Patent Publication Number: US-2004045241-A1

Title: Isolation pocket form with closure

Description:
BACKGROUND OF THE INVENTION  
       [0001] This invention relates generally to the construction of large buildings of the type in which the structure of the building is supported atop vertical columns embedded in and extending upwardly from a concrete floor slab. More specifically, the invention relates to methods of creating isolation pockets about the bases of such steel support columns as the surrounding subgrade and concrete floor is formed to allow for adjustment of the columns and concrete encasement of the column bases.  
       [0002] Many large buildings, such as warehouses, shopping malls, and the like, are constructed with a steel super-structure that is supported at predetermined intervals atop vertical steel columns that are embedded at their bases within and extend upwardly from the concrete floor slab of the building. When constructing such buildings, concrete footings are generally cast in the ground at the prospective locations of the support columns with the footings having upper surfaces bearing anchor bolts to which the column bases are ultimately secured.  
       [0003] When the footings have thoroughly hardened, the vertically extending steel support columns are mounted thereto by means of the anchor bolts and the remaining steel super-structure of the building is constructed atop the columns. With the super-structure in place, box-shaped wooden forms known as column block-outs are typically built upon the footings surrounding and isolating the support column bases. The floor of the building is then prepared by grading, leveling, and compacting subbase material throughout the floor expanse to a predetermined depth. The subbase is compacted around and against the exterior surfaces of the wooden column block-outs, which isolate the column bases from the subbase material. The concrete slab is then poured on top of the subbase to the upper rims of the wooden forms and allowed to harden thoroughly. In this way, isolation pockets are formed in the floor slab around the bases of the support columns such that the column bases are isolated from the surrounding subbase material and concrete slab. The super-structure of the building can then be precisely aligned by appropriate adjustment of the column bases on their anchor bolts. With the super-structure precisely aligned, the wooden forms that created the isolation pockets in the floor slab are forcibly removed and the remaining voids are filled with concrete, which provides stability and additional anchoring for the columns, protects the column bases from corrosive elements, and completes the concrete floor of the building. In addition, crack control joints are usually cut in the concrete floor slab with the crack control joints extending between adjacent isolation pockets to provide for controlled cracking of the slab as it expands and contracts with changing temperature.  
       [0004] While the just described method of constructing isolation pockets has been used for years with a measure of success, it nevertheless embodies numerous inherent problems and shortcomings. The mere construction and placement of the wooden forms about the bases of support columns, for example, can be extremely time consuming and wasteful, particularly in very large buildings that may include hundreds of support columns. In addition, the removal of the forms once the surrounding slab has hardened can be even more time consuming and usually results in the destruction of the form and in some cracking and chipping of the concrete floor slab around the lips of the isolation pockets.  
       [0005] In addition to being time consuming and wasteful, prior art techniques utilizing removable wooden forms can and sometimes do result in serious structural problems. For example, when the wooden form is removed so that the isolation pocket can be filled with concrete, the dirt and gravel that typically makes up the subbase beneath the floor slab often becomes dislodged and falls into the isolation pocket creating a partial void beneath a portion of the slab. Such dislodging of the subbase material is virtually unavoidable since the wooden form usually must be removed forcefully with blows from hammers and the like. The long term result can be a deterioration in the strength of the slab and a future collapse thereof in the event a heavy weight, such as a forklift truck, is moved onto the weakened area of the slab. Another problem with current methods is the inherent requirement that the isolation pockets themselves be filled with concrete after the main slab has hardened and the wooden forms removed. Since the concrete slabs of most buildings will not support the weight of the concrete truck, the isolation pockets typically must be filled manually from wheelbarrows that are trucked by hand from a remotely located concrete truck across the floor slab to the locations of the isolation pockets. Again, this process is extremely labor intensive and thus wasteful of valuable time and money.  
