Patent Publication Number: US-2006000152-A1

Title: Buckling and shearing opposing reinforcement bracket for wooden I-joist

Description:
CROSS REFERENCE  
      The present application is a Continuation in Part of U.S. patent application Ser. No. 10/410,505 titled “Buckling Opposing Support for I-joist” of the same inventor, filed 04108/2003. 
    
    
     FIELD OF INVENTION  
      The present invention relates to reinforcement brackets for wooden I-joists. Particularly, the present invention relates to brackets for buckling and shearing opposing support of a wooden I-joist having a web hole exceeding the wooden I-joist&#39;s modification limits.  
     BACKGROUND OF INVENTION  
      I-beams are well-known profiles designed for carrying static loads with a minimal own weight. An I-beam has a cross section similar to that of a capital “I” with top and bottom chords that are vertically spaced apart by a central web portion. A special type of wooden and/or wood like I-beam is used in architectural constructions. This type of I-beam is known as I-joist. I-joists are described, for example in U.S. Pat. No. 4,195,462 to Keller and U.S. Pat. No. 6,460,310 to Ford et al.  
      I-joists are configured for carrying maximum loads while keeping their own weight to a minimum. For that purpose, I-joists have top and bottom chords with enlarged cross sections where compressive and tensile stresses are at a maximum. A central web portion connects both chords and keeps them at a distance and in plane with the load direction. The central web is also symmetrically positioned with respect to both chords. Under load the chords tend to deflect in plane with the applied load and consequently in plane with the web. The web is configured to provide sufficient stiffness and strength against the deformation tendency of the chords.  
      The web has a relatively thin cross-section geometry, which results in a certain buckling tendency of it. The buckling tendency of the web portion is a major criterion for the over all load carrying capacity of an I-joist. The structural integrity of the web is often compromised in architectural constructions. To assure sufficient buckling resistance of the modified web, manufacturers may provide dimensional safety limits for maximum diameter and other critical dimensions for holes cut into the web. Unfortunately, such standards are often not met by the construction workers that are typically in charge of fabricating the holes into the web. In a progressing architectural construction where access to the I-joist&#39;s web portion is already impaired, it becomes difficult to control the holes cut into the webs. Therefore, there exists a need for assuring the I-joists static load capacities irrespective of the actually hole shape cut into a web. The present invention addresses this need.  
      Reinforcement brackets for modified structural beams are well-known in the art. For example, U.S. Pat. No. 5,519,977 to Callahan et al (1). describes a reinforcement bracket for modified sections of a wooden joists. The invention is configured for joists with rectangular cross section. Support is mainly provided by configuring the bracket as a profile protruding in direction of the beam and having bending resistance that is maximized in protrusion direction of the joist. An eventually increased buckling tendency of the modified joist is not addressed by the invention. More over, the bracket attached at the modified joist offsets the all over section modulus of the combined cross section of joist and bracket out of the load plane. As an unfavorable result, a modified joist section supported by Callahan&#39;s bracket may have a greater buckling tendency than the same modified joist section not supported by Callahan&#39;s bracket.  
      Another example for a reinforcement bracket is described in U.S. patent application Publication 2002/0121066 also to Callahan et al (2). There, the bracket of the above-described invention is modified to accommodate for material separations cut through the top chord of an I-joist. In general, the applicability of this device may be limited since material separations of the chords are highly questionable due to their tremendous negative effect on the joist&#39;s load carrying capacity. As is well-known in the art and dependent on the load carrying condition, building codes strictly mandate that transverse holes bored or cut into a joist must remain at a certain distance from the top or bottom of the joist. For an I-joist in particular, it is recommended by manufacturers to avoid cutting either of the cords of a load carrying I-joist section. In addition, the buckling increasing effect of the bracket becomes even more dominant where the remaining cross section of the modified I-joist is much thinner than the rectangular section of a conventional modified joist.  
      Also, in Callahan et al (2) the connection between the bracket and the I-joist relies substantially on screws or nails laterally attached to the remainder of the chords. Chords that are fabricated from vertically stacked, laminated wood are highly sensible to splicing initiated by horizontally attached nails or screws. Attaching a support device on the chords for the purpose of transmitting bending loads from the I-joist onto the bracket consequently may result in splicing of the chords. The splicing of the chords results in a further weakening of the modified I-joist section. The splicing also reduces the rigidity of connection between the bracket and the modified I-joist section. Therefore, there exists a need for a support structure that may be attached to a modified I-joist with reduced and/or without laterally attaching to the chord(s). The present invention addresses this need.  
      Prototype testing of the present invention has revealed that in addition to the buckling loads, significant shear loads are communicated between the I-joist&#39;s web and the reinforcement bracket. Shear loads become increasingly dominant with decreasing distance from the assembly location of the reinforcement bracket to the next I-joist bearing. The shear loads occur across the height of the web and need to be transferred between the web and the attached reinforcement bracket in a balanced fashion to avoid tearing out of attachment screws and/or other damage to the web at the assembly location. In addition, the reinforcement bracket needs to be configured for a gradual transfer of shear loads in span direction of the I-joist across an eventual web hole while covering the web hole as little as possible and while keeping stress peaks and stress gradients in the brackets structure at a minimum. At the same time, the reinforcement bracket needs to be light weight and simple to be attached to facilitate its use at construction sites. The present invention addresses also these needs.  
     SUMMARY  
      A support device for an I-joist provides buckling and shearing opposing support to the remaining web portions adjacent a hole erroneously cut into the I-joist&#39;s web. The buckling opposing support is established by bridging structures that protrude between and span across the top and bottom chords of the I-joist. The bridging structures are configured to provide a maximum bending resistance in a direction between the chords.  
      The support device is configured for a lateral attachment to an I-joist. The support device may be scaled and prefabricated in a number of configurations that correspond to dimensional standards of I-joists. Hence, by selecting a support device in a scale that corresponds to a dimensional standard of an I-joist at hand, a construction worker may easily repair an erroneously cut hole and or reinforce an I-joist&#39;s web portion by simply attaching the support device at an appropriate location.  
      In the preferred embodiment, the support device has an approximate U-shape such that it may be attached to the I-joist in a progressed construction assembly where other profile(s) is/are already assembled through the cut web hole.  
      The support device is preferably made of sheet metal and provides holes for readily attaching it to the web portion by nailing, screwing or other well-known fastening techniques feasible for attaching a sheet metal part to a wooden or wood like material. The support device further provides secondary holes for an eventual secondary attachment to the chord(s) for the purpose of adding rigidity to the assembled support device. Additional stiffening features may be part of the support device to either increase the device&#39;s stiffness against the web portions buckling tendency and/or to increase an interlocking and/or snuggly fit between the device and the I-joist. The bridging structures may further operate to transmit compressive forces eventually occurring between the chords as a result from the I-joists deflection. In that way, the buckling tendency of the web portion may be additionally opposed.  
