Abstract:
An improved cementitious panel of the type which, in use, is supported, with its upper surface in biaxial compression, by steel beams and forms part of a deck or roof in a modular structure, wherein the improvement comprises a single layer of reinforcement in the panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to, and claims benefit of, U.S. Provisional Application Ser. No. 61/267,257, filed Dec. 7, 2009, Canadian Patent Application Serial Number 2,695,038, filed Feb. 27, 2010, and Canadian Patent Application Serial Number ______, filed Aug. 25, 2010, the disclosures of which are incorporated herein by reference in their entireties. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to modular buildings, such as parking structures. 
       BACKGROUND 
       [0003]    Modular parking structures are well known in the art. One structure used in Europe is the system sold under the trade-mark GOBACAR by GOLDBECK GmbH. This structure comprises pre-cast cementitious (steel-reinforced concrete) parking deck panels which are set onto cambered beams which in turn are fastened to and supported by vertical perimeter steel columns. The structure offers a visually attractive free-span design. As such, the usefulness of the structure is not limited to use in parking structures and it is known to be employed for other multi-level structures. 
         [0004]    The process of assembling the GOBACAR structure generally comprises the following steps:
       assembling the beams and columns into a support structure;   installing temporary horizontal beam support;   placing the panels;   grouting the gaps; and   removing the temporary horizontal beam support.       
 
       Concrete Deck Panel 
       [0010]    A concrete panel of the prior art will now be described with general reference to  FIGS. 1-3  of the drawings. 
         [0011]    The concrete panel  100  is generally rectangular in shape and planar. On two opposite sides  102 , 104  of the panel there are provided a plurality of recesses  106 . In this panel, these sides are 2.5 metres apart. On the other two sides  108 , 110  there are defined grooves  112 . In this panel, these sides are about 9.0 metres apart. 
         [0012]    A plurality of hook bars  114  in the form of 13 mm diameter u-shaped rebar elements are cast in the concrete such that the rebar lies substantially coplanar with the panel, the open ends of the hook bars are embedded in the concrete and the looped ends protrude into the recesses  106 . 
         [0013]    Two rebar reinforcement lattices  116  are provided. The lattices  116  are disposed in stacked, spaced relation, centered within the body of the panel  100  and dimensioned similarly to but slightly smaller than the panel such that, when positioned, there is clearance between the rebar lattices  116  and the outer edges of the concrete. The rebar in the lattices  116  is tied together with steel wire. 
         [0014]    The thickness of the panel is 103 mm and is denoted by dimension A 1  in  FIG. 3 . The minimum depth of the u-shaped rebar elements  114  and the rebar mat  116  from the upper surface of the panel, i.e. the amount of concrete coverage, ranges between 42 mm and 45 mm and is denoted by dimension B 1  in  FIG. 3 . 
       The Support Structure 
       [0015]    A support structure is shown schematically in  FIG. 4  and will be seen to include a group of horizontal cambered beams  118 . The beams  118  are substantially parallel, coplanar and laterally spaced from one another. 
         [0016]    A plurality of substantially vertical columns  120  are regularly-spaced, disposed in two rows and connected to beams  118  such that each beam  118  is supported at its ends by a pair of the columns  120 . The beams  118  and columns  120  are joined together by fasteners (not shown) and all are usually galvanized. The use of fasteners as compared to welds not only maintains the galvanization, therefore protecting the steel from the elements, but allows for a modular design that can be relatively quickly and easily assembled (or disassembled at end-of-life). The camber in the beams  118  is such that each beam  118 , when installed, is slightly higher at its midpoint than at its ends. Each beam  118  has on its upper convex surface a plurality of Nelson studs  122 . The outermost beams  118  have the studs  122  disposed in a single row; the inner beams  118  have paired studs  122 . 
       Employing Horizontal Beam Support 
       [0017]    The temporary horizontal beam support involves the placement of a jack  124  at the end of each beam  118 , as shown in  FIG. 5 . 
