of alternative types of elements, materials, configurations, etc. to best comply with customer's specifications and desires;

(f) to provide a method for generating structural element documentation suitable for independent review and customer approval;

(g) to provide a method for transfer of design documents to the manufacturing organization for preparation of manufacturing documents;

(h) to provide a method for the manufacturing organization to use established manufacturing processes and procedures to manufacture elements;

(i) to provide a method for verifying that the manufactured elements are of the specified quality;

(j) to provide a method to conserve resources used in structural elements by removing under-utilized materials and substituting abundant resources for scarce resources;

(k) to provide a method for using “Virtual Prototyping” to prove that a structural element has a high probability of meeting specifications;

(l) to provide a method for the in-situ modification of pre-existing structural elements to produce a modified element that will comply with pre-determined specifications;

(m) to provide a method for providing embedded metal reinforcement in the web or core of structural elements to resist shear or secondary stresses;

(n) to provide a method for using “Virtual Prototyping” to prove that adhesive joints in structural elements will have a high probability of meeting specifications;

(o) to provide a method for adapting structural elements to enable attachment to other structural elements or structures;

(p) to provide a method for using “Virtual Prototyping” to prove that attachments or connections will have a high probability of meeting specifications;

ADVANTAGES

The more important advantages of the present invention include:

• • (a) enabling the transfer of technology developed by research and development projects in many fields to improve EMRSE technology more effectively and efficiently than in the current practices;
  • (b) enabling existing commercial organizations to develop business plans based on established science, constantly changing public policy, and constantly changing worldwide economic conditions;
  • (c) reducing the time and cost required to qualify new structural elements by utilizing Virtual Prototyping technology instead of very expensive and inferior prototype testing specified in many Codes and Standards;
  • (d) placing a customer in control of risk and cost decisions instead of industry controlled organizations or local government officials.
  • (e) providing a method for reinforce pre-existing structural elements at the job site to meet new specifications or unexpected conditions.
  • (f) providing a method for connecting wood elements with the same shape but of different species or with different properties to form a structural element that optimally utilizes resources.
  • (g) providing a method to limit creep deformation in a EMRSE by adjusting the stress levels in the materials of the composite element.
  • (h) providing a method for selecting a shape for a composite structural element that will optimally utilize resources.
  • (i) providing structural elements to the Metal Plate Connected Wood Truss Industry that are stronger and stiffer than available wood elements and permit modification to element properties to accommodate stresses actually expected at various locations in the truss.
  • (j) providing a method for designing and manufacturing I-joist that are stronger and stiffer than available wood I-joist and permit modification to element properties to accommodate stresses actually expected in the I-joist.
  • (k) Providing a method for designing and manufacturing T-elements to take advantage of differing modulus of elasticity in tension or compression, or differing strength properties in tension, compression, or bending that are common in composite materials.

Accordingly, the reader will see that the teachings of this invention will enable many segments of the Forest Products Industry to supply improved products that are more environmentally friendly than those commercially available today.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to embedded-metal-reinforced-wood structural elements (EMRSE). Such EMRSE may contain one or more elongated non-metallic composite materials and one or more piece of embedded metal assembled to form a composite structural element. These EMRSE may be used in the building of structures such as homes, bridges, towers, warehouses, other dwellings and buildings where sawn timbers have historically been used. The embedded metal may be fixed firmly between two or more surfaces of non-metallic composite material and adhesively bonded to the metal in a manner that enables forces to be transmitted between materials. The metal reinforced structural element forms a basic building block that may used to form structural elements of any size, shape, or configuration. Such structural elements may include trusses, metal plate connected trusses, beams, I-beams, T-beams, box beams, columns, joists, and the like. The embedded metal reinforcements may be provided in the web or core of the element to resist shear stresses or secondary stresses.

In one configuration the EMRSE may be an elongated wood member with at least one metal piece fully embedded in the member and approximately flush with a surface of the wood structural element. The metal piece is adhesively bonded to the wood structural element. The resulting composite structural element has at least one property improved by at least a predetermined amount compared to the unreinforced structural element. The EMRSE may also contain a plurality of metal pieces that are so arranged and sized whereby the resulting composite structural element has a plurality of properties improved compared to said unreinforced structural element.

Alternatively, the EMRSE may have a first elongated wood member with one or more pieces of metal partially embedded in a groove in the wood member. A second elongated wood member also with a groove. The two wood members may be joined by adhesively binding the partially embedded metal piece in the groove of the second wood member. Such joint may be described as a tongue and grove joint. This application creates a means for joining structural elements to construct composite reinforced structural elements of various shapes and properties. This approach may be repeated to join multiple structural elements in near infinite variety of shapes and sizes. The invention also relates to structural elements where in the structural element is constructed from a plurality of pieces laminated together (a glue laminated structural element).