      The support device or reinforcement bracket is configured for attachment and operation without substantially reducing the structural integrity and stress absorbing capability of the chords. Eventual attaching of the support device is provided in a fashion that keeps the chords&#39;splicing tendency to a minimum.  
      Shearing opposing support is provided by a shear load resistant interface in between the combined reinforcement bracket and spacing structure. The shear load is transferred between the web and the attached bridging structure across the height of the bridging structure, which is a multiple of the spacing structure&#39;s height. This results in an angular displacement of the attached bridging structure with respect to the spacing structure with stress peaks and maximum stress gradients in the interface and spacing structure. The interface has a configuration that assists in keeping stress peaks and stress gradients to a minimum. The interface configuration may include a transition radius between a width contour of the spacing structure and an adjacent height contour of the bridging structure. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       FIG. 1  shows an exemplary section view of a prior art assembly of representative first I-joists with a profile assembled in between.  
       FIG. 2  depicts the exemplary section view of  FIG. 1  with a support device in accordance with a first embodiment of the present invention attached at a central first I-joist.  
       FIG. 3  illustrates a first I-joist section with a support device in accordance with a first embodiment of the invention and a support structure attached in between.  
       FIG. 4  shows a section view of  FIG. 3  along a vertical plane approximately through a center of the support device.  
       FIG. 5  shows a vertical central section view of a first I-joist and a support device in accordance with a second embodiment of the invention.  
       FIG. 6  depicts a horizontal central section view of a first I-joist, the support structure of  FIG. 3  and a support device in accordance with a third embodiment of the invention.  
       FIG. 7  depicts a horizontal section view of a first I-joist and a first support device in accordance with a fourth embodiment of the invention. A second support device in accordance with the fourth embodiment is shown in attachment position opposing the first support device.  
       FIGS. 8A, 8B  depict a fifth embodiment in perspective view and in front view in protrusion direction of the first I-joist.  
       FIGS. 9A, 9B  depict a sixth embodiment in perspective view and in front view in protrusion direction of the I-joist. In  FIG. 9A , only a bottom portion of the first I-joist is shown with the web portion broken apart to free the view onto the entire support device.  
       FIGS. 10A, 10B  depict a seventh embodiment in perspective view and in front view in protrusion direction of the first I-joist. In  FIG. 10A , only a bottom portion of the first I-joist is shown with the web portion broken apart to free the view onto the entire support device.  
       FIGS. 11A-11D  illustrate various views of the support device in accordance with the first embodiment of the invention.  
       FIGS. 12A-12D  illustrate various views of the support device in accordance with the second embodiment of the invention.  
       FIGS. 13A-13D  illustrate various views of the support device in accordance with the third embodiment of the invention.  
       FIGS. 14A-14D  illustrate various views of the support device in accordance with the fourth embodiment of the invention.  
       FIGS. 15A-15D  illustrate various views of the support device in accordance with the fifth embodiment of the invention.  
       FIGS. 16A-16D  illustrate various views of the support device in accordance with the sixth embodiment of the invention.  
       FIGS. 17A-17D  illustrate various views of the support device in accordance with the seventh embodiment of the invention.  
       FIGS. 18A-18D  illustrate various views of the support device in accordance with the eighth embodiment of the invention.  
       FIGS. 19A-19D  illustrate various views of the support device in accordance with the ninth embodiment of the invention.  
       FIGS. 20A-20D  illustrate various views of the support device in accordance with the tenth embodiment of the invention.  
       FIGS. 21A-21D  illustrate various views of the support device in accordance with the eleventh embodiment of the invention.  
       FIG. 22  is a perspective view of a reinforcement bracket of a twelfth embodiment attached to a representative second ljoist.  
       FIG. 23  is a perspective view of a preferred thirteenth embodiment of the invention.  
       FIG. 24  is a perspective view of a representative third I-joist having an erroneously cut hole and the reinforcement bracket of  FIG. 23  assembled at the erroneously cut hole.  
       FIG. 25  is a color plot of a representative stress analysis of a portion of the third I-joist without erroneously cut hole, the portion being approximately within frame AJ of  FIG. 23 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 26, 32 ,  33 ,  35 ,  36 ,  38 ,  39 ,  41 ,  42 .  
       FIG. 26  is a color plot of a representative stress analysis of a portion of the third I-joist, the portion being approximately within frame AJ of  FIG. 23 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 32 ,  33 ,  35 ,  36 ,  38 ,  39 ,  41 ,  42 .  
       FIG. 27  is a color plot of a representative displacement analysis of a portion of the third I-joist with assembled reinforcement bracket of  FIG. 23 , the portion being approximately within frame AJ of  FIG. 24 . The Figure depicts isolated up scaled displacement in direction along the I-joist length corresponding to shear displacement of the I-joist and its deforming influence on the assembled reinforcement bracket of  FIG. 23 . The color coding in the Figure corresponds to the displacement color scale of  FIG. 29 .  
       FIG. 28  is a stress color scale with medium blue corresponding to a minimum stress and red corresponding to a maximum stress.  
       FIG. 29  is a displacement color scale with maximum compressive displacement corresponding to dark blue and maximum tensile displacement corresponding to red.  
       FIG. 30  is a front view color plot approximately within frame AJ of  FIG. 24  of a representative stress analysis of the reinforcement brackets of  FIG. 22  assembled by attachment via attachment holes  212  on the third I-joist. The attachment at the attachment holes  212  is considered substantially rigid such that rotational web displacement resulting from the shear displacement in the vicinity of the attachment holes  212  is transmitted onto the attachment holes  212  and the surrounding structure of the reinforcement bracket. The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 31, 34 ,  37 ,  40 .  
       FIG. 31  is a back view of the color plot of  FIG. 30 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 30, 34 ,  37 ,  40 .  
       FIG. 32  is a front view color plot of a representative stress analysis of a portion of the first I-joist with assembled and attached reinforcement brackets of  FIG. 22 , the portion being approximately within frame AJ of  FIG. 24 . The attachment condition corresponds to that of  FIGS. 30, 31 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  33 ,  35 ,  36 ,  38 ,  39 ,  41 ,  42 .  
       FIG. 33  is a back view of the color plot of  FIG. 32 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  32 ,  35 ,  36 ,  38 ,  39 , 41 ,  42 .  
       FIG. 34  is a color plot approximately within frame AR of  FIG. 24  of a representative stress analysis of the reinforcement bracket of  FIG. 23  assembled by attachment via attachment holes  212  on the third I-joist. The attachment at the attachment holes  212  is considered substantially free of friction such that rotational web displacement resulting from the shear displacement in the vicinity of the attachment holes  212  is not transmitted onto the attachment holes  212  and the surrounding structure of the reinforcement bracket. The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 30, 31 ,  37 ,  40 .  
       FIG. 35  is a front view color plot of a representative stress analysis of a portion of the third I-joist with assembled and attached reinforcement bracket of  FIG. 23 , the portion being approximately within frame AJ of  FIG. 24 . The attachment condition corresponds to that of  FIG. 34 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  32 ,  33 ,  36 ,  38 ,  39 ,  41 ,  42 .  
