Abstract:
A reduced eccentricity guardrail post connector is provided and includes a connection element having a tensile force resistant portion and a shear resistant portion, where a proximal end of the shear resistant portion is connected at about a normal angle to a distal end of the tensile force resistant portion. The post connector further includes a post coupler disposed at a proximal end of the tensile force resistant portion, where the post coupler compressively joins a post to a rim joist. Additionally, a joist coupler is disposed at a distal end of the shear resistant portion, where the joist coupler compressively joins the connector element to a joist. Further, a joist material strengthening element is disposed into the joist to resist tensile loads in joist material. The tensile resistant portion resists tensile loads and the shear resistant portion resist shear loads when the horizontal forces are imparted on the post.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is cross-referenced to and claims the benefit from U.S. Provisional Patent Application 60/995,165 filed Sep. 26, 2007, which is hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to a guardrail post connection. More particularly, the invention relates to securing a railing post to a deck base in a manner that provides both shear and tension strength to the post, while enabling easy and correct installation. 
       BACKGROUND 
       [0003]    Building codes require guardrail posts to resist 200 pounds at the top of the post in all directions with a safety factor of 2.5. The typical connections used to connect guardrail posts to wood framed decks fail to meet this requirement, according to published test results for a 36-inch post length. Current codes in many states now require the post connections pass a minimum 200-pound resistance test for a 42″ post length. 
         [0004]    One significant defect in guardrail post connectors that integrate both a rim joist and a joist to the post is the presence of an eccentric moment between the connector and the joist. A tensile load resistant component that is displaced from the connection to the joist creates an eccentric moment in the connection that limits the strength of the connection. Failure of the guardrail post and thereby guardrails have resulted in injuries and death. 
         [0005]    Accordingly, there is a need to develop a guardrail post connection that reduces or eliminates eccentric moments between the tensile force resistant section and the coupling at the joist, and enables easy and correct assembly of deck railing posts to a deck base while supplying substantial support 
       SUMMARY OF THE INVENTION 
       [0006]    To overcome the shortcomings in the art, reduced eccentricity moment guardrail post connector is provided. The reduced eccentricity moment guardrail post connector includes a guardrail post, a rim joist, a joist disposed perpendicularly at an end of the joist, where the guardrail post is disposed perpendicularly on the rim joist and perpendicularly to the joist. The invention further includes a connection element having a tensile force resistant portion and at least one shear resistant portion, where the tensile force resistant portion is connected at about a normal angle to a the shear force resistant portion, and the shear force resistant portion is disposed through the joist and compressively couples the tensile force resistant portion adjacent to the joist providing a reduced eccentricity moment between the tensile force resistant portion and the joist. Additionally, the tensile force resistant portion extends through the rim joist and the guardrail post and compressively couples the guardrail post to the rim joist and the tensile force resistant portion disposed along the joist. The reduced eccentric moment connector further includes a guardrail post coupler disposed at a proximal end of the tensile force resistant portion, where the guardrail post coupler provides the compressive joining of the guardrail post to the rim joist. A joist coupler is disposed at a distal end of the shear resistant portion, and provides the compressive joining of the connector element to a joist. A joist material strengthening element is disposed into the joist at an angle about parallel with the guardrail post, where the tensile force resistant portion resists tensile loads when horizontal forces are imparted on the guardrail post, the shear resistant portion resist shear forces when the horizontal forces are imparted on the post, and the material strengthening element resist tensile loads in the joist. 
         [0007]    In one embodiment of the invention, the connection element includes an angled rod, where the tensile force resistant portion is a proximal portion of the angled rod and the shear force resistant portion is a distal portion of the angled rod. In this embodiment, the shear resistant portion further includes a joist sleeve, where the distal portion of the angled rod is disposed through the joist sleeve and the joist sleeve is disposed through the joist. The joist sleeve can be a tube having a fillet feature inside the tube, where the fillet feature conforms to a bend in the angled rod. 
         [0008]    In another embodiment of the invention, the connection element is an angled plate having the tensile force resistant portion and a rim joist abutting portion, where a proximal end of the tensile force resistant portion is disposed at about a normal angle to the rim joist abutting portion. The current embodiment further includes at least one shear bolt hole disposed near a distal end of the tensile force resistant plate and through the tensile force resistant portion. At least one shear bolt is disposed through the shear bolt hole and through the joist, where the tensile force resistant portion is compressively coupled to the joist by a nut and washer threadably tightened to the shear bolt. A tensile rod channel is disposed in the proximal end of the tensile force resistant portion and through the rim joist abutting portion. Additionally, a tensile force resistant rod is fixedly attached along the tensile rod channel providing a reduced eccentricity moment between the tensile force resistant portion and the joist and extends through the rim joist and the guardrail post for the compressive connection. In one aspect of the current embodiment, the tensile force resistant rod is fixedly attached to the tensile rod channel using connectors selected from a group consisting of welding, treads to nut, and threads to welded threaded element. 