The metal used in reinforcing the wood structural elements may be selected from a wide variety of metals. Generally, cost and the strength, elasticity, and other properties of the metal will be considered. Such metals may include iron, steel, aluminum, copper, brass, titanium, and the like.

The structural element of the present invention may be adapted to allow the interconnection of multiple reinforced elements. Thus a structural element of almost any shape, size, and strength can be created by interconnecting such modular structural elements.

The present invention allows for the conservation of natural resources because inferior wood may be rendered useful through reinforcement with metal elements.

The present invention also relates to methods for designing and manufacturing embedded metal reinforced wood structural elements as outlined above. These methods may include receiving the functional and non-functional requirements for the structural element from a customer. The non-functional requirements may include aesthetic and price considerations as well as considerations relating to the location of the element and desired use. The functional requirements may include load and shear force requirements and other like requirements.

The received requirements may be evaluated to create preliminary design criteria. Such evaluation may be performed by computer software. The preliminary design criteria may be used to determine if an unreinforced structural element can be used. Moreover, if a catalog of predesigned structural elements exists, the preliminary design criteria may be used to select one of these elements.

Once a preliminary design for the structural element is selected, it should be determined whether the quantity of structural elements required by the customer make it economically feasible to design and manufacture them within reasonable cost constraints. If so, the customer should be provided with a preliminary cost and delivery estimate for approval or rejection. If a new structural element is to be designed, computer software should be selected for the designing and a trial design created. Computer software may also be used to optimize the trial design. Optimization includes the evaluation of alternatives for optimum compliance with specifications, material availability, cost effectiveness and resource conservation effectiveness.

After structural element is designed and or selected from a pre-existing design, design documents may be prepared for review by a customer. A contract for the building of the structural elements may also be presented at this time or later. The design documents may be transmitted to a builder or manufacturer of structural elements who can incorporate the design into a finished product using established standard manufacturing processes and quality control procedures. The completed structural elements can be marked for traceability to quality control and manufacturing documents. The final product may be transmitted to a customer for installation.

The present invention also relates to methods for modifying pre-existing structural elements to improve characteristics in the field by embedding reinforcing metal in the pre-existing structural element. Such methods may include the step of receiving up-grading specifications from a customer. Making a determination if the upgrade is feasible based on an evaluation of the specifications. The upgrading may include methods such as bonding an embedded metal reinforced structural element to a surface of the pre-existing structural member or embedding reinforcing metal in groves or holes machined into said pre-existing structural member and adhesively bonding the metal to the wood.

As with the new structural elements, suitable computer software may be used to perform preliminary design calculations and to make a trial design. The trial design calculations may then be reviewed with a customer who may make a decision on whether proceed or cancel project. If the customer gives his approval, then a suitable computer program may be used to create the final design of the reinforced element. The customer or a construction company may modify the existing structural element based on the computer generated design. For proper retrofitting of the structural element, an inspection of the modified element may be performed. The modified structural element may also be marked for quality control and traceability to the manufacturer and the design. The modified, up-graded structural element is finally transferred to the customer for use.

DEFINITIONS AND ABBREVIATIONS

Certain definitions and abbreviations used in the specification are provided below. Also in the examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided.

Computer Aided Design (CAD): The use of computer technology to assist in preparation of engineering drawings and design of Graphical Interfaces for CAE and CAO computer programs.

Computer Aided Engineering (CAE): The use of computer technology to assist in the solution of mathematical equations related to engineering problems related to design, analysis, or modeling of structures and the design, analysis, or modeling of Structural Elements.

Computer Aided Manufacturing (CAM): The use of computer technology to assist in converting CAD or CAE information into detailed manufacturing or assembly instructions or machine tool control programs.

Computer Aided Optimization (CAO): The use of computer technology to assist in the selection of an optimal Structural Element using decision criteria specified by humans.

Embedded Metal (EM): Metal fixed firmly between two or more surfaces of non-metallic composite material and adhesively bonded to the metal in a manner that enables forces to be transmitted between materials.

Embedded Metal Reinforced Structural Element (EMRSE): Elongated structural member comprised of one or more elongated non-metallic composite materials and one or more pieces of EM assembled to form a composite structural element.

Structural Element: A single joist, rafter, beam, column, truss, or other structural member that is intended for assembly into a structure;

Customer: The party that provides specifications for a Structural Element to a supplier and is responsible for paying the supplier for the Structural Element.

Person having ordinary knowledge in the field: One primary objective of the present invention is to transfer technology developed or under development in many fields, such as aerospace, automotive vehicles, finite element analysis, adhesive bonding of diverse materials, and engineering wood composites to the structural wood products field. Therefore, it must be recognized that one person, or even one organization, is unlikely to have the knowledge to design and manufacturer the more advanced embodiments of the present invention. This application was written based on the assumption that Professional Engineers in the appropriate sciences and experienced manufactures in the wood products industry would contribute to the commercialization of the EMRSE technology disclosed in this application. Accordingly, many references are provided to assist the reader in obtaining information from fields in which he may have limited knowledge.

