Abstract:
The present invention relates to a lightweight reinforced beam which utilizes a tendon system to provide tension on a rigid panel structural frame made from wood, wood composite, plastic or other material. An alternative embodiment uses a tendon system to provide tension on a precast form made from a castable material such as concrete by post tensioning a shielded tendon. This tendon, made from steel, carbon fiber or similar materials, will resist a load imposed on the reinforced beam and will support a large load relative to the weight of the tendon. Such a configuration would reduce the manpower and equipment necessary for placement and handling and transporting of such a beam, be easy and inexpensive to manufacture from a variety of materials and in a variety of lengths and sizes so as to be useful in a number of different load bearing situations, allow for post-tensioning of a shielded tendon thus shortening the length of time required for manufacture of the structure, and which would bear an equal or greater load than conventional solid beams at the point of greatest load demand thus providing for a safe, economical alternative to conventional solid beams for construction purposes.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a new and improved lightweight high load capacity reinforced beam and method of making it. More particularly, the present invention relates to a lightweight reinforced beam which would utilize a tendon system to provide tension on a rigid panel structural frame made from wood, wood composite, plastic or other material. An alternative embodiment uses a post tensioning tendon system to provide tension on a precast form made from a castable material such as concrete. This shielded tendon, made from steel, carbon fiber or similar materials, will resist a load imposed on the reinforced beam and will support a large load relative to the weight of the tendon and beam.  
           [0003]    2. Description of the Related Art  
           [0004]    Increased pressure on natural resources, environmental concerns over the depletion of forests, high energy and labor costs, and an increasing demand for affordable housing and other buildings are requiring more efficient means for providing structurally sound building materials utilizing less material from natural resources such as trees and less manpower for construction. In many instances, utilizing lightweight, high load bearing reinforced beams in place of conventional solid beams would reduce man-hours and equipment demands for use in construction.  
           [0005]    Conventional solid beams, when simply supported, utilize only a small percentage of the beam&#39;s material to resist the imposed load resting upon it. Most of the load rests on the center of the beam, where the beam is most likely to fail under the imposed load.  
           [0006]    A high load capacity reinforced beam utilizing a pre-stressed tendon to bear the load at the point of greatest demand would allow for reinforcement of the beam at that point most likely to fail under the imposed load.  
           [0007]    Such an invention could be easily adapted to components consisting of a number of different materials readily available in any given region without the need for expensive or customized adaptors or high transportation costs. In addition, the components of reinforced beams could be specifically manufactured for building codes in regions where likelihood of earthquakes or other natural disasters may dictate a specific requirement of building materials.  
           [0008]    Prestressed and reinforced beams in industry have been in use for a wide variety of applications, and is well known. The most commonly used prestressed, reinforced beams are made from concrete using steel cables or strands. Essentially, a cable is used to stress a concrete beam which adds strength to the beam. The cable may be tensioned prior to the casting operation or a shielded cable may be tensioned after the casting operation.  
           [0009]    The benefits of reinforced beams designed for use construction are well known. Examples of different types and kinds of arrangements and techniques for manufacturing reinforced beams are disclosed in U.S. Pat. Nos. 6,158,184, 5,934,835, 5,509,759, and 4,307,550.  
           [0010]    Reinforced structures for building purposes are generally known in the prior art. Such a device is described in U.S. Pat. No. 6,158,184. The claimed device comprises a lateral force resisting system which is held together by a rigid structural panel. The addition of the internal system reinforces the structure of wooden buildings against lateral force.  
           [0011]    This novel invention, is meant to resist lateral forces placed on wooden building structures from such occurrences as earthquakes and high winds which generate lateral forces upon those wooden structures. It does not, however, provide reinforcement for vertical forces such as gravity placed upon the structure.  
           [0012]    Furthermore, this inventive device utilizes wood for construction of the internal reinforcement system to supplement shear wall construction and is not intended to reduce beam weight or consumption of materials in construction.  
           [0013]    Therefore, it would be highly desirable to have a new and improved lightweight high load capacity reinforced beam and method of making same which would reduce the weight of conventional solid beams used to resist vertical forces and allow reduced manpower and equipment necessary for the placement of such beams during construction.  
           [0014]    Moreover, it would be highly desirable to have a lightweight high load capacity reinforced beam that would reduce the demand on trees, be economical to manufacture and transport and be readily adapted to a variety of sizes, materials and uses.  
