Patent Abstract:
A safely device and method for construction sites provide secure and easy fastening of a sheet material over an opening in a concrete slab. By covering the opening, injuries and other risks posed by openings can be avoided. Holes are formed through the concrete around the opening and then a two part fastener is used to securely hold the sheet material (e.g., plywood).

Full Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to construction and more particularly, to safety systems and methods to employ during construction. 
       BACKGROUND 
       [0002]    During construction of large buildings, and even smaller buildings, there are often many concrete structures, such as floors, that have openings in them. These openings may be temporary during the actual construction of the building or they may be permanent features of the building. The purposes of the openings can vary widely. Some permit passageway of materials and equipment during the construction process or some may provide openings for conduit and duct work that will become part of the building upon completion. 
         [0003]    These openings present a safety hazard to the workers on the construction site and many ad-hoc methods of addressing the safety concerns have been developed. For example, one common method that is deployed as needed is simply power-nailing a piece of plywood over the hole to prevent a worker from falling in or through the hole. Because damaging the concrete surface is discouraged during construction, the nails used are often relatively short and, thus, do not provide great security and fastening strength. Furthermore, removing the sheet of plywood to temporarily provide access to the hole is difficult and the nails can not be re-used. 
         [0004]    Often many of the openings are ultimately re-filled as part of the construction process. Thus, some type of re-enforcing structure is utilized underneath an opening to support the concrete that is poured into the opening and allowed to set and cure. Thus, this requires the construction of other structures that can also potentially damage the concrete surface or, at the very least, be difficult to accomplish by one person. 
         [0005]    There remains a need in the industry to address these and other needs as described below with respect to various embodiments of the present invention. 
       SUMMARY OF THE INVENTION 
       [0006]    Embodiments of the present invention relate to a safety device and method for construction sites that provide secure and easy fastening of a sheet material over an opening in a concrete slab. By covering the opening, injuries and other risks posed by openings can be avoided. Holes are formed through the concrete around the opening and then a two part fastener is used to securely hold the sheet material (e.g., plywood). This approach also allows easy configuration of a method to re-fill the openings with concrete if desired. 
         [0007]    It is understood that other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein it is shown and described only various embodiments of the invention by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  depicts a support structure that is useful in accordance with the principles of the present invention for forming holes in concrete structures that allow safety devices and techniques to be utilized therein. 
           [0009]      FIG. 2  illustrates the structure of  FIG. 1  in operational use. 
           [0010]      FIG. 3  depicts an opening in a concrete slab  202  that has adjacent through holes  302 ,  304  in accordance with the principles of the present invention. 
           [0011]      FIG. 4  shows a top view of an opening  202  having one example pattern of through-holes in accordance with the principles of the present invention. 
           [0012]      FIG. 5  depicts the top view of  FIG. 4  but with a sheet of plywood or other material secured over the opening in accordance with the principles of the present invention. 
           [0013]      FIGS. 6 and 7  depict a side view of the two part fastener constructed in accordance with the principles of the present invention. 
           [0014]      FIGS. 8-10  depict a detailed view of the fastener of  FIGS. 6 and 7 . 
           [0015]      FIGS. 11 and 12  depict embodiments of the present invention in use with a whaler  1102 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring the concepts of the invention. 
         [0017]      FIG. 1  depicts a support structure that is useful, in accordance with the principles of the present invention for forming holes in concrete structures that allow safety devices and techniques to be utilized therein. The support structure  100  is depicted as a tripod-like device having three legs  102 ,  104 ,  106 . However, one of ordinary skill will recognize that a different number of legs could be used without departing from the scope of the present invention. Typical wire used for such a structure  100  can include, for example, the wire used for #9 and #10 wire chairs. 
         [0018]    The legs  102 ,  104 ,  106  support two rings  108 ,  110 . These rings are used to hold a dowel  112  in a generally upright position. Thus, the inner diameter of the rings  108 .  110  are sized to snugly match the outside diameter of the dowel  112 . One exemplary dowel  112  could be constructed from a length of PVC pipe that is readily available on most job sites. For example, using ¾ inch PVC pipe will result in a hole that accommodates a fastener device described later. The support structure  100  rests securely on a form  114 . Some or all of the legs  102 ,  104 ,  106  may include an opening, or loop that will hold a nail  116  or other fastener for securing the structure  100  in place on the form  114 . 
