Abstract:
A removable support structure for concrete slab fabrication is described. A horizontally length adjustable latch device may be secured to both ends of shoring girders or shoring beams, or to just one end with a fixed in place latch secured at the other end, to permit rapid and accurate placement of the shoring support across a span to be structured in concrete. Vertical shoring posts and supports are eliminated, with the added advantage of the plane of the shoring always being automatically in the plane of the floor being formed. Bearing shoes on the ends of corrugated deck members, secured to building girders, cooperate with straps at their other ends, accurately and securely positions the corrugated decking in place. After the concrete has hardened, the entire support structure, including the shoring girders, shoring beams, and corrugated deck members, are rapidly and efficiently removed, ready for re-use.

Description:
BACKGROUND 
     This invention relates to the construction of concrete slabs, and in particular to a support structure that is rapidly and efficiently put in place, and rapidly and efficiently removed in condition for reuse. 
     Concrete slab construction is, of course, a routine method for horizontally covering open areas between columns and girders affixed to the walls of buildings, parking garages, and so on. A typical procedure for installing these concrete “floors” is to first place shoring members across the columns and girders, with shoring support posts rising from the ground or the deck below to the concrete floor being installed. Corrugated decking is then placed on the surface of the shoring, with the edges of the decking overlapping flange edges on the permanent building wall, girders and columns. Post-tensioning steel cables are then placed over the decking to add strength to the resultant structure. Conventional reinforcing bars can be used as well. Wet concrete is then poured over the corrugated decks. The concrete is then allowed to harden over a period of time. The supporting members can be so designed as to be removable after the concrete has hardened, simplifying concrete slab maintenance, and permitting re-use of the support structure on additional floors. 
     Various methods have been proposed for removable concrete slab support systems as is evident from the following examples. Keppler, in U.S. Pat. No. 1,707,226, discloses a supporting structure for concrete construction. This invention teaches a height adjustable shore  12  (centering post) cooperating with flanged  18  sheet metal members  16  (corrugated decking) connecting to height adjustable recesses  21  in soffit chairs. The invention notes (col. 2, lines 01-109), “after the concrete has been sufficiently set, the shoring may be removed and the ledgers taken down, whereby the centering forms with the soffit chairs may be removed and permanent shoring mounted in place to engage the soffit plates or boards for continuing to support the concrete until it is firmly set with full strength”. Lutz, in U.S. Pat. No. 3,059,738, discloses a removable concrete slab support wherein a portion of the support may be removed for the sake of economy prior to the concrete being fully set. An intermediate support  2  upheld by a prop  3  holds concrete slab supporting girders  1  and end supports  4  in place during the initial phase of setting wet concrete. Cornell, in U.S. Pat. No. 4,856,252, discloses a joist hanger  10  for removably securing a joist  38  during concrete slab construction. The joist hanger  10  has a box like metal configuration for securing the end of a suitable joist in the hanger. The joist hanger  10  has an extension section  18  for overlapping the top surface of a wall or girder  52 , with a roll bar  22  acting as a pivot located a spaced distance below the extension section. After a concrete slab  34  is solidified on as suitable support  36 , a sharp blow to the hanger causes it to pivot on roll bar  22 , thereby releasing the hanger  10 , joist, and support form the hardened concrete slab. 
     While these devices and methods disclose useful details for installation and removal of concrete slab support systems, they do not envision the efficiencies and conveniences inherent in the present invention. As will be more fully discussed below, this invention discloses a removable structure and method for supporting wet concrete during concrete slab construction without making use of vertical posts or shoring members which have to be supported down through the floors below to the ground. Accurate set up of corrugated decks is quickly accomplished to accept wet concrete. After the concrete has hardened all support members are quickly removed, ready for re-use as required. 
     It is therefore a primary object of the invention to provide a removable structure for supporting concrete slab construction that can be quickly put in place prior to the pouring of wet concrete, and quickly removed in re-usable condition after the concrete has hardened. 
     A further object of the invention is to eliminate the necessity for using vertical posts or shoring members which would have to be supported down through the floors below to the ground. 
     Another object of the invention is to permit the pouring and forming of a number of levels of concrete slabs in any desirable sequence. 