           [0015]    The device described in U.S. Pat. No. 5,934,835 addresses the problem of providing for vertical stress in a prestressed beam. This unique invention uses a solid pre-cast prestressed concrete foundation pile. The device utilizes a single prestressing strand located on the longitudinal center axis. The prestressing strand is tensioned prior to casting the cement pile around the prestressed strand.  
           [0016]    The use of a pre-tensioned strand incorporated into the structure during the pouring of the cement into the mold requires that the cement must be fully cured before the prestressed strand is released. The process from pouring to complete curing slows the manufacturing time.  
           [0017]    Therefore, it would be highly desirable to have a new and improved device and method for making same for a high load capacity reinforced beam which would allow post-tensioning of a shielded cable allowing for removal of the forming mold in a shorter period of time thus shortening manufacture time.  
           [0018]    U.S. Pat. No. 4,307,550 also describes a device that utilizes a pre-tensioned strand incorporated into the structure prior to molding of the cement structure around the strand. Again, the process is lengthened due to the necessity of waiting for complete curing of the cement prior to release of the pre-tensioned strand.  
           [0019]    Therefore, it would be highly desirable to have a new and improved device and method for making same for a high load capacity reinforced beam which would allow post-tensioning of a shielded cable allowing for removal of the forming mold in a shorter period of time thus shortening manufacture time.  
         SUMMARY OF THE INVENTION  
         [0020]    Therefore, the present invention relates to a lightweight reinforced beam which would utilize a tendon system to provide tension on a rigid panel structural frame made from wood, wood composite, plastic or other material. An alternative embodiment uses a tendon system to provide tension on a precast form made from a castable material such as concrete by post tensioning a shielded tendon. This tendon, made from steel, carbon fiber or similar materials, will resist a load imposed on the reinforced beam and will support a large load relative to the weight of the tendon.  
           [0021]    It is a further object of the present invention to provide such a new and improved device and method for making same, for a lightweight reinforced beam that would reduce the manpower and equipment necessary for placement and handling and transporting of such a beam.  
           [0022]    It is a further object of the present invention to provide such a new and improved device and method for making same, for a lightweight reinforced beam, which could be made in such a manner as to be easy and inexpensive to manufacture from a variety of materials and in a variety of lengths and sizes so as to be useful in a number of different load bearing situations.  
           [0023]    It is yet a further object of the present invention to provide such a new and improved device and method for making same, for a lightweight reinforced beam, which would also allow for post-tensioning of a shielded tendon thus shortening the length of time required for manufacture of the structure.  
           [0024]    It is yet a further object of the present invention to provide such a new and improved device and method for making same, for a lightweight reinforced beam, which would bear an equal or greater load than conventional solid beams at the point of greatest load demand thus providing for a safe, economical alternative to conventional solid beams for construction purposes.  
           [0025]    Briefly, the above and further objects of the present invention are realized by providing a new and improved lightweight reinforced beam and method of making it. More particularly, the present invention relates to a lightweight reinforced beam system which uses standard commonly available materials to construct a rigid panel structural frame and an internal tendon which is post-tensioned. This post-tensioned tendon resists a load imposed in the center of the tendon. This allows a large load to be supported in comparison to the physical weight of that cable. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    The above mentioned and other objects and features of this invention and the manner of attaining them will become apparent, and the invention itself will be best understood by reference to the following description of the embodiment of the invention in conjunction with the accompanying drawings, wherein:  
         [0027]    [0027]FIG. 1 is a side elevational view of a conventional prior art solid beam;  
         [0028]    [0028]FIG. 2 a  is a longitudinal cross-sectional view of one embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0029]    [0029]FIG. 2 b  is a bottom view of one embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0030]    [0030]FIG. 2 c  is a vertical cross-sectional view of one embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0031]    [0031]FIG. 2 d  is a top view of one embodiment of the lightweight high load capacity reinforced beam constructed in accordance with the present invention;  
         [0032]    [0032]FIG. 2 e  is a side elevational view of one embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0033]    [0033]FIG. 3 a  is a longitudinal cross-sectional view of a second embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0034]    [0034]FIG. 3 b  is a bottom view of a second embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0035]    [0035]FIG. 3 c  is a top view of a second embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0036]    [0036]FIG. 3 d  is a side elevational view of a second embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0037]    [0037]FIG. 4 a  is a longitudinal cross-sectional view of a third embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0038]    [0038]FIG. 4 b  is a bottom view of a third embodiment of the lightweight high load capacity reinforced beam constructed in accordance with the present invention;  