Wood: This term includes natural wood, structural composite lumber, engineered wood, particle board, and wood composite materials of all types. It does not include plastic materials that are not wood composite materials.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawing. These drawings depict only typical embodiments of the invention and are not, therefore, to be considered to be limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings.

FIG. 1 is a perspective view of a prior art glue laminated beam reinforced with metal rods.

FIG. 2A is a side perspective view of a glue laminated beam.

FIG. 2B is a cross-sectional view of the metal reinforced beam of FIG. 2A.

FIGS. 2C and 2D are cross-sectional views of metal reinforced structural elements.

FIG. 3A is a top plan view of a preexisting structural element.

FIG. 3B is a side plan view of a structural element with embedded metal.

FIG. 3C is a cross-sectional view of a preexisting structural element reinforced with the methods of the present invention.

FIG. 4A-J are cross-sectional views of various configurations of metal reinforced structural elements.

DETAILED DESCRIPTION OF THE INVENTION

It will be readily understood that the components of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus, system, and method of the present invention, as represented in FIGS. 1-4 is not intended to limit the scope of the invention, as claimed, but is merely representative of certain embodiments of the invention.

Preferred Embodiment

It is not possible to describe a preferred embodiment of EMRSE technology because the statement of the problem (specifications) establishes the form and function of the structural element and the details of the design and manufacturing processes used to obtain an optimal EMRST. Many types of reinforced beams could be built to meet most functional specifications for simple beams with simple loading configurations and lengths required for conventional structures. However, advanced structural engineering and mechanics of materials technology, becoming more widely understood and used today, are required to solve complex problems and provide optimal EMRSE

Methods

The procedures used in solving engineering problems will vary among individuals and will vary according to the type and complexity of problem. In general, the methods of the present invention are based on those suggested in Section B.2 of Gere. (Ref.2) Additional consideration was given to the recommendations of ANSI/TPI 1-2002 “National Design Standard for Metal Plate Connected Wood Truss Construction” (Ref. 18), incorporated herein by reference, because professional engineers, professional architects, wood product manufactures, and building officials generally have access to this and other related ANSI Standards.

When planning and building a structure, the functional requirements for structural elements are generally set forth in structural element design specifications derived from structural system design documents. Non-functional requirements are generally established by an architect or a customer of the architect. Although the non-functional requirements are not subject to review by the local building authority, protective covenants or zoning regulations may limit alternatives available to the customer. Historically, structures were designed by architects, draftsman, building contractors, etc., materials were selected from Specifier Guides, Catalogs, or whatever was available in stock in the local lumber yard, and assembled on location by experienced craftsmen. Present day construction methods as described by Newman, (Ref. 3), herein included by reference, do not differ significantly from these historical methods.

The methods of the present invention envision a process similar to that described in ANSI/TPI 1-2002 (Ref. 18). EMRSE are manufactured composite structural elements that can only be optimally designed and manufactured with the aide of advanced computer technology using ever improving adhesives and manufacturing methods. Specialization in every field has limited the ability of one, or a few individuals, to complete projects without the assistance of people with more detailed knowledge of a specific science and industrial manufacturing methods. Early work on the application of finite element analysis, failure theory, and fracture mechanics to structural beams is reported in a dissertation by Cheng titled “A Computer Simulation and Analysis of Strength and Failure for Glue Laminated Beams”, (Ref. 20), included herein by reference. He had success in demonstrating technical feasibility. Unfortunately, the computer software developed by Cheng was not published, and even if it were available today, it would be obsolete. The repaid developments in CAD, CAE, CAO, and Virtual-Prototyping technology suggests that effective and efficient application of these technologies in the field of EMRSE will require that current computer programs be selected from those economically available to an organization at the time the specification is received. Cheng and other known works assumed that adhesive joints between laminations were reliable and could be disregarded in the analysis. This assumption was consistent with experimental evidence from testing of glue laminated beams made from one species of wood using proven adhesives and processes common in the industry. However, it is well known (Ref. 11) that this assumption must be validated when using different adhesives or different adherents. Virtual-Prototyping of adhesive joints will be required to perfect economically viable EMRSE technology for mass production using many different species of wood.

Adhesive joint technology has been the subject of extensive research in the aerospace and automotive fields for over twenty years. Research reports on this work generally available to the public typically are delayed for five to ten years after results are known in the specialized fields of the research. A report titled “Adhesive Bonding Technologies for Automotive Structural Composites”, ORNL/TM-2001/2, (Ref 21), included herein by reference, contains information applicable to Virtual-Prototyping in the EMRSE field. Extensive research is on-going in the application of hybrid joining technology in the automotive industry. Commercial Virtual Prototyping programs suitable for application to EMRSE needs are either available currently or will soon be available.