       FIG. 36  is a back view of the color plot of  FIG. 35 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  32 ,  33 ,  35 ,  38 ,  39 ,  41 ,  42 .  
       FIG. 37  is a color plot approximately within frame AR of  FIG. 24  of a representative stress analysis of the reinforcement bracket of  FIG. 23  assembled by attachment via attachment holes  212  on the third lioist. The attachment at the attachment holes  212  is considered rigid such that rotational web displacement resulting from the shear displacement in the vicinity of the attachment holes  212  is transmitted onto the attachment holes  212  and the surrounding structure of the reinforcement bracket. The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 30, 31 ,  35 ,  40 .  
       FIG. 38  is a front view color plot of a representative stress analysis of a portion of the third I-joist with assembled and attached reinforcement bracket of  FIG. 23 , the portion being approximately within frame AJ of  FIG. 24 . The attachment condition corresponds to that of  FIG. 37 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  32 ,  33 ,  36 ,  36 ,  39 ,  41 ,  42 .  
       FIG. 39  is a back view of the color plot of  FIG. 38 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  32 ,  33 ,  35 ,  36 ,  38 ,  41 ,  42 .  
       FIG. 40  is a color plot approximately within frame AR of  FIG. 24  of a representative stress analysis of the reinforcement bracket of  FIG. 23  assembled by attachment via attachment holes  212  and  221  on the third I-joist. The attachment at the attachment holes  212  and  221  is considered rigid. Rotational web displacement from the shear displacement in the vicinity of the attachment holes  212  is transmitted onto the attachment holes  212  and the surrounding structure of the reinforcement bracket. The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 30, 31 ,  35 ,  37 .  
       FIG. 41  is a front view color plot of a representative stress analysis of a portion of the third I-joist with assembled and attached reinforcement bracket of  FIG. 23 , the portion being approximately within frame AJ of  FIG. 24 . The attachment condition corresponds to that of  FIG. 40 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  32 ,  33 ,  35 ,  36 ,  38 ,  39 ,  42 .  
       FIG. 42  is a back view of the color plot of  FIG. 41 . The color coding in the Figure corresponds to the stress color scale of  FIG. 28  and is equalized in its color-stress correspondence with  FIGS. 25, 26 ,  32 ,  33 ,  35 ,  36 ,  38 ,  39 ,  41 . 
    
    
     DETAILED DESCRIPTION  
      Prior art  FIG. 1  shows exemplary sections of first I-joists  1  assembled as it may occur in architectural constructions. There, holes  15  may be cut into the I-joists&#39;  1  central web portions  3  such that a profile  18  may be installed in between the top chord  4  and the bottom chord  2  in directions other than parallel to the I-joists  1 . The profile  18  may be an electrical line, a plumbing pipe or the like.  
      To reduce a buckling tendency of the modified I-joist  1 , manufacturers provide dimensional safety limits for holes  15  cut into I-joist  1 . These safety limits may not be met by the construction workers, which are typically in charge of fabricating the holes  15  at the construction site. A buckling tendency of the web  3  may become unpredictable and excessive where the hole  15  exceeds the safety limits.  
      With respect to the present invention, the first, second and third I-joists  1 ,  1 B,  1 C (see also  FIGS. 22, 24 ) are I-shaped profiles made from wooden and/or wood like material. I-joists  1 ,  1 B,  1 C may be provided by manufacturers in a number of dimensional standards, which include a chord width  7 , a total height  5 , a chord height  10 , a web thickness  9  and web height  8 . I-joists  1 ,  1 B,  1 C may be preferably symmetric with respect to a horizontal and a vertical center plane of the I-joist  1 ,  1 B,  1 C as is well appreciated by anyone skilled in the art. The symmetric shape provides for a symmetric section modulus that keeps a buckling tendency to a minimum in unmodified condition of the I-joists  1 ,  1 B,  1 C in general and the web  3  in particular.  
      Additional elements like, for example a profile  18  may extend through the web portions  3  of adjacent I-joists  1 , 1 B,  1 C. The exemplary profile  18  may be an electrical line, a plumbing pipe or the like. To install the profile  18  at the construction site, holes  15  are cut into the I-joists  1 ,  1 B,  1 C.  
      Holes  15  may be cut in accordance with maximum safety dimensions established by manufacturers for their respective I-joist products. The maximum safety dimensions may include a maximum allowable hole diameter  16 , a minimum remaining web height  6  adjacent the top cord  4  andlor the bottom chord  2 . The maximum safety dimensions are exemplary illustrated as a dot dashed line.  
      Holes  15  may exceed the maximum safety dimensions, which results in an unpredictable buckling tendency of the remaining web portion  3  adjacent the erroneously cut hole  15 . As illustrated in  FIG. 2 , a support device or reinforcement bracket  100  may be laterally attached to the I-joist I having an erroneously cut hole  15 . The support device  100  is primarily attached to the web portion  3  via an additional support structure  20 .  
      The support device  100  provides bridging structures  110  that spans across the web height  8  with its central portion. The bridging structures  110  has a buckling opposing configuration along their respective bridging height  210 H (see  FIGS. 22, 23 ) and establish with their central portion a buckling opposing interface with the web  3  once attached to the web  3 . By placing a bridging structure  110  of the first embodiment immediately adjacent the erroneously cut hole  15  and combining it with the additional support structure  20 , the unpredictable buckling tendency of the I-joist  1  in the vicinity of the erroneously cut hole  15  is brought within predictable limits.  
      In the context of the present invention the terms “top”, “bottom”, “horizontal”, “vertical”, “height”,“width” are introduced in reference to an assembly position of the support device  100  on an I-joist  1 ,  1 B,  1 C in a conventional assembly position with one chord above the other, where the I-joist  1 ,  1 B,  1 C may have its maximum load carrying capacity.  
      A buckling opposing interface is defined by contacting the remainder of the web  3  with the central portion of the bridging structure  110  that is provided with a bending stiffness at a level such that the buckling tendency of the remaining web  3  is kept equal or below to a reference buckling value associated with the maximum safety dimensions. The buckling opposing interface may be preferably established by fastening the central portion to the remaining web  3 .  
      The support device  100  is scaled in conjunction with the dimensional standards of the I-joists  1 . Hence, by merely selecting the properly scaled support device  100 , a hole  15  erroneously cut in any standard I-joist  1  may be easily repaired.  
      The erroneously cut hole  15  is preferably flanked on both sides by a bridging structure  110 . To accommodate for the preferred dual application of two flanking bridging structures  110 , the present invention has a preferred configuration as an approximately U-shaped device in which two bridging structures  110  are combined by a chord embedding structure  120 . The chord embedding structure  120  is configured to snugly fit over a lateral portion of preferably one of the chords  2 ,  4 . In that way, the support device  100  may be easily brought into assembly position by pushing the cord embedding structure  120  onto one of the chords  2 ,  4 . The support device&#39;s  100  U-shape provides for an access to the assembly location regardless the eventual presence of profile  18  protruding through the I-joists  1 ,  1 B,  1 C.  