       [0006] Thus, a continuing and heretofore unaddressed need exists for a method and apparatus for constructing isolation pockets that overcomes the problems and shortcomings of the prior art by eliminating wasteful form construction and removal, preventing the dislodging of subbase material in the region of isolation pockets, and eliminating the requirement that the isolation pockets themselves be filled with concrete after the main slab has hardened. It is to the provision of such a method and apparatus that the present invention is primarily directed.  
       [0007] My prior patent, U.S. Pat. No. 5,224,313, describes an improved method of constructing isolation pockets that utilizes isolation pocket forms that are prefabricated of a durable non-corrosive material and adapted to stay in place embedded within the building floor after construction is complete. In one preferred configuration, the prefabricated form is shaped as a rectangular box having outwardly extending flanges along its bottom edges and having an open top bounded by an upper peripheral lip of the form. In use, the support column footings are poured in the usual way and one of the prefabricated stay-in-place forms is secured to each footing surrounding the anchor bolts thereof. The form can be secured in place by means of concrete nails or other suitable fasteners driven through the lower peripheral flanges of the form and into the concrete material of its corresponding footing.  
       [0008] With one of the forms in place on each footing, the vertically extending steel support columns can be anchored to the footings by means of the anchor bolts and the steel superstructure of the building can be constructed atop the support columns. The super-structure can then be precisely aligned by appropriate manipulations and adjustments of the anchor bolt nuts.  
       [0009] With the footings, isolation pocket forms, support columns, and super-structure in place, the subbase of the building floor can be prepared by grading, leveling, and compacting dirt, gravel, and/or other subbase material within the bounds of the area to be occupied by the finished floor slab. The subbase material is compacted against the exterior surfaces of the isolation pocket forms to a predetermined depth below the upper lips of the forms. The concrete floor slab of the building can then be poured from concrete trucks beginning at one end of the building and working toward the other. However, rather than leaving the isolation pockets unfilled as with prior art methods, the floor slab can be poured and the isolation pockets filled concurrently during the same pouring operation. This is possible with the present invention because the isolation pocket form is adapted to be left in place embedded within the finished concrete floor of the building and does not have to be removed as do prior art wooden forms.  
       [0010] When the concrete of the floor and the isolation pockets have hardened, the exposed upper rim of each isolation pocket can be ground with a suitable grinding apparatus down to the level of the floor. In this way, the concrete does not have to be poured precisely to the rims of the isolation pocket forms but can be poured to a predetermined level below the rims, thus further saving time and money.  
       [0011] Since the floor slab is poured and the isolation pockets filled in the same operation, the highly labor intensive process of filling the isolation pockets from wheelbarrows is eliminated. Furthermore, the inefficient and wasteful construction and removal of prior art wooden forms is eliminated. Also, since the isolation pocket form of this invention stays-in-place embedded within the floor, the subbase material previously compacted against the form is maintained by the form in its highly compacted state such that the dislodging of subbase material in the immediate region of the isolation pockets commonly encountered in the past is eliminated.  
       SUMMARY OF THE INVENTION  
       [0012] An object of this invention is to provide an isolation pocket form with a closure which seats within the form, flush with the edge of the form. This an other objects are met by the invention shown in FIGS. 5 and 6 and described below. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0013]FIG. 1 is a perspective partially sectioned view of an isolation pocket portion of a concrete floor slab that embodies principles of the present invention in a preferred form.  
     [0014]FIG. 2 is a perspective expanded view of the first embodiment of an isolation pocket form constructed according to principles of this invention.  
     [0015]FIGS. 3 and 4 show a second embodiment of an isolation pocket form constructed according to principles of the present invention.  
     [0016]FIGS. 5 and 6 show a third embodiment of an isolation pocket form, having a closure.  