     Still another object of the invention is to provide for the plane of the shoring to always be automatically in the plane of the floor being formed. 
     A further object of the invention is to eliminate the necessity for permanently affixing structural support members to each other. 
     An additional object of the invention is to provide for most efficient placement of steel tendons within the concrete if post tensioning reinforcement concrete slab production is employed. 
     SUMMARY 
     In my application Ser. No. 09/041,944, filed Mar. 13, 1998, which is now U.S. Patent No. 5,906,076, the disclosure of which is hereby incorporated by reference, I describe a removable support for concrete slab construction and method which achieves the above mentioned objectives and others. The above mentioned U.S. Patent disclosed vertically and laterally adjustable latches affixed to ends of shoring girders and shoring beans for quick connection to pre-cut holes in permanent building girders and columns, and shoring girders and shoring beams. Bearing shoes on a first end of corrugated decks cooperate with locking straps at a second end of said decks to complete the structural elements of the invention. 
     I have now discovered that the removable support for concrete slab construction in my application Ser. No. 09/041,944, filed Mar. 13, 1998, now U.S. Pat. No. 5,906,076, can be improved by replacing the disclosed vertically and laterally adjustable latches affixed to appropriate ends of shoring girders and shoring beams with latches which can be extended horizontally forward away from or retracted towards the ends of said shoring girders and shoring beams as will be more fully described below. 
     In building construction, concrete floors are routinely installed horizontally between permanent building columns and girders supporting the walls of the building. Wet concrete is poured over usually temporary corrugated decking erected between the building girders and columns. Typically shoring posts are required, the posts extending vertically from the ground or previously formed floor, in order to support the temporary shoring. For a variety of reasons, including economy in building construction and ease of maintenance of the finished building, removal of the corrugated decking, temporary shoring, and vertical post supports is desirable. 
     I have found that concrete floors can be constructed faster and more efficiently by eliminating any necessity for temporary vertical shoring supports. This permits forming floors at any convenient level without concerns regarding foundation supports for temporary shoring. In addition, my method provides for precise, accurate placement of temporary supports in that when all elements are positioned they are all in their proper location with minimal field measuring or adjusting. 
     For example, my method makes use of a right angle grid of shoring girders and shoring beams positioned between the permanent steelwork comprising the building columns and girders. The shoring girders and shoring beams can be constructed from conventional steel “I” beams with their ends modified with a latch device which allows insertion into a support for quick erection, adjustment, and removal. The purpose of the shoring girders is to provide support for the shoring beams, with the shoring beams providing the support for the corrugated decks. Conventional corrugated decking is employed with the exception that the ends of the decking to be supported by the building “I” beams have a bearing shoe added to the closed end of the corrugated decking to facilitate removal from the hardened concrete with will be more fully described below. The bearing shoe also prevents vertical displacement of the decking due to wind and other construction forces. The bearing shoe further allows exact bearing length of the decking over the building girder. Locking straps, placed at the opposite end of the decking to be supported by the shoring beams, complete the precise, accurately secured concrete slab construction support system. 
     To construct a concrete floor, the end latches on the shoring girders are secured in pre-cut holes in the permanent building girders and/or columns. Latches on at least one end of each shoring girder or shoring beam are affixed to the end of each support member by means of an adjustable shear plate. The shear plate can be moved a spaced distance forward or backward in relation to the length of the shoring girder or shoring beam, thereby permitting horizontal length adjustment between the latch and the building girder, column, or shoring beam. The latch affixed to the other end of the shoring girder or shoring beam can be similarly adjustable lengthwise, or the latch can be simply permanently secured by means of bolts or welds. Similarly shoring beams are quickly secured at right. angles to the shoring girders again making use of pre-cut holes in the shoring girders to which the end latches on the shoring beams are secured. Corrugated decking is then positioned perpendicular to and between the permanent girders and the shoring beams, with the bearing shoe end of the deck engaging a top flange edge of the permanent girder, and with the opposite end of the deck, overlapping the end of a second corrugated deck, and being held in position by locking straps, all supported by the shoring beams. The locking straps secure the open ends of the decking together, and also insure that the bearing shoe end of the deck is held firmly in place against movement caused by workers or the elements, as well as facilitating removal of the decking. 