      The scope of the invention is not limited to a particular number, orientation and/or spacing of the bridging structures  110  to each other. Nevertheless, in the preferred embodiment of the invention, the bridging structures  110  are preferably parallel to each other and are substantially perpendicular oriented with respect to the chord embedding structure  120 . Thus, once the support device  100  is attached to the I-joist  1 , the bridging structures  110  are substantially perpendicular to the protrusion direction of the I-joist  1 ,  1 B,  1 C. As another result, a low overall width  102  of the support device  100  is assured for a given clearance distance  101 . The clearance distance  101  may be selected in accordance with the maximum allowable hole diameter  16 .  
      In the first, second, third and fourth embodiments of the invention described in the above and the below and as is shown in  FIG. 3 , each bridging structure  110  is a profile that extends substantially perpendicular to the I-joist&#39;s  1  protrusion direction in assembly position. End portions  111  of the bridging structures  110  continue and extend across the lateral portions of the chords  2 ,  4 . The end portions  111  may be attached to the chords  2 ,  4  via secondary holes  121  primarily for the purpose of adding rigidity to the assembled support device  100 .  
      Particularly, the secondary holes  121  may be configured in size and number to keep a splicing risk of the chords  2 ,  4  to a minimum.  
      The central portion of the bridging structures  110  feature primary attachment holes  112 . Holes  112 ,  121  are configured for receiving fasteners well known for architectural constructions. Such fasteners may include but are not limited to nails, screws and the like. The holes may be substituted by indentations such that a nail or screw is initially forced through solid material of the support device  100 .  
      In the first embodiment, the bridging structure  110  is configured for including an additional support structure  20  in the buckling opposing interface. The primary holes  112  serve thereby for attaching the central portion to the support structure  20  via well known fasteners such as nails, screws and the like. The support structure  20  may be a piece of rectangular wood with a cross section corresponding to a gap between the central bridge portion and the web  3 .  
      The support device  100  is preferably monolithically made of sheet metal, which assures minimum increase of the I-joist&#39;s  1  overall width  7 . As a primary means for stiffening the support device  100 , a first stiffening rib  130  is provided along the inside contour of the support device  100 . The first stiffening rib  130  protrudes substantially perpendicular with respect to a reference plane  11 . The reference plane  11  is substantially parallel to the main planar body of the support device  100  in assembly position. The reference plane  11  is defined by correspondingly opposing lateral edges of the chords  2 ,  4  at the same side of the I-joist  1 . In context with the present invention, the term side of the I-joist  1  refers to either a left or a right side of the I-joist  1  in the protrusion direction of the I-joist  1  and with the I-joist  1  being oriented with the chord  4  being on top of the chord  2 .  
      The main planar body is a substantially flat portion of the support device  100  including the flat portion of the bridging structures  110  and the flat portion of the chord embedding structure  120 . The first stiffening rib  130  has a height that corresponds to the half of the difference between chord width  7  and web thickness  9  such that the top edge of the first stiffening rib  130  snugly contacts the web  3  when the support device  100  is attached to the I-joist  1 ,  1 B,  1 C. A horizontal portion of the first stiffening rib  130  is positioned on the support device  100  such that in assembled position of the support device  100  the first rib&#39;s  130  horizontal portion contacts a lateral portion of one of the chords  2 ,  4  inside the I-joist  1 .  
      As shown in  FIGS. 4 and 5 , the support device  100  may also feature a second stiffening rib  140  that protrudes in direction substantially parallel to the first stiffening rib  130  from the bottom edge of the chord embedding structure  120 . The second stiffening rib  140  and the horizontal portion of the first stiffening rib  130  are in a distance substantially equal to the chord height  10 . The second stiffening rib  130  is positioned on the support device  100  such that in assembled position of the support device  100  the second stiffening rib  140  contacts the lateral portion of one of the chords  2 ,  4  outside the I-joist  1 .  
      The first rib&#39;s  130  horizontal portion and the second rib  140  provide for an intermediate reliable positioning of the support device  100  in its final assembly position such that the support device  100  may be temporarily held in assembly position by merely pushing the support device  100  with its chord embedding structure  120  over a lateral portion of a chord  2  or  4 . This is particularly advantageous where the support device  100  needs to be assembled at locations that are difficult to access by a construction worker. A support device  100  in accordance with the first embodiment is shown in top view in  FIG. 11A , in perspective view in  FIG. 11B , in side view in  FIG. 11C , which is in protrusion direction of the I-joist  1 ,  1 B, IC, and in front view in  FIG. 11D , which is in direction of the reference plane  11 .  
      In  FIG. 5 , a second embodiment is illustrated in which the first stiffening rib  130  features a first flange  132 , which on one hand increases the stiffness of the first stiffening rib  130  and on the other hand provides for an area contact between the first stiffening rib  130  and the web  3 . A support device  100  in accordance with the second embodiment is shown in top view in  FIG. 12A , in perspective view in  FIG. 12B , in side view in  FIG. 12C , which is in protrusion direction of the I-joist  1 , and in front view in  FIG. 12D , which is in direction of the reference plane  11 .  
      In  FIG. 6 , a third of the preferred embodiments is illustrated, in which third stiffening ribs  150  protrude from the outer edge of one or both of the bridging structures  110 . The third stiffening ribs  150  protrude in direction substantially parallel to the first stiffening rib  130  and may be of substantially equal height as the first stiffening rib  130 . The third stiffening ribs  150  provide additional bending stiffness to the central portion of the bridging structures  110 . The third stiffening ribs  150  may be in a distance to a vertical portion of the first stiffening rib  130  such that the support structure  20  may be snugly held between them. This may additionally ease the assembly process, since the support structure  20  may be brought into position relative to the support device  100  prior to assembly of the support device  100  itself. A support device  100  in accordance with the third embodiment is shown in top view in  FIG. 13A , in perspective view in  FIG. 13B , in side view in  FIG. 13C , which is in protrusion direction of the I-joist  1 , and in front view in  FIG. 13D , which is in direction of the reference plane  11 .  
      In  FIG. 7 , a fourth of the preferred embodiments is illustrated in which the third stiffening ribs  150  feature second flanges  152 , which on one hand increase the stiffness of the third stiffening rib  150  and on the other hand provide for an additional area contact between the third stiffening ribs  150  and the web  3 .  FIG. 7  shows an additional support device  100  of the fourth embodiment in a second assembly position on the opposite side of the web  3 . In that fashion maximum buckling opposing support may be provided from both sides to the web  3 . Opposing contact pressure in the buckling opposing interfaces holds thereby the web  3 . The opposing contact pressure may be applied by fasteners holding together two opposing flanges  132  and/or  152  through the web  3 . The dual assembly position of  FIG. 7  is not limited to a particular embodiment of the support structure  100 . A support device  100  in accordance with the fourth embodiment is shown in top view in  FIG. 14A , in perspective view in  FIG. 14B , in side view in  FIG. 14C , which is in protrusion direction of the I-joist  1   1   b ,  1 C, and in front view in  FIG. 14D , which is in direction of the reference plane  11 . The flanges  132  and  152  may also feature primary attachment holes  112  for a direct attachment to the web  3 .  