     [0017]FIG. 7 is a perspective view of one of the clips shown in FIG. 5.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0018] The floor structure  11  shown in FIG. 1 includes a generally rectangular concrete footing  12  that is formed with an upper load bearing surface  13 . A set of anchor bolts  14  (only two of which are exposed in FIG. 1) are embedded within and extend upwardly from the upper surface  13  of the footing  12 . The anchor bolts  14  provide means for securing the base plate  16  of a vertical support column  17  to the footing  12  using threaded nuts.  
     [0019] A generally rectangular open top form  19  is defined by four side panels  21  joined together at their ends with rivets or other suitable fasteners  22 . Each of the side panels  21  has a lower flange  23  that extends outwardly from the side panel along its bottom edge. The form  19  is mounted atop the footing  12  surrounding and isolating the base of support column  17  and is secured in place by means of concrete nails or other suitable fasteners  24  driven through the flanges  23  and into the concrete material of the footing  12 . The form  19  is constructed from four similar side panels  21 , and each panel  21  can be fabricated of a resilient, corrosion-resistant material such as polyethylene, polypropylene, polystyrene, or other suitable plastics.  
     [0020] A set of corner braces or brackets  20  are disposed in the junctions of adjacent side panels  21  and are secured to each adjoining panel by means of appropriate fasteners such as rivets  36 . The brackets  20  serve to brace and provide rigidity to the form  19 . Further, the brackets  20  provide for easy assembly of the forms  19  in the field such that the forms can be shipped in a compact disassembled configuration to save shipping costs. The brackets  20  are preferably formed of a metal. With this configuration, the form  19  creates an isolation pocket around the base of support column  17 .  
     [0021] The floor slab, generally indicated at reference numeral  26 , includes a layered compacted subbase  27  that provides support for the concrete slab surface  28  of the floor. The subbase  27  shown in FIG. 1 comprises a layer of compacted gravel  29  supported atop a layer of compacted dirt  31 . While such a gravel/dirt subbase is common in the construction industry, it will be understood by persons of skill in this art that the subbase  27  might well be formed of a variety of materials other than dirt and gravel. The dirt and gravel subbase of FIG. 1, therefore, is presented only as an illustrative embodiment and should not be construed as a limitation of the present invention.  
     [0022] The material of the subbase  27  is compacted against the exterior surface of the form  19 , which forms a barrier against migration of the subbase materials into the isolation pocket defined by the form  19 . A layer  18  of grout is sandwiched between the baseplate  16  of the support column  17  and the upper surface  13  of the footing  12 . This layer  18  of grout serves to transmit load pressures through the column  17  and into the footing  12 , stabilizes the footing  12 , and protects the under side of the baseplate  16  and the anchor bolts  14  from corrosive elements such as moisture.  
     [0023] The interior of the form  19 , which defines the isolation pocket itself, is filled with concrete to the level of the upper surface of slab  28 . The concrete  33  serves to anchor the base of the support column  17 , provide stability thereto, and protect the base of the column  17  against corrosive elements. Furthermore, the walls  21  of the form  19  function to separate the concrete  33  from the concrete of slab  28  to allow slight relative movement of the two masses of concrete. This movement can be important in preventing unwanted cracking of the concrete slab in the event of slight movements of support columns  17 . Linear crack control joints  34  typically are cut in the slab  28  with the crack control joints  34  extending between adjacent isolation pockets surrounding adjacent columns  17 . The crack control joints  3  provide for controlled cracking of the slab  28  as the slab expands and contracts in response to changing temperatures.  
     [0024] The upper peripheral rim of the form  19  is seen to be flush with the surface of the concrete floor slab and the concrete of the isolation pocket. As detailed below, this finished configuration can be accomplished by pouring the concrete to a predetermined level below the form upper rim and subsequently cutting or grinding the form down to the surface of the concrete slab. Alternately, the forms  19  can be constructed to have precise depths and the concrete can be poured and finished up to the level of the upper rims of the isolation pocket forms.  