         [0009]    In another embodiment of the invention, the connection element includes a first flat plate, where the first flat plate is the tensile force resistant portion having a tensile force resistant rod channel disposed in a proximal end at least one shear bolt through hole disposed in a distal end, a second flat plate where the second flat plate is a rim joist abutting portion, a tensile force resistant rod, where a distal end of the tensile force resistant rod is fixedly attached to the tensile force resistant rod channel and the second flat plate is disposed at a normal angle along the tensile force resistant rod and at a normal angle to the first flat plate The current embodiment further includes at least one shear bolt disposed through the shear bolt through-hole and through the joist, where the tensile force resistant portion is compressively coupled to the joist by a nut and washer threadably tightened to the shear bolt, and a proximal end of the tensile force resistant rod extends through the rim joist and through the guardrail post, where the guardrail post is compressively coupled to the rim joist by the guardrail post coupler. 
         [0010]    In one aspect of the invention, the guardrail post coupler includes a nut and washer, where the nut fixedly attaches to threads of the tensile force resistant proximal end, and the nut fixedly compresses the washer to the post, whereby compressively joining the post to the rim joist. 
         [0011]    In another aspect of the invention, the joist coupler includes a nut and washer, where the nut fixedly attaches to threads of a distal end of the shear resistant portion, and the nut fixedly compresses the washer to the joist, whereby compressively joining the post to the joist 
         [0012]    In a further aspect of the invention, the joist material strengthening element can be a threaded screw or a nail, where the joist material strengthening element binds the joist material to prevent splitting of the joist material. 
         [0013]    The invention also includes a method of using the reduced eccentricity moment guardrail post connector by providing a deck that includes at least a deck floor, a deck rim joist and a joist, wherein the rim joist is disposed perpendicularly at an end of the joist and the guardrail post is disposed perpendicularly on the rim joist and perpendicularly to the joist. The method further includes providing at least one post for attaching to the rim joist and providing a connection element, where the connection element has a tensile force resistant portion and at least one shear resistant portion, and the tensile force resistant portion is connected at about a normal angle to a the shear force resistant portion, and the shear force resistant portion is disposed through the joist and compressively couples the tensile force resistant portion adjacent to the joist providing a reduced eccentricity moment between the tensile force resistant portion and the joist. The tensile force resistant portion extends through the rim joist and the guardrail post, and compressively couples the guardrail post to the rim joist, where the tensile force resistant portion is disposed along the joist. The method also includes providing a guardrail post coupler disposed at a proximal end of the tensile force resistant portion, where the guardrail post coupler provides the compressive joining of the guardrail post to the rim joist, and providing a joist coupler disposed at a distal end of the shear resistant portion, where the joist coupler provides the compressive joining of the connector element to a joist. The method also includes providing a joist material strengthening element disposed into the joist at an angle about parallel with the guardrail post, where the tensile force resistant portion resists tensile loads when horizontal forces are imparted on the guardrail post, the shear resistant portion resist shear forces when the horizontal forces are imparted on the post, and the material strengthening element resist tensile loads in the joist. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0014]    The objectives and advantages of the present invention will be understood by reading the following detailed description in conjunction with the drawing, in which: 
           [0015]      FIG. 1  shows an exploded perspective cutaway view of the guardrail post connector according to the present invention. 
           [0016]      FIGS. 2(   a )-( b ) show perspective cutaway views of the guardrail post connector according to the present invention. 
           [0017]      FIGS. 3(   a )-( d ) show perspective views of different embodiments of the guardrail post connector according to the present invention. 
           [0018]      FIGS. 4(   a )-( b ) show planar views of alternative configurations of the guardrail post connector according to the present invention. 
           [0019]      FIG. 5  shows a load-deflection graph of test results for the angled bracket embodiment of  FIG. 3(   a ) according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will readily appreciate that many variations and alterations to the following exemplary details are within the scope of the invention. Accordingly, the following preferred embodiment of the invention is set forth without any loss of generality to, and without imposing limitations upon, the claimed invention. 
         [0021]    A device enabling easy and correct assembly of deck railing posts to a deck base while supplying substantial support is provided. A method of fabricating the device is disclosed. 