Connections between wood structural elements and concrete and steel members are problematic and many building failures have been traced to design and construction defects in these connections. An entire industry has developed to provide wood construction connectors to the building industry. The Simpson Strong-Tie Co. is a leading supplier of wood construction connectors and their Catalog C-2003 (Ref. 22), included herein by reference. Gardner ('366 patent) discloses in FIGS. 6 through 18 and associated discussions a number of concepts for using deformed metal dowels bonded with resin adhesive for connections to avoid problems with standard metal fasteners. No calculations or test data are disclosed to verify that these connections would be practicable. However, the EMRSE technology could employ this type of connection without restriction to deformed rods and resin adhesives.

Chapter 8 of Appendices to ANSI/TPI 1-2002 (Ref. 18) contains procedures that are necessary for designing a metal connector plate to adequately resist all applicable design forces and moments acting at a joint, including a determination of the minimum required metal plate contact area and the minimum net sections of the plate based on the plate lateral resistance, tensile and shear strengths, and the allowable axial tension and compressive stress of the wood over a reduced net section at the joint. Use of SBMRSE in such trusses will require modification to plate designs. This Standard does not recognize either reinforced structural elements or adhesively bonded metal plates and relies upon teeth in the plates or nails to resist the forces between the plates and the wood. Hybrid joining technology and Virtual-Prototyping technology developed for the automotive industry (Ref. 21) would solve this problem by bonding the plates to the wood with much greater strength and reliability than current technology.

A report titled “Feasibility of Fiberglass-Reinforced Bolted Wood Connections” (Ref. 23), included herein by reference, presents data that show that even a small amount of adhesively bonded reinforcement can change the failure modes of bolted connections in wood structural members. Metal gusset plates either embedded in wood or on the surface of the wood and adhesively bonded to the wood could prevent shear plug or splitting failures. The method of adapting EMRSE by adhesively bonding metal to the EMRSE to enable strong and reliable connections to other structural elements or supporting members is one method for adaptation. Obviously, the optimal adaptation of an EMRSE to enable connections to other members will be affected by the specifications.

Structural elements of different types are generally manufactured in different facilities using different processes. It is envisioned that EMRSE of the present invention will likely be mass produced in some of these same facilities. Manufacturers must be free to develop proprietary processes for manufacture of EMRSE, without being limited by patents, in order to have a free competitive market for EMRSE. This is consistent with current industrial practice in the field such as the manufacture of glue laminated beams, manufactured lumber, and trusses.

Steps in the methods should provide reasonable assurance that the customer can verify that structural elements conform to specifications and are of the specified quality before accepting delivery of the product. Such assurance is generally not available for wood structural elements produced by current methods.

Steps in the method should provide for marking each structural element for traceability to manufacturing and quality control documents. It is envisioned that thousands of essentially identical EMRSE will be produced by each manufacturer. A data-base containing such information could be used to provide customers with a Specifier Guide. An example of such a guide is the “Western Engineered Wood Products Specifiers Guide” (Ref. 8), included herein by reference.

The present invention provides methods to design and fabricate wood laminates reinforced with embedded metal for use in the manufacturing stronger and stiffer glue-laminated beams. Moreover, the methods of the present invention may also be used to reinforce prefabricated and/or previously installed sawn lumber beams, manufactured lumber or glue-laminated beams with embedded metal. The method allows a user, such as a structural engineer to design a reinforced beam by inputting moment, shear, the dimensions, and other functional requirements for the beam into a computer program. The beam design engineer can use the computer software to determine the beam parameters such as modulus of elasticity and section modulus as functions of beam length. He may also use computer software to select flange laminates to provide the required section modulus and stiffness for the beam. Next he uses computer software to select the laminate or laminates for the web of the beam to place between the flanges. The detailed beam design is computer generated beam lay up drawings, material specifications and fabrication instructions. The beam design can be used to manufacture the beam using the machines and procedures normally used for glue-laminated beam fabrication. If an existing beam is to be reinforced to meet new requirements, the existing beam properties are input to the computer software and a flange laminate or laminates are designed to be added to the beam in the field. Alternatively, reinforcements may be designed to be installed in grooves cut into the existing beam.

In certain configurations steel can be used as the reinforcing material, however it will be appreciated that other metals may be selected depending on a variety of factors including cost and desired strength. Generally the reinforcing material may be adhered to the beam with an adhesive such as epoxy or other water resistant adhesives. Primers may be used in some applications prior to laminating the reinforcing material to the beam with the adhesive. Price and availability of materials may be input to the computer software to optimize the cost effectiveness of the design.