     With the removable support structure now quickly, accurately, and firmly in place the wet concrete can be poured onto the surface of the corrugated decks with reinforcement rods inserted, if required. For those applications requiring post tensioning of the concrete, steel tendons can now be placed not only above the furrows of the decking, but also within the furrows. The more favored placement of steel tendons is possible here where the decking is secured perpendicular to the permanent girders, and not parallel thereto, which is typical in existing concrete slab construction. After the concrete has hardened sufficiently to be self supporting, the complete removable support structure is quickly removed, all components being ready for re-use. The latch mechanism on the shoring girders and shoring beams is removed after restraining bolts are removed, by simply hammering from the opposite side or by prying from the tab side. Latches are designed with a sloped end so that once the latch moves beyond the flat section of the connecting support member, the sloped surface helps to remove the latch and drop the shoring girder or shoring beam. The bearing shoe construction now permits the decks to be quickly removed from the cured concrete by simply lowering the open ends and rocking them in a downward direction, which movement can be facilitated by making use of the locking straps which had previously been holding the decks in place. The shape of the shoe end allows the rocking motion to break the deck free of the hardened concrete. 
     Thus a new convenience in forming concrete slabs in buildings, parking garages, and the like is disclosed. A wet concrete support structure is described which is set in place with heretofore unobtainable speed and efficiency. Vertical support posts for the shoring are completely eliminated, permitting flooring levels to be constructed in any convenient sequence, while at the same time assuring that the shoring is always automatically in the plane of the floor being formed whether level or on a slope as in ramped floors. The perpendicular placement of the corrugated decks also permits placement of post tensioning steel tendons in the most favored position for strengthening the concrete. While the shoring girders and shoring beams have been described as preferably being modified steel “I” beams, it is to be noted that other shoring materials, including wood, plastic, and concrete, can be similarly employed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a schematic representation of a floor framing plan for one version of the invention. 
     FIG. 2 is a side elevational view of one version of the invention showing the bearing shoe modified end of a corrugated deck in contact with the top flange of a permanent building girder. 
     FIG. 3 is a side elevational schematic view of one version of the invention showing a strap securing the open ends of corrugated decks together. 
     FIG. 4 is a fragmentary, top plan view of one version of a first latch device of the invention attached to one end of a shoring girder. 
     FIG. 5 is a fragmentary, top plan view of one version of a first latch device of the invention at one end of a shoring beam being connected to a permanent building girder. 
     FIG. 6 is a side elevational view of two shoring beams having one version of a first latch device attached at one end of each beam, one first latch device at left shown fully extended and connected to a permanent building girder, with the second first latch device on the right shown fully contracted. 
     FIG. 7 is a top plan, schematic view of two first versions of the latch device of the invention shown fully extended and connected to a shoring girder. 
     FIG. 8 is a side elevational view of a shoring girder with a latch receiving plate attached. 
     FIG. 9 is a side elevational view of a second version of the latch device of the invention, the latch shown fully extended and connected to a permanent building girder, with a corrugated deck and bearing shoe shown in phantom. 
     FIG. 10 is an end view of a shoring girder with a second version of the latch device of the invention secured at one end of the girder. 
     FIG. 11 is a schematic representation of an end portion of a concrete slab supported by the removable support structure of one version of the invention, illustrating the placement of post tensioning steel tendons within the furrows of the corrugated decks. 
    
    
     DETAILED DESCRIPTION 
     Turning now to the drawings wherein like structures having the same function are referred to with the same numerals, in FIG. 1 a floor framing plan  10  according to the invention is shown. Building columns  16  and girders  14  form the permanent structural elements for holding up the walls of a building, parking garage, and the like. Shoring girders  18  are shown schematically as spanning the horizontal distance between oppositely positioned building columns  16 , or girders  14 . Shoring beams  20  also shown schematically interconnect the shoring girders  18 , and are spaced approximately equidistant and parallel to the girders  14 , spanning between the opposed walls of the building. Reference numerals  14 A and  18 A show permanent and shoring girder members positioned between respective columns  16 . Either can be used as the concrete support system design dictates. The shoring girder design,  18 A, similar to shoring girder  18 , has a suitable interface at each respective column to accept the latch portion of the latch engaging means as described generally hereinafter. 