         [0039]    [0039]FIG. 4 c  is a vertical cross-sectional view of a third embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0040]    [0040]FIG. 4 d  is a side elevational view of a third embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0041]    [0041]FIG. 4 e  is a top view of a third embodiment of the lightweight high load capacity reinforced beam, constructed in accordance with the present invention;  
         [0042]    [0042]FIG. 5 a  is a longitudinal cross-sectional view of a conventional prior art solid cement beam with pretensioned strand;  
         [0043]    [0043]FIG. 5 b  is a vertical cross-sectional view of a conventional prior art solid cement beam with pretensioned strand;  
         [0044]    [0044]FIG. 6 a  is a longitudinal cross sectional view of another embodiment of the high load capacity reinforced beam, constructed in accordance with the present invention utilizing a shielded, post tensioned tendon;  
         [0045]    [0045]FIG. 6 b  is a vertical cross-sectional view of another embodiment of the high load capacity reinforced beam, constructed in accordance with the present invention utilizing a shielded, post tensioned tendon; 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0046]    Referring now to the drawings, and more particularly to FIG. 1 thereof, there is shown a typical prior art conventional solid beamlO composed of standard metal or wood with simple supports  12  and  14  at either end of the beam. This conventional solid beam 10  is shown with a load F on the beam&#39;s center. As the load is applied, point A is in tension and point B is being compressed. As the load F is increased, failure of the beam will occur at point A or B or both depending upon the composition of the material.  
         [0047]    [0047]FIG. 2 a  depicts a longitudinal cross sectional view of one embodiment of the novel lightweight high load capacity reinforced beam constructed in accordance with the present invention. As shown, the frame of the beam assembly  20  is comprised of a top spacer member  22 , a center spacer member  24  with center bearing plate  48  and end spacer members  26  and  28 . The frame of the beam assembly  20  may be composed of any number of different materials which may include but are not limited to wood, wood composite, plastic or other material. A reinforcement assembly  30  is comprised of a tendon  32  that may be made from any number of materials including but not limited to a steel, carbon fiber or similar materials. Swaged threaded stud ends  34  and  36  are mounted to either end of the tendon  32 . The threaded portions  38  and  42  of the swaged threaded stud ends  34  and  36  extend through the end bearing plates  44  and  46  on the distal ends of the beam assembly  20  and are secured by means of retaining adjusting nuts  52  and  54 . The end bearing plates  44  and  46  are shown as protruding from the ends of the beam assembly  20 , however, the end bearing plates  44  and  46  can be embedded flush in the beam assembly  20 . Increased tension on the retaining adjusting nuts  52  and  54  allow for prestressing the beam assembly  20  against an imposed load F. This prestressing of the beam assembly  20  improves the load capability of the beam assembly  20  and decreases deflection of the beam assembly  20  when loaded. Internal diagonal spacer members  56  and  58  are positioned below the tendon  32 . These internal diagonal spacer members  56  and  58  serve to maintain the structural integrity of the beam assembly  20  and help direct the compressive forces of the load F to the center of the tendon  32 . A cross-sectional view  2 C of the beam assembly  20  is further illustrated in FIG. 2 c.    
         [0048]    Referring now to FIG. 2 b,  there is shown a bottom view of the beam assembly  20  constructed in accordance with the present invention. This view clearly illustrates the center bearing plate  48  and end spacer members  26  and  28 . The exposed tendon  32  may be seen between the internal diagonal spacer members  56  and  58 . The side beam elements  62  and  64  are located at either end of the beam assembly  20 . The threaded portions  38  and  42  extend through the end bearing plates  44  and  46  on the distal ends of the beam assembly  20  and are secured by means of retaining adjusting nuts  52  and  54 .  
         [0049]    [0049]FIG. 2 c  is a vertical cross sectional view of one embodiment of the novel lightweight high load capacity reinforced beam constructed in accordance with the present invention. The top spacer member  22  and the internal diagonal spacer member  56  are seen located between the side beam elements  62  and  64 . The cross section of the tendon  32  is located just above the internal diagonal spacer member  56 .  
         [0050]    Referring to FIG. 2 d,  a top view of one embodiment of the novel lightweight high load capacity reinforced beam constructed in accordance with the present invention is illustrated. The end spacer members  26  and  28  of the beam assembly  20  are located at either end of the top spacer member  22 . The threaded portions  38  and  42  extend through the end bearing plates  44  and  46  on the distal ends of the side beam elements  62  and  64  and are secured by means of retaining adjusting nuts  52  and  54 .  