     [0025] While only one isolation pocket and support column  17  is shown in FIG. 1, it will be understood that a large building such as a warehouse might include scores or even hundreds of such structures. In constructing these buildings, the concrete footings  12  are typically cast in the ground at the prospective locations of the support columns  17 . The footings  12  usually are cast with the anchor bolts  14  in place such that when the footing hardens the anchor bolts are embedded securely within and extend upwardly from the footings. With the footings  12  cast and thoroughly hardened, an isolation pocket form  19  can be secured to the upper surface of each footing surrounding and isolating the anchor bolts  14  of the footing. The forms can be secured in place by suitable fastening means driven through the form flanges  23  and into the concrete of the footings  12 . In this regard, it has been found expedient to fasten the forms to the footings using concrete nails fired from a conventional stud gun.  
     [0026] With the footings  12  and isolation pocket forms  19  in place, the vertical steel support column  17  can be anchored to their respective footings using anchor bolts  14  and nuts. In most instances, the support columns  17  are formed with a lower plate  16  having holes positioned to receive the anchor bolts  14 . Usually, each of the anchor bolts  14  includes a lower nut upon which the base of the column rests and an upper nut that can be tightened against the upper surface of the plate  16  to secure the column to the footing.  
     [0027] With the support columns  17  anchored to their respective footings  12 , the skeletal steel structure of the building can be constructed atop the columns  17 , which support the structure at predetermined intervals. The entire skeletal structure can then be precisely aligned through appropriate adjustments of the anchor bolt nuts  18 . When the structure has been aligned properly, grout  18  is injected beneath the baseplates  16  of the columns  17  and allowed to harden to support the load borne by the column and to protect the underside surface of the plates  16 .  
     [0028] The floor of the building can next be prepared by grading, leveling, and compacting the materials of the subbase  27  about and against the exterior surfaces of the isolation pocket forms  19  to a predetermined depth beneath the upper peripheral rims of the forms. It will be understood that at this stage of the construction procedure, the upper surfaces  13  of the footings  12  are covered with compacted subbase material outside of the forms  19  while the portion of the footing upper surfaces within the forms  19  as well as the bases of support columns  17  remain exposed within the isolation pocket.  
     [0029] Finally, the concrete floor slab itself can be poured from a concrete truck beginning at one end of the building and working toward the other end thereof. In pouring the floor, both the slab  28  and the concrete  33  within the isolation pockets are poured simultaneously. This is possible with the present invention because the isolation pocket form itself is constructed of a corrosion resistant material and is designed to remain in place embedded within the concrete floor of the finished building. The concrete  33  poured within the isolation pocket form serves to encase and protect the bases of the support columns  17  while providing additional anchoring weight for the bases Using the method of this invention, therefore, the inefficient and time-consuming construction and destruction of isolation pocket forms as well as the necessity that the pockets themselves be filled manually from wheelbarrows after the concrete of the slab  28  has hardened is completely eliminated. Thus, an enormous amount of time and effort and thus money is saved when principles of the present invention are applied.  
     [0030] Furthermore, the walls  21  of the embedded isolation pockets  19  provide for slight movement of the isolation pocket concrete  33  with respect to the slab  28  and thus tends to prevent unwanted cracking of the slab as the building structure moves in response to temperature or wind.  
     [0031] If desired, the concrete of the floor and the isolation pockets can be poured and finished precisely to the upper peripheral rims of the forms  19 , in which case the floor is completed when the concrete hardens. Alternatively, the concrete can be poured to a level below the upper rims of the forms and, upon hardening of the slab, the forms can be ground with an appropriate grinding device down to the level of the floor slab. With the latter method, precise and time consuming leveling and finishing of the slab during the pouring operation is eliminated.  