     Corrugated decks  12  are shown positioned perpendicular to the permanent girders, with one end of each deck being supported by a shoring beam  20 , and the other end being supported by the top flange of a permanent girder or a plate attached to the top of a column. The number of individual corrugated decks is obviously not limited to two to span the entire distance between building walls. Intermediate sections of decking can be employed depending on particular building dimensions. The shoring girders and shoring beams of the invention can be standard, I-beam, steel building girders modified to have a latch device at each end as will be fully described. These shoring support members can also be fabricated in wood, plastic, or concrete. Standard steel corrugated decks can be employed as support members of the invention, modified to have a closed end  22  (FIG. 2) with bearing shoe structure  23  as will be more fully discussed. 
     In FIG. 2 the end of the corrugated deck  12  that rests on the building girder  14  is shown. Concrete  30  has been poured and hardened on the surface of the corrugated deck. Typical decks employed are normally longer in length than in width and will be so considered for the discussion of this invention. The upraised end portion adjacent each furrow  25  (see FIG. 11) at this end of the deck has a metal closure plate  22  to prevent passage of concrete through the open end to avoid encasement of the deck in concrete. 
     A bearing shoe  23  is affixed along the width of this end of the deck and secured to its underside. It contacts a top flange  15  of a building girder. The bearing shoe is comprised of four segments: a first segment  24  angled downward from the deck underside and contacting the top surface of the flange  15 ; a second segment  27  affixed to the underside of the deck immediately adjacent the closed end of the deck; a third segment  26  extending downward in a generally perpendicular direction t o the second segment  27 , to a point just about even with the underside of the flange; and a fourth segment  28  extending under the flange  15  at an obtuse angle to the third segment. The purpose of this bearing shoe structure is to provide a means for raising the front end of the corrugated deck  12  above the top surface of the top flange  15  of the building girder to facilitate the deck&#39;s subsequent removal; and to provide a means for grasping the extended lateral edge  15 A of the flange so as to accurately secure the decking in position, ready to accept the pouring of the wet concrete and to prevent accidental dislodgment by workers or the elements. 
     The straps  34  (FIG. 3) employed at the open, opposite end of a deck, which will be fully explained hereinafter, further insure the accurate, rigid deployment of the corrugated decks. After the concrete has hardened, the deck itself is not encased by the concrete. In FIG. 2, the deck  12 A shown in phantom, together with third and fourth bearing shoe segments,  26 A,  28 A, shown also in phantom, illustrate the ease with which the corrugated decking  12  can be removed after the concrete has hardened by simply pivoting about the contact surface between first segment  24  and the top of the flange while rocking the deck in a downward motion. 
     FIGS. 3-4 illustrate the strap securing method of the invention for connecting the open ends of the corrugated decks together where the decks  12 ,  13  overlap the shoring beams  20 . In FIG. 3 a strap  34  is shown securing a first deck  12  in contact with the top surface of flange  21  of a shoring beam  20  to a second deck  13  extending in the opposite direction, and positioned at its open end directly over the first deck. The ends of the strap  34  are shown before they are bent in a downward direction as indicated by the arrows, thereby linking the two open ends  32 A,  32 B, of the two decks together. Straps  34  can be made out of metal or plastic, sheet metal being preferred for its combination of strength and bendability. The straps are a few inches in width so as to fit into the furrows  25  of the corrugated decks, and of appropriate length so as to securely link the decks together. Usually one strap per deck pairing would be used, with the strap pre-hooked so as to engage the first deck  12  before the second deck unit is placed over the first deck. Before it is hammered in place to lock the decks together, the operator pulls on the strap so as to urge each deck  12 ,  13 , away from supporting beam  20 . This procedure keeps the bearing shoe end of the deck firmly and accurately secured on its girder flange  15  or column plate, and prevents dislodgment during construction due to workmen&#39;s activities, the elements, etc. The strap also assists in deck removal since the lower end of the strap can be grasped to pull the deck downward for removal. 