EXAMPLES

The present invention can be further described by the following specific examples:

Example I

Computer Model Verification with Benchmark Data

FIG. 1 shows the prior art beam as disclosed in the '366 patent. A computer model was made for this beam using an unpublished computer code designated herein as TRANSFORM X, which is a research program of limited capability that does not use finite element methods. TRANSFORM X is an adaptation of a computer code designed for other purposes and is discussed by Hernandez. (Ref. 15). Cheng reported good agreement between the method of Hernandez and his finite element methods. (Ref. 20) Because TRANSFORM X is a research code and has not been verified for general use, it was necessary to benchmark it for use in this specific application, and Gardner's data was the only available data relevant to embedded metal reinforced glue laminated beams. Gardner did not report calculated or measured stress data and without these data he was apparently unable to perform a failure mode and effects analysis. TRANSFORM X has the capability to analyze beams with laminations of different properties along the length of the lamination, provide stress distributions between laminations, and deflection at the center of the beam for two point loading. However, it will be appreciated that more powerful commercial CAE computer codes are available and would be required for effective commercialization of the EMRSE technology. In order to relate the observed deflections to stress levels in the steel and the wood as well as to observed failure information, a computer model was made for the beam. It will be appreciated that other computer simulators other than TRANSFORM X may be produced to perform the same calculations.

The specification for the beam, as obtained from the '366 patent information, were as follows: length of beam is 236 in., width of beam is 3.3 in., depth of beam is 11.6 in., number of laminations is 8., thickness of each lamination is 1.45 in., modulus of elasticity of the wood is 1,450,000 psi., modulus of elasticity of steel is 30,000,000 psi., design load is 6050 pounds, test load is 12,300 pounds, half of the load is applied at 78 in. from each end. The deflection limit at design or test loads was not included in the specification.

The load versus deflection data from the computer model agreed well with the '366 patent's data. The peak stress in the wood at design load was calculated to be 1,500 psi., while the peak stress in the steel was calculated to be 25,000 psi. These stresses are within the elastic limits for the materials and indicate an efficient use of the steel. The corresponding stresses at the acceptance test load were calculated to be 3,100 psi. and 41,000 psi. The corresponding stresses when cracks were observed in the tension side wood were calculated to be 4,100 psi. in the wood and 68,000 psi. in the steel. The estimated yield point of rebar steel is 60,000 psi. so yielding of the steel could have contributed to the partial failure of the wood. The corresponding stresses at the load recorded at the failure point of 20,600 psi. were calculated to be 5,200 psi. in the wood and 85,000 psi. in the steel. After the failed beam was reloaded to 11,000 pounds, which is about twice the design load, it held this load at a total deflection of 5.65 in. This behavior is consistent with what could be expected from a steel beam following such an event. It is informative to evaluate the reported deflection data in light of deflection limits allowed by codes and desired by customers. A deflection limit is generally specified in term of length divided by a specified constant. The values for the constant typically fall in the range between 180 and 960, where the lower value is for roof elements not subjected to large live loads, and the higher value is for stiff floor beams. The '366 patent beam would meet a deflection criteria of L/240 at the design load but could only meet an L/960 criteria at a load of 1500 pounds. This points out the common problem encountered with previous art structural element technology in which the strength is excessive when deflection is the controlling factor.

Example II

Redesign of Reinforcement of '366 Beam

Referring now to FIG. 2, as an illustration of the EMRSE technology of the present invention, it was assumed that the material properties for the flange, design load, and test load parameters of Example I, and the deflection characteristics measured for the Example I beam were input specifications for an EMRSE. The design approach was to consider the top and bottom laminations as reinforced laminations and the center laminations would be designed as the WEB of the beam in order to use low grade lumber in the WEB. An additional design objective was to reduce the amount of steel required in the flange. The TRANSFORM X program was used as the CAE program for the problem.

The TRANSFORM X computer model requires that the reinforced laminate is modeled as two laminations of a combined thickness of 1.45 in. An initial thickness of the steel was assumed to be 0.75 in. to agree with standard bar stock. Groove depth was selected as 0.75 in., leaving 0.7 in. of wood. A slightly deeper groove would be required in a practical beam but this detail was unnecessary to model in the simulation. A modulus of elasticity for the core lamination of 500,000 psi was selected as being a reasonable assumption for a very low grade wood. The TRANSFORM X results gave a deflection at design load within three percent of the '366 patent's experimental results. Peak bending stress in the outer fiber of the wood was within one percent of that calculated for '366 patent's beam. Peak bending stress in the steel was seven percent higher than for the '366 patent's beam but the steel area was reduced by twenty five percent. Peak bending stress is the core lamination was 360 psi., which is much less than the design strength of 500 psi. allowed for stud grade lumber. These calculations indicate that the methods of this invention can meet the objective of providing glue-laminated beams of standard quality using low grade lumber that are two to three times stronger than all wood beams of the same size. These calculations also indicate that large beams could have a large cavity in the center without changing stiffness or strength significantly. Thus opening the way for building box beams using glue-laminated technology and existing manufacturing facilities. Manufacturers would have the opportunity to use many sizes and pieces of what is now scrap lumber in the webs of glue-laminated beams providing that care is taken to provide the necessary shear and crushing strength in the web. WEB reinforcements could be provided by embedding steel in the WEB as is common in reinforced concrete.