      In the first, second, third and fourth embodiments, the main planar body of the support device 100 is placed immediately adjacent the reference plane  11 . The stiffening ribs  130 ,  140 ,  150  point towards the web  3  in assembled position. The buckling opposing interface is defined either by attachment of the bridging structures&#39;  110  planar portions to the web  3  via the support structure  20  and/or by attachment of the flanges  132  and/or  152  to the web  3 .  
      In the remaining fifth, sixth, seventh, eights, ninth, tenth, eleventh, twelfth and thirteenth embodiments described in the below under  FIGS. 8-10  and  FIGS. 15-24  the support device  200  is configured for a direct contact of the main planar body portion with the web  3 . In assembly position of the support device  200 , the stiffening ribs  230 ,  240 ,  250 ,  260 ,  270  protrude away from the web  3 . The buckling opposing interface is defined primarily by attachment of the bridging structures&#39;  110  planar portions directly to the web  3 .  
      Whereas the first, second, third and fourth embodiments are configured for preferably including the support structure  20 , the remaining embodiments are specifically configured to provide a buckling opposing interface without use of the additional support structure  20 . The remaining embodiments provide for a splicing opposing connection of the support device  200  in a corner line  12  along a boundary between web  3  and either of the chords  2 ,  4 .  
      The fifth embodiment of the invention is shown in assembled position in  FIGS. 8A and 8B . The main planar body of the support device  200  contacts one side of the web  3  along the web height  8 . A horizontally oriented spacing structure  220  combines and holds the two bridging structures  210  in a predetermined clearance distance as is described for the first, second, third and fourth embodiments. Primary attachment holes  212  are placed along the protrusion direction of the bridging structures  212  for a direct attachment of the bridging structures  212  to the web  3 .  
      A fourth primary stiffening rib  240  spans across the two bridging structures  210 . The fourth primary stiffening rib  240  may be interrupted or continuous as is exemplarily depicted in the Figures. The fourth primary stiffening rib  240  is substantially perpendicular to the main planar body. The fourth primary stiffening rib  240  s positioned on the support device  200  such that it snugly contacts in assembly position the lateral inside portion of at least one of the chords  2 ,  4 , while the bridging structures  210  are oriented across the web  3 .  
      The support device  200  further features angulated holes  221  protruding through and positioned in a fold between the main planar body and the fourth primary stiffening rib  240 . In that way, the said support device  200  may be attached with fastener  300  along an angle  222  through the angulated holes  221  to the I-joist  1 ,  1 B,  1 C. In assembled position where the main planar body snugly contacts the web  3  and where the fourth primary stiffening rib  240  snugly contacts the inside of one of the chords  2 ,  4 , the angulated holes  221  point directly onto a corner line  12 . Corner lines  12  exist along the boundaries between the web  3  and the chords  2 ,  4 .  
      The corner line  12  provides thereby for a centering of the fasteners  300  avoiding a slipping of them along a surface of the I-joist  1 ,  1 B,  1 C prior to surface penetration. In addition, the angular penetration of the fasteners  300  along the corner line  12  keeps a splicing risk of the chord(s)  2 ,  4  to a minimum. Also, the angular fastening direction provides for an easy access of the fasteners during their placement.  
      Further, the angular fastening direction provides for a simultaneous contact pressure of the main planar body and the fourth primary stiffening rib  240  with the opposing surfaces of the I-joist  1 ,  1 B,  1 C. Hence, by initially attaching the support device  200  on the I-joist  1 ,  1 B,  1 C via the fasteners  300  and through the angular holes  221 , the support device is brought into a tight, snug contact position with both the web  3  and one the bottom chord  2 . In case the support device  200  is attached with the spacing structure  220  above the hole  15 , the fourth stiffening  240  snugly contacts the top chord  4 .  
      The bridging structures  210  are directly attached to the web  3  via primary attachment holes  212 . The bridging structures  210  operate similar like bridging structures  110  except that they provide the buckling opposing interface with the remainder of the web  3  without inclusion of the support structure  20 . A support device  200  in accordance with the fifth embodiment is shown in top view in  FIG. 15A , in perspective view in  FIG. 15B , in side view in  FIG. 15C , which is in protrusion direction of the I-joist  1 ,  1 B,  1 C, and in front view in  FIG. 15D , which is in direction of the reference plane  11 .  
       FIGS. 9A and 9B  illustrate a sixth embodiment in which secondary fourth stiffening ribs  241  span across the bridging structures  210  opposite the fourth primary stiffening rib  240 . Angular holes  223  protrude through the fold between secondary fourth stiffening rib  241  and the bridging structures  210  in an angle  224 . Fasteners  301  may be attached in a fashion similar as described in the above for the angular holes  221  and the fasteners  300 .  
      A height of the support device  200  is selected in correspondence with varying dimensional standards of the web height  8 . Consequently, fourth stiffening ribs  240 ,  241  nugly contact both chords  2 ,  4  and provide for a direct transmission of an eventual compressive force between the chords  2 ,  4  resulting from a load carrying deflection of the I-joist  1 ,  1 B,  1 C. The web  3  may be consequently supported and/or relieved from compressive peak loads, which additionally reduces the web&#39;s  3  buckling tendency. A support device  200  in accordance with the sixth embodiment is shown in top view in  FIG. 16A , in perspective view in  FIG. 168 , in side view in  FIG. 16C , which is in protrusion direction of the I-joist  1 ,  1 B,  1 C, and in front view in  FIG. 16D , which is in direction of the reference plane  11 .  
       Figs. 10A and 10B  show a seventh embodiment in which a fifth stiffening rib  230  protrudes along the inside U-shaped edge of the support device  200 . The fifth stiffening rib  230  protrudes perpendicular from the main planar body in direction of either of the fourth stiffening ribs  240 ,  241 . In case, the support device  200  features a fourth secondary stiffening rib  241 , the fifth stiffening rib  230  may be fully, partially or not directly connected to the rib  241 . The fifth stiffening rib  230  may have flaps extending at its ends (not shown). The flaps may be bent into an orientation parallel to the rib(s)  240  as is well known for enforcing three plane-corner regions of folded sheet metal parts.  
      An offset  231  between the horizontal portion of the fifth stiffening rib  230  and the fourth primary rib  240  may correspond to the chord height  10 . In that fashion, the support device  200  may be assembled with the main planar body being coplanar to the reference plane  11  and with the stiffening ribs  230 ,  240  or  241  pointing towards the web  3 ; the spacing structure  220  may operate thereby similar to the chord embedding structure  120 . A support device  200  in accordance with the seventh embodiment is shown in top view in  FIG. 17A , in perspective view in  FIG. 17B , in side view in  FIG. 17C , which is in protrusion direction of the I-joist  1 ,  1 B,  1 C, and in front view in  FIG. 17D , which is in direction of the reference plane  11 .  