     FIG. 4 illustrates utilizing a wooden platform  36  placed on the top level surface of a top flange  21  of a shoring beam for providing a platform for the placement of the open ends of the decking. The wood platform  36  comprises one or more piece(s) of plywood stacked on top of each other. The platform extends in width just beyond the top flange  21 , thus providing a larger contact surface beneath the decking for a more stable condition. Further the wood is not as slippery as steel-on-steel when the decking is placed directly on the flange. Also, self-tapping screws can be used to secure corners, etc. of the decking down to the wood. Still further with the use of an appropriate thickness for the plywood piece(s), the height of the decking at the bearing shoe end  23  above the building girder top flange is compensated for at the shoring girders. As a result, the cooperating elements of the latching device disclosed hereinafter will lie essentially in the same plane. This facilitates the fabrication of substantially similar, support structure members, since the latch receiving openings are identically located in relation to the horizontal datum. 
     FIG. 4 also illustrates one version of the latch device  80  of the invention. The latch device is shown affixed to one end of a shoring girder  18 . The latch device  80  is comprised of two capture plates  84  affixed to opposite sides of one end of the shoring girder. This leaves a space between the plates  84  and the web angles  19  comprising the web structure of the shoring girder  18 . A bar  88  is affixed in place between the capture plates to maintain the clear space for the shear plate, and also to give the shear plate a surface to bear against when it takes up a load. A latch  82  is affixed to the end of the shear plate facing away from the end of the shoring girder, the latch  82  being wider than the shear plate  86  to provide a greater bearing surface onto the web hole  94  (FIG. 5) to which it is to be connected, and also to allow for vertical fillet welds (not shown) on each side of the shear plate. The latch  82  has a sloped end portion  82 A to facilitate removal after concrete pouring and hardening as will be more fully explained. A tab  92 , having a bolt hole  92 A approximately at its center, is affixed to the latch end of the shear plate in order to provide a bolted connection of the shear plate  86  to the permanent building girder  14  (or another shoring beam  20 ). This tab plate  92  also stabilizes the girder or beam against rotation during pouring of the concrete slab. In order to provide for horizontal movement of the latch  82  forward or rearward in relation to the end of the shoring girder  18 , a hole  98  is provided in the capture plate  84  which matches a slotted hole  100  in the shear plate. The effect of this version  80  of the latch device is to permit extension or retraction of the latch device over a spaced distance in a horizontal direction, thereby extending or shortening the length of the shoring girder or shoring beam as circumstances require. Once the proper setting is obtained a bolt  90  (FIG. 4) is inserted through the hole  98  in the capture plate  84  and the slotted hole  100  in the shear plate with a nut (not shown) securing bolt  90  in the appropriate position. In the case of shoring girder  18  having web angles  19  forming the web structure of the support member, the shear plate  86  is free to slide between the web angles. In the case of a solid web structure best seen in FIG. 6, a space  102  is cut out of the web structure to permit lateral movement of the shear plate  86  along the spaced distance. 
     In FIG. 5 a permanent building girder  14  is shown supporting a corrugated deck  12 . The bearing shoe channel  23  affixed to the end of the corrugated deck is shown overlapping a top flange portion of the girder. A pre-cut latch securing hole  94  accommodates a latch  82  affixed to the end of a shoring beam  20 . Precut bolt holes  96  at the lower left and right of the latch securing hole match bolt holes  92 A in the tab plate  92  affixed to each one of the shear plates. 
     The left portion of FIG. 6 shows a horizontally movable shear plate  86  fitted into a standard steel shoring beam  20 . Webbing has been removed, creating a space  102  to allow the shear plate  86  to slide forward or backward in a horizontal direction parallel to the top and bottom chords of the beam. Capture plates  84  are affixed to one end of the shoring beam  20  in a similar fashion to that described above for connection to an end of a shoring girder  18 . The latch  82  is shown in forward position connected to the pre-cut latch receiving hole  94  in the girder  14  and the tab plate  92  ready to be secured to the girder web. A similarly modified shoring beam is depicted on the right side of FIG. 6, showing the shear plate  86  in a retracted position for installation or removal. 