Reinforced laminates with equivalent properties could be designed with many arrangements of the steel locations. Two alternates for the example beam are worth mentioning. Two pieces of steel of the same thickness and one half of the width could be located near the edges and improve the moment of inertia about the vertical axis and improve beam stability. This arrangement could be desirable for reinforced laminates for I-joists. The steel could also be placed in grooves in the edges of the laminate and accomplish the same objectives. Slightly more steel would be required to obtain the same deflection characteristics. The geometry of the grooves and the steel could be changed over a wide range as long as the moment of inertia and stiffness of the beam remained within specified limits.

Example III

Reinforcement of Pre-existing Beam

Referring now to FIG. 3, an example of the use of EMRSE technology to convert a preexisting wood structural element in an existing structure to an EMRSE complying with customer specifications will be illustrated.

The sides and bottom of the pre-existing beam should be exposed to allow for access and examination of the beam. The mechanical and physical properties of the beam could be estimated or measured and them be input into proper design calculations. It will be appreciated that such pre-existing beams may not be balanced in load or strength, therefore additional calculations may be required. However, for the purposed of this example, a balanced beam was used. The dimensions of the example preexisting beam are as follows: length of beam is 240 in., width of beam is 8 in., depth of beam is 16 in., depth of damaged wood on top and bottom is 1 in., thus leaving an effective beam depth of 14 in., the centers of the reinforcement were assumed to be 3.5 in. from the top and bottom of the actual beam. The pre-existing beam was assumed to be made of structural grade Douglas fir having a modulus of elasticity of 2,000,000 psi.

It was assumed that the specification for the EMRSE required that the stiffness of the preexisting beam, when new, be increased by fifty percent by the modification and that the modified beam would not experience significant creep deformation over a thirty year period.

Design calculations were made using the TRANSFORM X program as a design aid and 1.5 in. wide by 1 in. deep reinforcing steel was found to meet the design requirements. Peak stress in the wood was reduced by sixty percent compared to that in the original beam. The steel was assumed to be embedded into grooves cut in the beam and adhesively bonded with epoxy to wood primed with a primer of the type disclosed by Vicks in U.S. Pat. No. 5543487 ('487 patent).

Example IV

Alternative Configurations

FIG. 4 shows the cross sections for some EMRSE that could be produced using the principles and concepts of this invention. In principal, any type of joint that uses a tongue and groove configuration where the tongue is made from metal and the grooves are machined in the wood is within the scope of EMRSE technology.

The previous example embodiments do not require vertical reinforcement in the EMRSE. Some embodiments may require such reinforcements to accommodate vertical and horizontal shear stresses, or compressive stresses similar to that required in concrete beams or columns. Such reinforcements of EMRSE could be provided by embedding the metal in a vertical direction in the surface of the wood or by drilling a hole in the wood and bonding the wood to the metal with an adhesive as is done when installing metal rods in concrete to provide anchors. This same technology could be used to install anchors in the EMRSE on either the ends or sides of the timber.

Reinforcing metal can be made in many shapes. Plain rods, plain bars, deformed rods, deformed bars, stranded cables and coated configurations are commonly used in concrete. Any of these and others could be adapted to EMRSE.

Pre-tensioning and post-tensioning methods have been developed for concrete beams and these could be adapted to EMRSE.

Standards for timber and Glue-laminated beams are currently based on strength requirements rather than on stiffness requirements. When the application requires the design to be controlled by stiffness requirements the beams are often over designed for strength. Wood and wood composites have natural relationships between stiffness and strength and the upper limit for the modulus of elasticity of wood is about two million psi. This relationship sets a lower limit on the depth of a wooden beam that can be designed to meet a stiffness requirement. EMRSE technology offers much greater flexibility because steel has a modulus of elasticity of about thirty million psi and is available in a wide range of strengths.

Utility

The history of the adoption of innovations in the tradition-bound forest products industries indicates (Ref. 17), incorporated herein by reference, that the greatest impediment to utilization of EMRSE technology will be educating people within the industries and their customers about the merits of this technology. The recent changes in public policy regarding resource conservation and the exponential increase in the cost of many commodities should provide incentives for industry to become more accepting of new technology. The most important objective of the present invention is to provide a means for encouraging and expediting the acceptance of EMRSE technology on a scale that will provide significant public benefit. Fortunately, the various segments of the industry, such a manufactured lumber, glue laminated structural elements, trusses, I-joist, and saw mills can independently implement changes. Capital costs for plant modifications should be minimal and incremental as production grows. The so-called voluntary or industry Standards are probably the biggest impediment to rapid and large scale acceptance of EMRSE technology. Book Publishing Organizations without any accountability write most of these codes and standards and include the words “national” or “international” in the name of the organization and in the titles of the books they publish, although there is no federal agency that has any control over what is in the books. Each state, each county in each state, and each city in each state makes a decision with regard to enacting local ordinances to give the book the force of law. The Building Codes provide that the Building Official can approve or disapprove the use of a building material. The consumer does not generally have a practical means to obtain judicial review. Thus a manufacturer of a new and innovative product is placed at a considerable disadvantage compared to a supplier of an established product. Perhaps the greatest opportunity to use the EBMRST technology is in modification or repair of structural elements on the job site.