      A support device  200  in accordance with an eight embodiment is shown in top view in  FIG. 18A , in perspective view in  FIG. 18B , in side view in  FIG. 18C , which is in protrusion direction of the I-joist  1 ,  1 B,  1 C, and in front view in  FIG. 18D , which is in direction of the reference plane  11 . In the eight embodiment, the support device  200  features sixth stiffening ribs  250  that protrude from the outside edges of the bridging structures  210  perpendicular from the main planar body in direction of either of the fourth stiffening ribs  240 ,  241 . The sixth stiffening ribs  250  may be fully, partially or not connected to either or both of the stiffening ribs  240 ,  241 . The sixth stiffening ribs  250  may have flaps extending at either or both of its ends. The flaps may be bent into an orientation parallel to the rib(s)  240 ,  241  as is well known for enforcing three-plane corner regions of folded sheet metal parts.  
      A support device  200  in accordance with a ninth embodiment is shown in top view in  FIG. 19A , in perspective view in  FIG. 19B , in side view in  FIG. 19C , which is in protrusion direction of the I-joist  1 ,  1 B,  1 C, and in front view in  FIG. 19D , which is in direction of the reference plane  11 . In the ninth embodiment, the fourth stiffening ribs  240 ,  241  include a back folded support angle featuring first wings  243 ,  245  and second wings  244 ,  246 . First wings  243 ,  245  are continuations of the fourth stiffening ribs  240 ,  241  that are bent backwards at their peripheral ends and brought into substantially parallel orientation. The second wings  244 ,  246  are parallel to the main planar body. The angulated holes  221 ,  223  protrude all the way through the support angles. The support angles substantially increase a bending stiffness of said fourth stiffening ribs  240 ,  241  as may be well appreciated by anyone skilled in the art.  
      A support device  200  in accordance with a tenth embodiment is shown in top view in  FIG. 20A , in perspective view in  FIG. 20B , in side view in  FIG. 20C , which is in protrusion direction of the I-joist  1 ,  1 B,  1 C, and in front view in  FIG. 20D , which is in direction of the reference plane  11 . In the tenth embodiment, the fourth stiffening ribs  240 ,  241  feature at their peripheral ends stiffening flanges  242 ,  247 . Similarly, fifth and sixth stiffening ribs  230 ,  250  may also feature stiffening flanges (not shown). The stiffening flanges  242 ,  247  provide additional buckling stiffness to the ribs from which they extend.  
      Also, the stiffening flanges  242 ,  247  may be bent opposite to the direction indicated in the  FIGS. 20A-20D . In that fashion, the stiffening flanges  242 ,  247  may wrap around the chord(s)  2 ,  4 . Eventual additional flanges (not shown) may be provided at the peripheral ends of the stiffening flanges  242 ,  247  such that the chord(s)  2 ,  4  islare embraced from three sides by sheet metal.  
      Finally, a support device  200  in accordance with an eleventh embodiment is shown in top view in  FIG. 21A , in perspective view in  FIG. 21B , in side view in  FIG. 21C , which is in protrusion direction of the I-joist  1 ,  1 B,  1 C, and in front view in  FIG. 21D , which is in direction of the reference plane  11 . In the eleventh embodiment, the support device  200  features seventh stiffening ribs  260 ,  270  indented in the main planar body.  
      A practical test of a wooden I-joist, commercially available under the specification 9½″ LPI  200  with a maximal shear load or nominal load of 1125 lb under standardized conditions was reinforced by a single support device  200  according to the seventh embodiment made from 16 gage standard sheet metal. A hole was cut into the web portion of the tested I-joist. The cut hole extended in vertical direction from top chord to bottom chord and in horizontal direction from side to side up to the vertical portions of the inside U-shaped contour of the support device  200 . The practical test resulted in tested failure load of 2370 lb, which corresponds to a maximum allowable shear load of 790 lb after applying a safety factor of 3 as is well known in the art. This is about 70% of the nominal load. Testing conditions complied with standards established by the World I-joist Manufacturer Association (WIJMA) for shear load testing of I-joists with web holes as is well known in the art.  
      The support devices  100 ,  200  are preferably fabricated from sheet metal by bending, deep drawing, hydro forming and/or other well-known sheet metal forming operations.  
      The scope of the invention includes embodiments in which the two bridging structures  110  are combined by two opposing chord embedding structures  120  and/or in which the two bridging structures  210  are combined by two opposing spacing structures  220 . In that cases, the outside contour of the support devices  100 ,  200  in view onto the reference plane  11  is approximately that of a square. The inside contour has thereby an approximately O-shape. In that cases, stiffening ribs  130 ,  230  follow the O-shape contour.  
      The scope of the invention includes embodiments, in which more than two bridging structures  110 ,  210  are combined by alternately arrayed structures  120 ,  220 .  
      The support device  100  may be provided as a repair means for erroneously cut holes  15 . The support device  100  may also be configured for providing a cutting mask to prevent erroneously hole cutting.  
      The support devices  100 ,  200  may be part of an originally fabricated I-joist  1 ,  1 B,  1 C for the purpose of providing increased buckling resistance and/or bending resistance at a given section of the I-joist  1 ,  1 B,  1 C. This may be particularly advantageous, where it is desirable to keep the all over dimensions of an I-joist  1 ,  1 B,  1 C to a minimum regardless an eventual peak load at identified sections of the I-joist  1 ,  1 B,  1 C.  
      Referring to  FIGS. 22-42 , additional findings and inventive steps of the present invention are described in the following. Characteristics unique for wooden I-joists  1 ,  1 B,  1 C include dissimilar stiffness properties of web  3  and chord  2 ,  4  material, which result in peaks of well known I-joist shear loads in the glue connection between the web spigots  33  and the chord grooves  21 ,  41  (see  FIG. 22 ). During additional testing this unique characteristic became apparent due to glue connection failure in more than 90% of the tests. Because at least of the above wooden I-joist  1 ,  1 B,  1 C characteristic the reinforcement bracket  200  is particularly suited for wooden I-joists  1 ,  1 B,  1 C as will be more apparent in the below.  
      Another characteristic of wooden I-joist  1 ,  1 B,  1 C as described further above is the splicing tendency of its chords  2 ,  4 , which is addressed by the angulated attachment holes  221  along the overall width  202 . The attachment angle  222  of the angulated holes  221  is preferably smaller than spigot taper angle  332  such that the fasteners  300  mainly penetrate web  3  material extending via the spigots  33  into grooves  21 ,  41  of the chords  2 ,  4  while the reinforcement bracket  200  is attached to the wooden I-joist  1 ,  1 B,  1 C via the angulated holes  221  in a corner line along the boundary between the web  3  and one of the cords  2 ,  4 . The attachment angle  222  is a symmetry angle between planar body and fourth stiffening rib  240  such that the fasteners  300  apply a balanced tightening force via their respective heads once the fasteners  300  are tightened. For a preferred perpendicularly protruding fourth stiffening rib  240  the attachment angle  222  is about 45 degree. The spigot taper angle  332  is conventionally larger than 60 degrees.  