     [0032]FIGS. 3 and 4 illustrate a second embodiment of an isolation pocket form embodying principles of the present invention. The embodiment of FIGS. 3 and 4 is particularly suited to manufacture through an injection molding process and is therefore economical. The isolation pocket form  37  is constructed of four similar injection molded plastic panels  38  that are joined together at their ends to define the form. Each of the panels  38  comprises a wall  35  having a generally rectangular exterior face  39  and a lower flange  41  along its lower edge. An array of vertical buttresses  42  is integrally formed with each panel  38  and the buttress  42  extend between the panel outer face  39  and its lower flange  41 . The buttresses  4  provide rigid support for the flanges  41  and also increase the resiliency and strength of the panel outer faces  39 . The end vertical edges of each panel  38  are formed with locking protrusions  44  and  45 , with the protrusions  44  at one end being formed to engage and lock with protrusions  45 , so that the opposing ends of adjacent panels can be secured when the form  37  is constructed. In this regard, and as with the embodiment of FIG. 2, the forms can be shipped in a disassembled configuration and the panels can be secured together on site to create the forms  37 .  
     [0033] The exterior face  39  of each of the panels  38  also is formed with a pair of spaced parallel horizontal ribs  49  and  50 . The horizontal ribs  49  and  50  extend in a direction transverse to that of the buttresses  42  on the outside face of each panel  38 . The ribs are joined to the exterior face  39  of the panels and to the vertical buttresses  42 . In this way, the ribs  49  in conjunction with the buttresses  42  provide for a strong resilient structure that can withstand the compacting of subbase material and the pouring of a concrete slab against its outer surface.  
     [0034]FIGS. 5 and 6 show another modified form of the invention, which includes a closure  60  that may be applied when desired to cover the interior of the form, to prevent workers from tripping on or stepping into the form, to keep foreign materials out of the form, and to provide a flush floor surface for supporting tilt-up walls.  
     [0035] In this embodiment, as in that of FIGS.  3 - 4 , the form wall is preferably polygonal, most preferably square, and is formed of wall segments  62  which have coplanar upper edges. Each segment has external vertical and horizontal reinforcing ribs  64 ,  66  molded integrally with the segment. The edges of the wall segments are overlapped, and are attached to one another by means of bolts and nuts at each corner.  
     [0036] The form assembly is secured to the floor by clips  68  after the height of the form has been adjusted, if necessary, by inserting shims  70  beneath the segments. The fasteners which secure the clips to the floor are installed through the shims. One of the clips  68  is shown in detail in FIG. 7. It includes a base portion  72 , a plateau portion  73  offset upward from the base, and a projection or finger  74  extending downward from the end of the plateau.  
     [0037] Closure supporting ledges are formed by horizontal ribs  76  molded on the inside surface of each wall segment one and one-half inches from the top of the form. This distance corresponds to the thickness of the closure described below, and also permits one to fashion a cover from standard 2× lumber (e.g., 2×6&#39;s) when the top is not used or useable. This may occur when a post has been placed within the form.  
     [0038] The closure  60  itself has, as mentioned, a height of one and one-half inches. Its horizontal dimensions are chosen so that it fits closely within the top of the form. The closure is bounded by peripheral flanges  78 , and, as one can see in FIG. 6, the bottom of the closure has an array of mutually perpendicular reinforcing ribs  80 , to give the closure strength and rigidity. The reinforcement enables the closure to support substantial weight and ensures that it remains substantially planar under load.  
     [0039] The slots  82  in the top of the closure allow one to insert a hook-type tool (not shown) to lift the closure out of the form.  
     [0040] The form shown in FIG. 5 bounds a closed area which is square, but that area could just as well be any other shape, including circular or a polygon having any number of vertices. In the case of a circular form, the wall might be a single piece, or it might be assembled from segments, as described above.  
     [0041] The ribs  76  are only one way a ledge may be provided for supporting the closure, and other means will occur to those of skill in the art. For example, the wall might be stepped or rabbetted.  
     [0042] Since the invention is subject to modifications and variations, it is intended that the foregoing description and the accompanying drawings shall be interpreted as only illustrative of the invention defined by the following claims.