         [0022]      FIG. 1  shows an exploded perspective cutaway view of the guardrail post connector assembly  100  according to one embodiment of the current invention. This embodiment includes a connector rod  102  having a shear connection section  104  and a tension connection section  106 , where the tension connection section  106  is disposed at approximately a normal angle to the shear connection section  104 . The connector rod  102  has a shaped shear sleeve  108  disposed about the shear connection section  104 . The connector rod  102  further has a threaded proximal end  110  and a threaded distal  112 , where the proximal end  110  is fitted through a rim joist  114  and through a guardrail post  116  then secured thereto using a threaded nut  118  and washer  120 . Additionally, the distal end  112  and shear sleeve  108  are fitted through a joist  122 , where the washer  120  and threaded nut  118  are assembled to the threaded distal end  112  of the rod  102 . At least one joist material strengthening element  124  is input to the joist  122  at an angle that is normal to both the shear connection section  104  and the tension connection section  106 , where the joist material strengthening element  124  supplements the strength of a region of the joist  122  around the shear sleeve  108  and shear connection section  104 . 
         [0023]    The diameter and length of the connector rod in combination with the location of the joist holes  126  and the material strengthening element  124  are specifically made to guide the location of the shear connection section  104  so the connection will provide adequate strength. The strength of the post to deck framing connection will be determined by the diameter of the connector rod  102 , the length of the connector rod  102  and the location of the holes  126  and the use of material strengthening elements  124  in the joist  122 . The device incorporates the strength needed to meet the requirements of the building code with economy by adjusting these dimensions. 
         [0024]    The addition of the material strengthening elements  124  enables the hole  126  to be placed closer to the top and/or bottom of the joist  122  so that greater leverage and capacity results. The current state of the art require a distance from the top and/or the bottom of the joist  122  to the hole  122  to avoid material failure and breaking. 
         [0025]      FIGS. 2(   a )-((b) show perspective cutaway views of the guardrail post connector assembly  100  according to the embodiment shown in  FIG. 1 . As shown in  FIG. 2(   a ), the connection rod  102  is inserted through the shear sleeve  108  (not shown) and the post  116  is secured to the rim joist  114 , and the material strengthening element  124  is shown incorporated in the top of the joist  122 . As shown in  FIG. 2(   b ), the threaded proximal end  110  of the connection rod  102  is inserted through the joist  122  and secured using the threaded nut  118  and washer  120 . The distal end  112  of the connection rod  102  is inserted through the rim joist  114  and guardrail post  116  and secured using the threaded nut  118  and washer  120 . The material strengthening element  124  is shown incorporated in the bottom of the joist  122 . It should be apparent that the size and shape of the washer  120  provides different advantages in strength and appearance, where a large circular shape or large square shape improves connection strength of the guardrail post  116 . 
         [0026]      FIGS. 3(   a )-( d ) show perspective views of some embodiments of the guardrail post connector  300 , with the post  116 , rim joist  114 , and joist  122  removed for illustrative purposes. According to  FIGS. 3(   a )-( c ), the embodiments include a connection element or connector plate  302  having a generally planar shear connection section  304  and a generally planar tension connection section  306 , where a distal end of the tension connection section  306  is disposed at approximately a normal angle to the shear connection section  304  proximal end. The connector plate  302  has at least one shear bolt  308  disposed through the tension connection section  306 . The shear bolt  308  inserts through the joist (not shown) to provide shear resistance when horizontal forces are exerted on the guardrail post (not shown). The connector plate  302  further has a connector rod receiving channel  310  disposed through the wall of the tension connection section  304  and through the wall of the shear connection section  302 . A connector rod  312  having a proximal end  314  and a distal end  316  is fixedly attached to the rod receiving channel  310 , where the proximal end  314  is fitted to the channel and secured thereto. Further shown is at least one material strengthening element  124  disposed in the joist (not shown) perpendicular to the shear bolt  308  and perpendicular to the connector rod  312 , where the number of material strengthening elements used is related to the required strengthening of the joist material. 
         [0027]    Referring to  FIG. 3(   a ), the connector plate  302  is shown with a threaded mounting element  318  connected to the rod receiving channel  310 , by welding  320  for example, and the connection rod  312  is a threaded bolt having threads at the proximal end  314  and a bolt head at the distal end  316 , with the threaded proximal end  314  inserted to the threaded mounting element  318 . 
         [0028]    Referring to  FIG. 3(   b ), the connector plate  302  is shown with a connection rod  312  that is threaded at the distal end  316  and unthreaded at the proximal end  314 , where the unthreaded proximal end is connected to the rod receiving channel  310 , by welding  320  for example. The guardrail post (not shown) is secured to the rim joist (not shown) when the nut  120  and washer  118  are tightened at the distal end  316  of the connection rod  312 . 
         [0029]    Referring to  FIG. 3(   c ), the connector plate  302  is shown with a shear connection section  304  incorporated with the connection rod  312 , by welding for example, and the connection rod  312  that is threaded at the distal end  316  and unthreaded at the proximal end  314 , where the unthreaded proximal end is connected to the rod receiving channel  310 , by welding  320  for example. The guardrail post (not shown) is secured to the rim joist (not shown) when the nut  120  and washer  118  are tightened at the distal end  316  of the connection rod  312 . 