      The additional testing of reinforcement bracket  200  in combination with a variety of brands of wooden I-joists  1 ,  1 B,  1 C, commercially available under the brand names Trus Joist™, APA™, Lousiana Pacific™, Boise™ in standardized total heights 5 of 9½ inches, 11⅞ inches, 14 inches and 16 inches revealed for increasing total heights  5  and decreasing bearing distance  17 L (see  FIG. 24 ) increasing contour stress peaks and stress gradients particularly in an interface  290  (see  FIGS. 22, 23 ) between the bridging structure  210  and the spacing structure  220 . Contour stress peaks and stress gradients increase together with I-joist shear load communicated onto the bridging structure  210  across the bridging height  210 H in dependence on the rigidity of the bridging structure&#39;s  210  attachment to the web  3 . It was discovered that the communicated shear load resulted particularly in an angular displacement between the bridging structure  210  and the spacing structure  220  as is illustrated in  FIG. 27 . To oppose the shear load while flattening stress gradients and minimizing contour stress peaks, the interface  290  was stiffened by adding a transition radius  290 R of at least about half the bridging height  210 H. The transition radius  290 R is placed between a first width contour  229  of the spacing structure  220  and an adjacent height contour  219  of the bridging structure  210 . First width contour  229  and adjacent height contour  219  are introduced in this application for the purpose of unambiguously locating the transition radius  290 R and a contour recess described in the below. It is clear to anyone skilled in the art that the transition radius  290 R may have a dimension such that first width contour  229  and/or adjacent height contour  219  are of zero length.  
      The stiffening configuration of the interface  290  may also include a curved rib island  271  in an approximately concentric offset to the transition radius  290 R, which assists in flattening the contour stress gradient away from the transition radius  290 R as can be seen in  FIGS. 34, 37 ,  40 . The curved rib island  271  assists also in opposing secondary buckling forces resulting from the stress peaks and stress gradients in the planar sheet metal body of the interface  290  as may be well appreciated by anyone skilled in the art. The curved rib island  271  is particularly feasible in case of the reinforcement bracket  200  being made of sheet metal.  
      The bridging structure  210  has a bridging height  210 H and a bridging width  210 W within which an attachment face  218  is facing in direction opposite the protrusion direction of the ribs  230 ,  240 ,  250 . The attachment holes  212  are arrayed within the attachment face  218  such that contact pressure from fasteners tightened through the attachment holes  212  on the web  3  provide a contact pressure between the attachment face  218  and the web  3  in a balanced fashion.  
      The resulting contact friction between the attachment face  218  and the web  3  assists in conjunction with the attachment hole fasteners in transferring shear loads between the web  3  the buckling structure  210 . The bridging structure  210  has a buckling opposing configuration in direction  
      The bridging structure  210  has a buckling opposing configuration in direction along its bridging height  210  reinforcing the web  3  at the attachment location of the bridging structure  210 . In case of the reinforcement bracket  200  being made of sheet metal, the buckling opposing configuration indudes sixth stiffening rib  260  and/or a central bridging rib island  261 .  
      The spacing structure  220  has a spacing height  220 H and a spacing width  220 W. The spacing height  220 H is a fraction of the bridging height  210 H and the spacing width is a multiple of the bridging width  210 W. The spacing width  220 W is preferably larger than the bridging height  210 H. The overall width  202  of the reinforcement bracket  200  includes the spacing width  220 W and the bridging width  210 W.  
      Referring to  FIGS. 23, 24 , preferably two bridging structures  210  are angularly combined oppositely the spacing structure  210  such that the spacing structure  210  extends with its spacing width  220 W between the adjacent height contours  219 . A contour recess having a clearance width  201  and a recess height  203  is thereby defined between the adjacent height contours  219 , the first spacing width contour  229  and the transition radii  290 R.  
      The reinforcement bracket  200  of  FIGS. 23, 24  is preferably monolithically made of sheet metal having a thickness of 16 gage respectively about 1.5 mm in approximate dimensional ranges listed in Table 1 below. The reinforcement brackets  200  of Table 1 are preferably attached to wooden I-joist having a height  5 , a web hole  15  of up to modified boundary circle  17 D down to a bearing distance  17 L listed in Table 1 adjacent the respective reinforcement bracket  200  dimensions. Fasteners  300  and fasteners for attaching the bridging structures  210  preferably conform to ANSI Specification B18.6.4-1981. Heights of ribs  230 ,  240 ,  250 ,  261 ,  271  are about 0.5 inches. Dimensions of Table 1 are approximate inches dimensions.  
                                               TABLE 1                       Bridging   Overall   Bridging   Transition   Clearance   Recess   I-joist   Boundary   Bearing       height   width   width   radius   distance   Height   height   diameter   distance       210H   202   210W   290R   201   203   5   17D   17L                                                                    6.4   15.1   3.6   3.3   7.9   4.7   9.5   6   18       8.8   17.6   3.6   4.5   10.4   6.6   11.5   8.4   18       10.9   19.6   3.6   5.5   12.4   9.2   14   10.5   18       12.9   21.6   3.6   6.5   14.4   11.2   16   12.5   18                  
 
      In case the reinforcement bracket  200  is made of sheet metal, the fifth stiffening rib  230  protruding along the first width contour  229 , the transition radius or radii  290 R and the adjacent height contour(s)  219  assists in increasing buckling opposing strength of the bridging structure  210 . The fifth stiffening rib  230  assists also in increasing shearing opposing strength of the interface  290  and secondary buckling opposing strength of the interface  290  and the spacing structure  210 . Secondary buckling may result from the shear loads exerted onto the interface structure  290  and spacing structure  210 . The fourth stiffening rib  240  and curved rib island  271  may also strengthen the interface  290  and the spacing structure  210  against secondary buckling. Due to the substantially perpendicular rib protrusion of the rib islands  261 ,  271 , bridging structure  210  and interface  290  are significantly strengthened against buckling compared with further above described indented ribs  260 ,  270 . The fourth stiffening rib  240  may also provide stiffness against a tertiary buckling of an adjacent chord  2 ,  4  under compressive load.  
      Reinforcement brackets  200  may be attached at a web hole  17  on both sides of the web  3  as depicted in  FIG. 22  such that the attachment faces  218  are facing each other. In the more particular case, where the reinforcement brackets  200  are oppositely attached such that their respective outside contours are substantially collinear in direction perpendicular to their attachment faces  218 , spacing holes  213  may be alternately inter arrayed with the attachment holes  212 , such that attachment holes  212  of a first of the opposing reinforcement brackets  200  face a spacing hole of a second of the opposing reinforcement brackets  200 . In that way, fasteners penetrating through the attachment holes  212  and the web  3  are prevented from pushing the opposing attachment face  218  away. In that way the full web width  9  may be utilized in combination with the fasteners&#39;in thread, while a well known conical Up portion of the fastener may emerge unimpeded by the opposite reinforcement bracket  200 . The conical tip portion is necessary for the fastener to bite into the solid web  3  as is well known in the art for a maximum connection strength between web  3  and bridging structure  210 .  