         [0019]    As for material, the support structure is beneficially constructed from light weight steel. However, composite materials as well as plastics may be used as well. In operation, the structure  100  will be placed in a poured concrete form and thus will be strong enough to withstand the pressures and forces of such an environment. The inside of the rings  108 ,  110  are preferably treated with some type of release agent so that the dowel  112  is easily removable from the structure  100 . Although a dowel is usually round in shape, other shaped (e.g., ellipses, square, etc.) may be used but some of the benefits provided by a round shape will not be realized. 
         [0020]      FIG. 2  illustrates the structure of  FIG. 1  in operational use. Only one structure is shown in  FIG. 2 ; however, multiple such structures would typically be used as described further herein. The structure  100  is placed within a concrete structure  204  (prior to pouring. This structure  204  includes an opening  202  that creates a safety risk for the workers during construction.  FIG. 2  depicts how a sheet of plywood or other material  200  can be placed over the opening  202 . One of ordinary skill will recognize that different dimensions can be used for the structure  100  based on the thickness of the slab of concrete  204 . Also, different coatings and materials can be used for the structure  100 . For example, if a steel tripod structure is used, then the bottom inch or so of the legs can be dipped in plastic or other material. 
         [0021]    In general, however, there are certain dimensions that can be utilized to provide particular benefits. For example, the distance “C” between the structure  100  and the opening  202  can be at least 4 inches. This will provide sufficient strength for the resulting hole. Also, the distance “A” can preferably be at least one inch form the top of the slap  204  to avoid any discoloration or other blemish to the surface of the slab  204 . For similar reasons, the distance “B” can preferably be 1 inch as well. These distances will also provide a structure that can securely hold the dowel  112  in the desired upright position. 
         [0022]    Once the concrete slab  204  is poured and cured, the dowels  112  is removed to create a through-hole  302  adjacent the opening  202 .  FIG. 3  depicts an opening in a concrete slab  202  that has adjacent through holes  302 .  304  in accordance with the principles of the present invention. 
         [0023]      FIG. 4  shows a top view of an opening  202  having one example pattern of through-holes in accordance with the principles of the present invention. The figure shows 6 holes  302 ,  304 ,  402  arranged around the perimeter of the opening  202 . Using fewer holes or using more holes, is contemplated within the scope of the present invention. For example, if a particular spacing (e.g. every 12 inches) between holes is desired, then sufficient holes to address any sized opening can be used. 
         [0024]      FIG. 5  depicts the top view of  FIG. 4  but with a sheet of plywood or other material secured over the opening in accordance with the principles of the present invention. In this example, only four holes were used so four fasteners  502 ,  4504 ,  506 ,  508  are used. These fasteners may, for example, be painted bright orange (or red, or fluorescent, etc.) to be visibly distinct. In operation, they securely hold the plywood  200  over the opening but will allow its removal relatively easily. 
         [0025]      FIGS. 6 and 7  depict a side view of the two part fastener constructed in accordance with the principles of the present invention. The fastener has a bent bolt  602  with a top structure that fits over the edge of the plywood  200 . This bolt  602  extends through the hole in the concrete slab and is threaded to match a nut  604 . As shown in  FIG. 7 , the nut  604  is sized sufficiently to hold a bottom sheet of plywood  702  in place as well. The bolt and nut can be painted or otherwise adorned with high-visibility markings to help further reduce risks of accidents on the work site. 
         [0026]      FIGS. 8-10  depict a detailed view of the fastener of  FIGS. 6 and 7 . The nut  604  has a threaded opening  802  that mates with the threads  1002  of the bent bolt  602 . The nut  604  has a number of purposes and can be sized in a variety of dimensions without departing from the scope of the present invention. Similarly, the bent bolt  602  can be used in varying thicknesses of concrete and thus must have a shaft  1004  that is long enough to extend through the slab for which it is being used. On a work site, workers appreciate tools that are easy to use and can be manipulated while wearing work gloves and using the other tools on hand without requiring specialized equipment. Thus, the bolt  602  and nut  604  are sized to allow hammering and banging with typical hammers on a job site. 