     In FIG. 7 two latch devices  80  are shown as being connected to the web section of a supporting member  18  from opposite sides. In this removable concrete slab support system all members supporting removable shoring members have pre-cut latch receiving holes  94  and bolt holes  96  fabricated in their webs to allow the latches  82  to penetrate and bear on the supporting webs and to allow for bolting the tab plate  92  to the web. The latch receiving holes in the web are sized to accept two latches. Facing the opening  94  from the shoring beam (or girder) side the latch is always positioned to the right side of the opening in order to minimize confusion by providing uniformity during the erection procedure, and, uniformity on the positioning of the tab plate securing bolts  104 . Referring to FIG. 1, this positioning of the latch to one side results in the skewing of the members as reflected by the center lines  55  and  57  of respective shoring girders and shoring beams  18  and  20 . The center or middle points  55 A and  57 A of each shoring member is in its true “center” position in the beam-girder support system. In this view the lower of the two latches is shown fully secured to a shoring girder web, with nut  106  securing bolt  104  to the tab plate  92  and shoring girder web. 
     As shown in FIG. 8, when the supporting member is another shoring joist girder  18  instead of a beam, a web plate  108  with an appropriate latch receiving hole  94 , and tab plate securing bolt holes  96  is fabricated in the shoring girder web angles  19  forming the web of this support members so as to be able to receive the latches from each side. 
     FIGS. 9 and 10 illustrate a second version  110  of the latch device of the invention. For many applications it would be possible to have one latch device fixed in place, and only one adjustable. In FIG. 9 one end of a shoring beam  20  is shown with a fixed in place latch device  110 , and similarly in FIG. 10 a shoring girder  18  is shown with a fixed in place latch device  110 . Bolt holes  98  in the capture plates are eliminated, as is the slotted hole  100  in the shear plate, the shear plate  86 A and capture plate  84 A being fixed in place by welding or other suitable means for securing the latch device to the ends of shoring members. 
     The above described latch devices offer a number of unique advantages: 
     (1) The latch is directly inserted into a latch receiving hole for erection without any further adjustments being required. 
     (2) To remove the latch the restraining bolts are removed, and the latch is retracted by hammering from the opposite side or by prying it from the tab side. Once the latch moves beyond the flat section of the supporting member web, the sloped end surfaces aid in removing the latch and dropping the shoring members. 
     (3) The adjustable length of the latch devices eliminates the requirements for exacting shoring member dimensions. 
     (4) The adjustable latch devices eliminate the necessity for shims between supporting beams and shoring members. 
     (5) An adjustable latch at one end of a shoring member usually permits the utilization of a fixed latch device at the other end of a shoring member, which significantly shortens time for both installation and removal. 
     FIG. 11 illustrates a unique advantage of the structure and method of the invention for those applications in which steel tendons  72  are employed to post tension a concrete slab. When corrugated decks are placed parallel to the permanent building girders and columns, as is typically the case in prior technology, the steel tendons, which need to be placed perpendicular to the permanent girders and columns, can only be placed above the furrows of the decks. Since the present invention calls for the placement of the decks perpendicular to the building girders and columns, it is now possible to place steel tendons within the furrows in the decking thus providing the same strength with a thinner deck. For example, the thickness of the shoring beams  20  can be reduced using additional layers of plywood or raising the location of the latch receiving hole  94  in shoring girders. When the concrete hardens, the post-tensioning effect is enhanced thereby increasing the structural strength of the deck. 
     After the wet concrete has been poured and then permitted to harden, and the post-tensioning effected, the weight of the system is now supported by the permanent structure. The removable support structure is now taken down with heretofore unobtainable ease and convenience, ready for re-use. The temporary bolts  96  are removed from the bolt holes in the beam, building girder or column. The shoring girder or beam is raised slightly to free the latch. The shoring girder or beam is now free to be moved to the right or left for easy removal. Similar actions at each shoring girder or beam, latch mechanism release these support structures for rapid removal. The straps at the open end of the decks can now be grasped and pulled downward to facilitate the downward motion of the bearing shoes  23  at the building girder or column supported ends of the decks. This motion causes the bearing shoes to break clear of the concrete at the supported end of the deck, with the complete corrugated deck now being free of the concrete slab, in condition for re-use. 
     While the present invention has been disclosed in connection with versions shown and described in detail, various modifications and improvements will become readily apparent to those skilled in the art. Accordingly, the spirit and scope of the present invention is to be limited only by the following claims.