         [0051]    [0051]FIG. 2 e  is a side elevational view of one embodiment of the novel lightweight high load capacity reinforced beam constructed in accordance with the present invention. A multiplicity of flush or recessed fasteners is represented by one flush or recessed fasteners  66  which secure the side beam element  64  to the beam assembly  20 . The threaded portions  38  and  42  extend through the end bearing plates  44  and  46  on the distal ends of the beam assembly  20  and are secured by means of retaining adjusting nuts  52  and  54 .  
         [0052]    [0052]FIG. 3 a  depicts a longitudinal cross sectional view of an alternative embodiment beam assembly  80  constructed in accordance with the present invention. As shown, the frame of the beam assembly  80  is comprised of a top spacer member  82 , a center spacer member  84  with center bearing plate  108  and end spacer members  86  and  88 . A reinforcement assembly  90  is comprised of a tendon  92  with looped end portions  95  and  97 . Threaded portions  98  and  102  are mounted to either end of the tendon  92  by means of turn buckle jaw ends  94  and  96  which are attached to the looped end portions  95  and  97  of the tendon  92 . The looped end portions  95  and  97  are secured by means of collars  99  and  103 . The threaded portions  98  and  102  extend through the end bearing plates  104  and  106  on the distal ends of the alternative embodiment of the beam assembly  80  and are secured by means of retaining adjusting nuts  112  and  114 . Again, increased tension on the retaining adjusting nuts  112  and  114  allow for prestressing the alternative embodiment of the beam assembly  80  against an imposed load F. Internal diagonal spacer members  116  and  118  are positioned below the tendon  92 . These internal diagonal spacer members  116  and  118  serve to maintain the structural integrity of the alternative embodiment of the beam assembly  80  and help direct the compressive forces of the load F to the center of the tendon  92 .  
         [0053]    Referring now to FIG. 3 b,  there is shown a bottom view of the alternative embodiment beam assembly  80  constructed in accordance with the present invention. This view clearly illustrates the center bearing plate  108  and end spacer members  86  and  88 . The exposed tendon  92  may be seen between the internal diagonal spacer members  116  and  118  located between the side beam elements  122  and  124  of the alternative embodiment of the beam assembly  80 . The threaded portions  98  and  102  extend through the end bearing plates  104  and  106  on the distal ends of the alternative embodiment of the beam assembly  80  and are secured by means of retaining adjusting nuts  112  and  114 .  
         [0054]    Referring to FIG. 3 c,  a top view of an alternative embodiment beam assembly  80  constructed in accordance with the present invention is illustrated. The side beam elements  122  and  124  of the alternative embodiment of the beam assembly  80  are located on either side of the either side of the center spacer member  84  and the end spacer members  86  and  88 . The threaded portions  98  and  102  extend through the end bearing plates  104  and  106  on the distal ends of the beam assembly  80  and are secured by means of retaining adjusting nuts  112  and  114 .  
         [0055]    [0055]FIG. 3 d  is a side elevational view of the alternative embodiment beam assembly  80  constructed in accordance with the present invention. A multiplicity of flush or recessed fasteners as represented by one flush or recessed fastener  126  secure the side beam element  124 . The threaded portions  98  and  102  extend through the end bearing plates  104  and  106  on the distal ends of the alternative embodiment beam assembly  80  and are secured by means of retaining adjusting nuts  112  and  114 .  
         [0056]    While FIG. 2 and FIG. 3 depict beam assemblies constructed in accordance with the present invention, and both of these embodiments show tendons which are adjustable at both ends, additionally, it should be noted that in both the beam assemblies of FIG. 2 and FIG. 3, the user or maker of the beam assembly needs to only have one end of the tendon to be adjustable. Therefore, alternatively, in both of the embodiments depicted in FIGS. 2 and 3, one end of the tendon could be fixed and the opposite end of the same tendon would be adjustable.  
         [0057]    [0057]FIG. 4 a  depicts a longitudinal cross sectional view of an alternative embodiment beam assembly  140  constructed in accordance with the present invention. The alternative embodiment beam assembly  140  consists of two lower diagonal beam elements  144  and  146  that are attached to side beam element  148 . Looped portions  156  and  158  of the tendon  154  are secured by means of collars  162  and  164 . The looped portions  156  and  158  are attached to the alternative embodiment beam assembly  140  by means of cross-bolts  166  and  168 . A floating top beam member  142  rests on the tendon  154 . Increased load F on the floating top beam member  142  increases the tension on the tendon  154  thus placing increased stress on the alternative embodiment of the beam assembly  140  as the imposed load F increases. Internal diagonal spacer members  144  and  146  are positioned below the tendon  152 . A cross section of the alternative embodiment beam assembly  140  is illustrated by FIG. 4 c.    