Once the teachings of this invention become widely known, anyone with a few standard carpenter tools and a caulking gun could practice the invention, but he would be unlikely to know the mechanical properties of the product produced. Consumers will therefore be forced to rely on products backed by comprehensive Warranties, and authorized contractors to avoid inferior products and structures.

References

U.S. Pat. Nos. 6,749,921, 6,012,262, 6,358,352, 5,026,593, 5,497,595, 5,050,366 (Expired), 5,543,487, 5,547,729, 4,615,163.

The reference numbers cited herein correspond to the same references numbers used in Provisional Patent Application No. 60/680,915

Reference 1: “Wood as an Engineering Material”, Wood Handbook, Gen. Tech. Rep.FPL-GTR-113, 1999, Forest Products Laboratory USDA.

Reference 2:ASTM Vol.04.10, Wood, American Society for Testing and Materials.

Reference 3: Newman., “Design & Construction of Wood-Framed Buildings,” McGraw Hill, 1995, ISBN 0-07-046363-8.

Reference 4: Gere, “Mechanics of Materials” Brooks/Cole, Fifth Ed., 2001.

Reference 5: Sack, “Structural Analysis”, McGraw Hill, 1984.

Reference 6: Engineered Wood Composites for Navy Waterfronts, “Project End Report,” June, 2001, Washington State University.

Reference 7: Dansoh, “Bending strength and stiffness of glued butt-jointed glulam”, Forest Products Journal, Vol. 54, No. 9.

Reference 8: Boise Cascade, “Western Engineered Wood Products Specifiers Guide”, Boise Cascade Corp.,WSG/2003

Reference 9: American Society for Testing Materials (ASTM),1991, “Standard test methods for establishing stresses for establishing stresses for structural glue-laminated timber”.

Reference 10: ASTM Vol. 15.06, Adhesives, American Society for Testing Materials.

Reference 11: Christiansen, “Improvements to hydromenthylated resorcinol coupling agent for durable bonding to wood,” Forest Products Journal Vol. 53, No.4.

Reference 12: Hernandez, “Strength and Stiffness of Reinforced Yellow-Poplar Glued-Laminated Beams”, FPL-RP-554, Forest Products Laboratory USDA.

Reference 13: Davids, “Fatigue of glulam beams with fiber-reinforced polymer tension reinforcing”, Forest Products Journal Vol. 55, No. 1.

Reference 14: Markwardt, “Strength and related properties of woods grown in the United States”, USDA Technical Bulletin No 479, September 1935.

Reference 15: Hernandez, “Probabilistic Modeling of Glued Laminated Timber Beams,” Wood and Fiber Science, Vol. 24, No. 3, 1992.

Reference 16: Hinckley, “The Role of Variation, Mistakes, and Complexity in Producing Nonconformities,” Journal of Quality Technology Vol. 27, NO. 3, July 1995.

Reference 17: Shook,“Adoption of Innovations in Tradition-bound Industries: Uncertainty and Competitive Rivalry Effects on Adoption of Wood Products”, Journal of Forest Products Business Research, Vol. 1, No. 1.

Reference 18: ANSI/TPI 1-2002, “National Design Standard for Metal Plate Connected Wood Truss Construction, including Commentary & Appendices”, Truss Plate Institute, 2002, Madison, Wis. 53719.

Reference 19: ASTM STP 1463,“Advances in Adhesives, Adhesion Science, and Testing”, ASTM International, ISBN 0-8031-3489-4.

Reference 20: Cheng, “A Computer Simulation and Analysis of Strength and Failure for Glue Laminated Beams”, Washington State University, May, 1994.

Reference 21: ORNL/TM-2001/2, “Adhesive Bonding Technologies for Automotive Structural Composites”, Oak Ridge National Laboratory, Feb., 2001.

Reference 22: Simpson Strong-Tie Co., Inc.,“Wood Construction Connectors, Catalog C-2003”, Jan., 2003, Simpson Strong-Tie Co., Inc., Dublin, Calif. 94568.

Reference 23: Windorski, “Feasibility of Fiberglass-Reinforced Bolted Wood Connections”, FPL-RP-562, Apr., 1997, Forest Products Laboratory, Madison Wis. 53705.

Reference 24: ACI 318.05,“Building Code Requirements for Structural Concrete”, American Concrete Institute, Farmington Hills, Mich. 48333.

Claims

1. An embedded-metal-reinforced-wood structural element.

2. The structural element of claim 1 wherein said structural element comprises an elongated wood member; at least one metal piece fully embedded in said member and approximately flush with a surface of said wood structural element; means for adhesively bonding said metal piece to said wood structural element; whereby the resulting composite structural element has at least one property improved by at least a predetermined amount compared to said unreinforced structural element.