      Also in conjunction with oppositely aligned reinforcement brackets  200  attached with their angulated holes adjacent a single chord  2  or  4 , the angulated attachment holes  221  may be positioned along the outside width contour  209  such that a first angulated attachment hole  221  of a first reinforcement bracket  200  is in a splicing opposing safety offset to a second angulated attachment hole  221  of a second reinforcement bracket  200 .  
      The color plots of  FIGS. 25-27 ,  30 - 42  illustrate the teachings described in reference to  FIGS. 22-24 . For that purpose, representative finite element analyses where computed with a computer program commercially available under the trade name ProMechanica. The I-joist  1 C with dimensions approximately corresponding to a standardized wooden I-joist of Table 1 having an approximate height 5 of about 9.5 inches was analyzed. For the purpose of simplicity, the I-joist  1 C was assumed monolithic with isotropic material properties of web  3  and chords  2 ,  4 , evenly loaded on the chord top  42  and supported via bearings  22 . Web enforcers  35  as are common in architectural constructions were also considered part of the monolithic I-joist  1 C.  FIG. 25  shows a portion AJ of the I-joist  1 C without web hole  17  as a reference stress plot. Test data of I-joist  1 C without web hole  17  as nominal reference values was obtained from manufacturers. The color offsets between chords  2 ,  4  and web  3  show steep stress gradients even for a monolithic I-joist  1 C of isotropic material. This demonstrates clearly the increased shear stress in the glue interface between web spigots  33  and chord grooves  21 ,  41 .  
       FIG. 26  shows the I-joist  1 C portion AJ with web hole  17  prescribed within the web hole boundary diameter  17 D. Stress maxima are clearly identifiable around the contour of hole  17 . Stress gradients in the web/chord interfaces are significantly steeper in the vicinity of the web hole  17  particularly demonstrating the necessity for reinforcement of the web/chord interface in the web hole  17  vicinity. Practical testing of has demonstrated about 40% ultimate nominal strength of an I-joist  1 ,  1 B,  1 C having a hole similar to web hole  17 .  
       FIG. 27  shows the internal displacement of the reinforcement structure  200  in general and the angular displacement of the bridging structure  210  with respect to the spacing structure  220  in particular, both resulting from the shear loads communicated between bridging structures  210  and the web  3  across the bridging height  210 H.  
      Front and Back views of the reinforcement bracket of  FIG. 22  under stress are shown in  FIGS. 31, 32 . Due to the missing curved rib island  271  the stress gradients along the transition radius  290 R is particularly steep at the reinforcement bracket  200  the bridging structure  210  of which is facing away from the web enforcer  35 . Spacing structures  210  span across both web/chord interfaces in the vicinity of the web hole  17  reducing peak stresses in both web/chord interfaces as illustrated in  FIGS. 32, 33 .  
      The stressed reinforcement bracket  200  of  FIG. 23, 24  is depicted in  FIG. 34  solely attached to the I-joist  1 C via attachment holes  212 . Friction between attachment faces  218  and web  3  is not considered. Shear load transfer is relatively low compared to attachment configurations of  FIGS. 37 and 40 . Stress peaks around the web hole  17  remain high and the stress gradients of the web/chord interface in the vicinity of the web hole  17  remain also at high levels as depicted in  FIGS. 35, 36 .  
      The stressed reinforcement bracket  200  of  FIG. 23, 24  is depicted in  FIG. 37  solely attached to the I-joist  1 C via attachment holes  212  with friction between attachment faces  218  and web  3 . The friction condition is approximated in the simulation by defining the attachment holes  212  and respective screw holes in the web  3  as rigidly connected. Shear load transfer is improved compared to attachment configuration of FIGS.  34  resulting in higher stress loads on the reinforcement bracket  200 . As stresses increase in the reinforcement bracket  200 , the curved rib islands  271  increasingly assists in flattening the stress gradients and lowering contour stress peaks in particular along the transition radii  290 R. Corresponding stress peaks around the web hole  17  as well as stress gradients of the web/chord interface in the vicinity of the web hole  17  are depicted in  FIGS. 38, 39  lower than in  FIGS. 35, 36 . From comparing  FIGS. 35, 36  with  FIGS. 38, 39  the significance of a rigid attachment of the bridging structure(s)  210  with the web  3  and consequently the significance of spacing holes  213  is clearly demonstrated.  
      The stressed reinforcement bracket  200  of  FIG. 23, 24  is depicted in  FIG. 38  attached to the I-joist  1 C via attachment holes  212  and angulated holes  221  with friction between attachment faces  218  and web  3  and friction between fourth reinforcement rib  240  and chord  2 . The friction condition is approximated in the simulation by defining the attachment holes  212 ,  221  and respective screw holes in the web  3  as rigidly connected. Shear load transfer is improved also along the outside with contour  209  compared to attachment configuration of  FIG. 37  resulting in more leveled stress loads on the reinforcement bracket  200  and flatter stress gradients in the web/chord interface in the vicinity of the outside width contour  209 . As shown in  FIGS. 41, 42 , stress peaks around the web hole  17  as well as stress gradients of the web/chord interface in the vicinity of the web hole  17  are lowest compared to  FIGS. 35, 36 ,  38 ,  39 . From comparing  FIGS. 35, 36 ,  38 ,  39 ,  41 ,  42  the significance of a rigid attachment of the outside width contour  209  with the web/chord interface and consequently the significance of angulated holes  221  is clearly demonstrated.  
      Chords  2 ,  4  are commonly made of stress graded wood with grain orientation substantially parallel to the I-joists&#39;  1 ,  1 B,  1 C, protrusion direction. Practical testing has demonstrated about 10% higher ultimate strengths for identical test setups except the reinforcement bracket  200  being attached once with a u-shape and once with an n-shape. This may be attributed to the fourth stiffening rib  240  opposing tertiary buckling forces of the compressed top chord  4  in chase in an n-shape type attachment of the reinforcement bracket  200 . Practical testing has demonstrated about 90% ultimate nominal strength of an I-joist  1 ,  1 B,  1 C having a hole similar to web hole  17  reinforced with a reinforcement bracket in n-shape attachment orientation. Practical testing has demonstrated about 80% ultimate nominal strength of an I-joist  1 ,  1 B,  1 C having a hole similar to web hole  17  reinforced with a reinforcement bracket in u-shape attachment orientation. The test results of reinforcement brackets  200  including the stiffening interface  290  demonstrated an approximate 10% increased failure load under otherwise substantially identical testing conditions.  
      Accordingly, the scope of the invention described in the Figures and the above Specification is set forth by the following claims and their legal equivalent.