         [0030]      FIG. 3(   d ) shows the guardrail post assembly of the apparatus in  FIG. 1 , with the post  116 , rim joist  116 , and joist  122  removed for illustrative purposes. The connection rod  102  is inserted through the shear sleeve  108  and the material strengthening element  124  is incorporated in the top of the joist  122  (not shown). The shear sleeve has a rounded feature  322  for conforming to a the bending shape of the connection rod  106 . Also shown, the threaded proximal end  110  of the connection rod  102  is secured using the threaded nut  118  and washer  120 . The distal end  112  of the connection rod  102  is secured using the threaded nut  118  and washer  120 . The material strengthening elements  124  are incorporated in the joist  122 . 
         [0031]      FIG. 4(   a )-( b ) show planar views of alternative configurations of the guardrail post connector according to the present invention.  FIG. 4(   a ) shows one configuration where two of the systems  300  described in  FIG. 3(   a ) are used to secure the guardrail post  116 . The configuration shown here shows the capacity to resist applied force (F) from both the inward and outward directions.  FIG. 4(   b ) shows another configuration where one of the systems  300  described in  FIG. 3(   a ) is used to secure the guardrail post  116 , and a-bolt assembly  404  is used as a bottom connection of the guardrail post  116 . The configuration shown here shows the capacity to resist applied force (F) from the outward direction. 
         [0032]    The inventor has performed controlled tests to verify the strength of the guardrail post connection meets structural code criteria.  FIG. 5  shows a load-deflection graph  500  of test results for the angled bracket embodiment of  FIG. 3(   a ) according to the present invention. A horizontal load was applied to the top region of the post and the post deflection was measured. The graph shows the integrity of the connection remains until approximately 530 pounds of horizontal force at almost 7-inches of deflection. 
         [0033]    As method of fabricating the guardrail post connector,  FIGS. 3(   a ) and  3 ( b ) provide an exemplary methods that includes fabricating the connector plate from a sheet of steel or the like, where at least one shear bolt hole and at least one rod receiving channel are disposed through the connector plate using stamping, cutting or machining techniques. Alternately, at least one shear hole and at least one threaded mounting element receiving channel are disposed through the connector plate using stamping, cutting or machining techniques. The connector plate is bent along the rod receiving or threaded mounting element receiving channel region and transverse to the plate length, at approximately a right angle. The receiving channel is made to span from along the tension connection section to along the shear connection section such that the receiving channel follows the bend in the connector plate. The rod having a proximal end and a threaded distal end is fixedly attached to the rod receiving channel, where the proximal end is fitted to the channel and secured thereto using welding techniques or the like. A washer and threaded nut are assembled to the threaded distal end of the rod. Alternately, the threaded mounting element is fixedly attached to the mounting element receiving channel so a bolt with a washer can be assembled to the coupler nut. 
         [0034]    The width and length of the connector plate in combination with the location of the holes are specifically made to guide the location of the shear bolts so the connection will provide adequate strength. The minimum distance of the first shear bolt from the end of the floor joist is guided by the distance from the normal angle of the connector plate to the first connector plate shear bolt hole and the minimum distance of the shear bolt to the top of the floor joist is guided by the width of the connector plate and the location of the shear bolt hole in the middle of the plate. The distance between the shear bolts is guided by the location of the holes in the connector plate. The strength of the post to deck framing connection will be determined by the width of the connector plate, the length of the connector plate, the location of the holes in the connector plate, and the material strengthening elements. The device incorporates the strength needed to meet the requirements of the building code with economy adding the material strengthening element and by adjusting these dimensions. 
         [0035]    The present invention has now been described in accordance with several exemplary embodiments, which are intended to be illustrative in all aspects, rather than restrictive. Thus, the present invention is capable of many variations in detailed implementation, which may be derived from the description contained herein by a person of ordinary skill in the art. For example, the guardrail post connector can be used to secure one or more rim joists  114  to the joists  122  to allow attachment of the post  116  to the rim joists  114  with bolts  404  or lag screws (not shown) at locations between the joists  122 . Further, the number and size of rim joists  114 , guardrail post connectors  102 , bolts  312 , washers  120  and screws or nails can be adjusted to provide the strength to meet the requirements of the building code with economy by adjusting the number and size. 
         [0036]    Further, dual guardrail post connectors can be used for greater capacity and larger posts by place in one on each side of the joist and bolting through the joist to connect the two guardrail post connectors with a bolt. 
         [0037]    Additionally, strength can be increased by using large washers on the outside of the post to distribute the load force over a wider area. 
         [0038]    All such variations are considered to be within the scope and spirit of the present invention as defined by the following claims and their legal equivalents.