3. The structural element of claim 2 wherein a plurality of metal pieces are so arranged and sized whereby the resulting composite structural element has a plurality of properties improved compared to said unreinforced structural element.

4. The structural element of claim 1 wherein said structural element comprises a first elongated wood member; at least one metal piece partially embedded in a groove in said wood member; a second elongated wood member containing a groove; means for adhesively bonding said metal piece within the grooves of the first and second wood members, the grooves and metal forming a tongue and groove joint creating a means for joining structural elements to construct composite reinforced structural elements of various shapes and properties.

5. The structural element of claim 4 wherein a plurality of metal pieces are embedded in a plurality of grooves in a plurality of said wood members thereby providing a composite reinforced structural element of various shapes and properties.

6. The structural element of claim 4 comprising; a) plurality of elongated wood laminae of predetermined configuration and properties; b) at least one laminate described in claim 4: c) means for bonding the laminae to form a composite structural element; whereby said reinforced structural element has a configuration and properties conforming to predetermined specifications.

7. The structural element of claim 1 is a composite structural element of a type known as a metal plate connected wood truss.

8. The structural element of claim 1 is a composite structural element of a type known as a I-beam.

9. The structural element of claim 1 is a composite structural element of a type known as a box beam.

10. The structural element of claim 1 is a composite structural element of a type known as a column.

11. The structural element of claim 1 is a composite structural element of a type known as a T-beam.

12. The structural element of claim 1 wherein the preferred reinforcing metal is selected from a group of metals pieces whereby the said structural element will optimally conform to predetermined specifications.

13. The structural element of claim 1 wherein the preferred wood is selected from a group of wood elements whereby the said structural element will optimally conform to predetermined specifications.

14. The structural element of claim 1 wherein materials and processes for making adhesive joints are selected from a group of materials and processes; whereby said structural element will optimally conform to predetermined specifications.

15. The structural element of claim 1 wherein the structural element is adapted to enable attachment to other structural elements or structures.

16. The structural element of claim 1 wherein natural resources are conserved by removing underutilized materials and substituting abundant resources for scarce resources.

17. The structural element of claim 1 wherein embedded metal reinforcements are provided in the web or core of the element to resist shear stresses or secondary stresses whereby said structural element will optimally conform to predetermined specifications.

18. A method of designing and manufacturing embedded metal reinforced wood structural elements comprised of elongated wood structural elements; pieces of reinforcing metal embedded in the wood elements; means of adhesively bonding the reinforcing metal to the wood elements; adapting the composite reinforced structural elements to enable the connection of structural elements to other structural elements and to supporting members of various materials; the method comprising the steps of:

a) receiving functional and non-functional requirements for the structural elements from a customer,

b) evaluating the requirements to select preliminary design criteria and determine if an unreinforced structural element would satisfy the customer's requirements,

c) evaluating the design criteria to determine if a existing design for a embedded metal reinforced structural element would satisfy the customer's requirements,

d) evaluating quantity of structural elements required by the customer and determine if special structural elements could be designed and manufactured within reasonable cost constraints; if so, provide the customer with a preliminary cost and delivery estimate for approval or rejection,

e) selecting a computer program suitable for required design assistance and complete a trial design,

f) selecting a suitable computer optimization program for design optimization and evaluate alternatives for optimum compliance with specifications, material availability, cost effectiveness and resource conservation effectiveness,

g) preparing design documents and draft contract for customer review;

h) transmitting design documents to a manufacturing organization for preparation of manufacturing documents,

i) manufacturing structural elements using established standard manufacturing processes and quality control procedures,

k) marking structural element for traceability to quality control and manufacturing documents;

l) delivering structural elements to customer.

19. A method for modifying pre-existing structural elements to improve characteristics in the field by embedding reinforcing metal in said pre-existing structural element comprising the steps of:

a) receiving up-grading specifications from a customer,

b) evaluating the specifications to determine if up-grading is feasible, and if feasible, employing a method selected from the group consisting of bonding an embedded metal reinforced structural element to a surface of the pre-existing structural member and embedding reinforcing metal in grooves or holes machined into said pre-existing structural member and adhesively bonding the metal to the wood,

c) using a suitable computer program to perform preliminary design calculations and to make a trial design,

d) reviewing the trial design calculations with customer and obtaining a decision on whether proceed or cancel project;

e) if approval to proceed is obtained, using a suitable computer program to aid in final design and preparation of modification documents;

f) providing construction organization with drawings and procedures to effect modifications;

g) making specified modifications using either standard or special procedures and methods known to the construction organization,

h) inspecting work for conformance with specifications and quality control procedures,

i) marking modified elements for traceability to quality control and modification documents, and

j) transferring up-graded structural element to customer.