         [0027]    For example, the height “A” of the nut  604  is preferably about 2 inches with the lip “B” being about ¼ inch thick. The diameter “D” is approximately 4½ inches with an opening “E” roughly ½ inch in diameter. The resulting flange “C” is around 2 inches. 
         [0028]    As explained herein, the fastener structure ( 602 ,  604 ) may be used to hold an upper and lower sheet of plywood as well as a whaler (See  FIG. 11 ). If the plywood is assumed to be ¾ inches thick and the whaler is a standard 2×4, then the following dimensions provide for a beneficial bolt  602  and nut  604 . One of ordinary skill will recognize that these dimensions are merely an example and that the sizes may be modified to accommodate different sized support material. The bolt  602  can have a length “F” of the bent portion that is about 2 inches and if the shaft  1004  is about ½ inch thick, then the holding portion “G” is about 1½ inches. Thus, a worker would cut a piece of plywood to size to fit an opening yet extend towards a hole such that the bolt  602  would overlap and hold the plywood. The thickness “J” can be around 1 inch as such a thickness will allow it to be easily struck by a hammer. 
         [0029]    The inside bolt length “I” depends on the thickness of the slab. In practice, for example, the length should accommodate two pieces of ¾ in plywood, a 2×4 (roughly 4 inches wide) and the 2 inches of the nut  604 . Thus, the inside length “I” is preferably the thickness of the slab plus 7½ inches. For example, then, a ten inch slab would require a bolt  602  having an inside length “I” of 17½ inches. The minimum thread length “H” will have to accommodate the most minimal use which would be a single sheet of plywood. Thus, the minimum thread length “H” is the inside length “I” minus the slab thickness and ¾ inches. In the example bolt above for a 10″ slab, the inside length “I” was 17½ inches and, thus, the minimum thread length “H” is 6¾ inches. Again, one of ordinary skill will recognize that these lengths are exemplary only and other variations may be used without departing from the scope of the present invention. 
         [0030]      FIGS. 11 and 12  depict embodiments of the present invention in use with a whaler  1102 . Such a whaler  1102  would be used across the bottom of an opening to hold plywood  702  in place when re-filling the opening with concrete. As shown, the flange of the nut  604  is sized to accommodate the 2×4  1102 . Also visible in  FIG. 11  is the part  1104  of the nut  604  that is orthogonal to the plane of the drawing page. This part  1104  can be repeated around the nut  604  so that a user has multiple striking surfaces by which to tighten the nut  604 . 
         [0031]    In practice, a piece of plywood is cut to fit an opening and multiple bolts  602  are inserted in the holes along the perimeter of the opening. From below, the nuts  604  are threaded on the bolts  602  and tightened using a hammer or similar device. As mentioned earlier, an additional sheet of plywood and whaler can be used beneath the opening as well. From above, a worker can simply strike the bolt  602  to turn it 90 degrees so that it no longer overlaps the plywood. This allows the plywood to me removed (as needed) and then reattached by simply reversing the process to return the bolts  602  to a position where they overlap the plywood. From below, the nuts  604  can be removed without any coordination from above in order to add or remove a sheet of plywood and whaler. Because of the intended environment, the bolts and nuts are constructed from high strength materials such as steel or similar material. In addition, hardened steel or even more durable materials may be utilized if desired. Further-more, the openings shown in the attached figures have been roughly rectangular in shape. However, other shapes and even irregular shapes can be accommodated without departing from the scope of the present invention. 
         [0032]    The previous description is provided to enable any person skilled in the art to practice the various embodiments described herein. Various modifications lo these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. Thus, the claims are not intended to be limited to the embodiments shown herein, but are to be accorded the full scope consistent with each claim&#39;s language, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”

Technology Classification (CPC): 4