         [0058]    Referring now to FIG. 4 b,  there is shown a bottom view of the alternative embodiment beam assembly  140  constructed in accordance with the present invention. This view clearly illustrates the lower diagonal beam elements  144  and  146 . The exposed tendon  154  as well as a portion of the floating top beam member  142  may be seen between the lower diagonal beam elements  144  and  146  and the side beam elements  148  and  152 .  
         [0059]    [0059]FIG. 4 c  is a vertical cross sectional view of the alternative embodiment beam assembly  140  constructed in accordance with the present invention. The floating top beam member  142  is seen as it rests on the tendon  154 . The lower diagonal beam element  146  is located between the side beam elements  148  and  152 .  
         [0060]    [0060]FIG. 4 d  is a side elevational view of the alternative embodiment beam assembly  140  constructed in accordance with the present invention. A multiplicity of flush or recessed fasteners as represented by one flush or recessed fastener  172  secure the side beam element  152 . The top portion of the floating top beam member  142  is seen above the side beam element  152  where load F is imposed. In all cases it should be understood that load F could also be a distributed load, rather than a point load as shown here in all examples, embodiments and figures.  
         [0061]    Referring to FIG. 4 e,  a top view of an alternative embodiment beam assembly  140  constructed in accordance with the present invention is illustrated. The top of the floating top beam member  142  is located between the side beam elements  148  and  152 . A portion of the looped portions of tendon  156  and  158  are illustrated on either end of the floating top beam member  142 . These looped portions of tendon  156  and  158  are secured to the side beam elements  148  and  152  by means of cross-bolts  166  and  168 .  
         [0062]    Referring now to FIG. 5 a,  there is shown a typical prior art conventional solid beam  200  composed of precast, pre-tensioned concrete. This conventional solid beam  200  is shown with a slight crown of the beam member  202  caused by release of the tension on a prestressed cable  204 . The cable is secured on each end of the beam member  202  by means of tendon anchors  210  and  212  after the cable is threaded through bearing plates  206  and  208 . A corrosion inhibitor system may be used to protect the cable and is common practice in the industry. This prior art may also be constructed with a shielded cable which is then post-stressed. During loading of this prior art conventional solid beam  200 , the beam deflects downward, removing the crowning effect. A cross-sectional view of the conventional solid beam  200  is illustrated by FIG. 5 b.    
         [0063]    [0063]FIG. 5 b  is a vertical cross sectional view of a cement beam member  202  with pretensioned cable strand  204 .  
         [0064]    Referring to FIG. 6 a,  a longitudinal cross sectional view of an alternative embodiment of a solid reinforced beam  220  constructed in accordance with the present invention which illustrates the tendon  224  shielded by a tendon sheath or tendon channel bore  225 . The ends of the tendon  224  are held in place by tendon anchors  230  and  232  after the tendon  224  is threaded through bearing plates  226  and  228  after post-tensioning of the tendon  224 . Although the illustration indicates that the bearing plates  226  and  228  are protruding from the ends of the solid reinforced beam  220 , they may be imbedded flush in the ends of the beam member  222 . This beam member  222  may be composed of any number of castable materials which may include but is not limited to concrete.  
         [0065]    During the post tensioning of the tendon  224 , the beam member  222  is crowned upward as illustrated in FIG. 6 a.  During loading of the beam, the beam member  222  deflects downward, removing the “crowning effect”. As the load is applied, the tendon  224  increases the prestress load and compensates for the increase beam loading by increasing the prestress in the bottom area of the beam member  222 .  
         [0066]    [0066]FIG. 6 b  is a vertical cross sectional view of a beam member  222  with posttensioned tendon  224  shielded by a tendon sheath or tendon channel bore  225 .  
         [0067]    This novel alternative embodiment of a solid reinforced beam  220  can be posttensioned, which allows removal from the form sooner than a pretensioned beam. The novel alternative embodiment of a solid reinforced beam  220  also compensates for additional load by increasing the tension to the cable as the load is applied to the beam. This allows a flatter installation of the alternative embodiment of a solid reinforced beam  220  and less deflection of the alternative embodiment of a solid reinforced beam  220  during loading.  
         [0068]    It should be understood, however, that even though these numerous characteristics and advantages of the invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, chemistry and arrangement of parts within the principal of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.