       Panel Placement 
       [0018]    With the beams  118  temporarily reinforced by the jacks, the roof/deck panels  100  are set on the beams  118 , such that each panel  100  is supported at its sides  102 , 104  by an adjacent pair of the horizontal beams  118  and such that each adjacent pair of horizontal beams  118  supports a plurality of deck panels  100 , which panels  100  are arranged in end-to-end relation, thereby to define transverse gaps  126  between longitudinally-adjacent deck panels and longitudinal gaps  128  between laterally-adjacent deck panels, all as shown in  FIG. 6 . 
         [0019]    In the course of assembly, the looped-ends of the u-shaped rebar hooks  114  are placed over the Nelson studs  122  which protrude from the beams  118 , thereby to provide a mechanical connection between the panels  100  and beams  118  and to provide a rough location mechanism. 
         [0020]    This is illustrated more clearly in  FIG. 7 , which shows a side view of a beam  118 , a plurality of Nelson studs  122  protruding from the beam  118 , the sides of a pair of longitudinally-adjacent panels  100  and the hook bars  114  protruding therefrom engaged with the Nelson studs  122 . 
         [0021]    At the ends of the beam  118 , closed hooks  130  are laid upon adjacent hook bars  114 , to mechanically connect laterally-adjacent Nelson studs  122 , as shown in  FIG. 8 . 
         [0022]    To ensure proper positioning of the deck panels  100  on the beams  118 , a locating pin may be precisely placed on the beam, and a socket, for receiving the pin in tight-fitting, locating relation, may be cast on the panel (none shown). The pin/socket arrangement also provides a mechanical connection between the panels and beams, which is of advantage in the assembly process in that it braces the structure together. 
       Filling the Gaps and Releasing Horizontal Beam Support 
       [0023]    Once the panels  100  are properly positioned, the transverse gaps  126  and longitudinal gaps  128  are filled with a grout. To temporarily hold the grout in place during solidification, foam gaskets (not shown) are fitted on the beams  118 , and at the base of the transverse gaps  126 . Once the grout has hardened, the horizontal beam supporting jacks  124  are removed. Removal of the jack supports  124  allows the weight of the concrete panels  100  to reduce the camber of the horizontal beams  118  through elastic deformation. This deformation of the underlying beams  118  causes the upper surface of the concrete panels  100  to be put into compression, in a direction parallel to the beams  118 . The upper surfaces of the deck panels  100  are also in compression in a transverse direction, as a result of the side support thereof (by the adjacent beams  118 ). 
         [0024]      FIGS. 9-11  show the structure after the grout has hardened and the jacks have been removed. 
         [0025]    These aforementioned biaxial compressive stresses tend to avoid crack propagation in the concrete upper surface. 
         [0026]    An impermeable waterproofing topping  132  is advantageously applied at least over the grout, as the upper surface of the grout over the longitudinal gaps  128  is under tension and otherwise susceptible to cracks and associated water and salt infiltration, which would otherwise promote corrosion and generally reduce the expected lifespan of the structure. The finished structure, i.e. with the grout  132  applied, is shown in  FIG. 12  and in section in  FIG. 13 . Herein it will be also seen that the centerline of the hook bars  114  is 50 mm above the bottom surface of the panel  100 , as indicated by dimension D 1 . The overall height of the Nelson studs  122  is 75 mm and indicated by dimension E 1 . The offset F 1 , between the underside of the head of the Nelson studs  122  and the centerline of the hook bars, is 13 mm. The amount by which panels  100  overlap the beam  118  is 10 mm, as indicated by dimension C 1 . 
       SUMMARY OF THE DISCLOSURE 
       [0027]    An improved cementitious panel forms one aspect of the invention. The panel is of the type which, in use, is supported, with its upper surface in biaxial compression, by steel beams and forms part of a deck or roof in a modular structure. The improvement comprises a single layer of reinforcement in said panel. 
         [0028]    According to another aspect of the invention, this panel can have concrete cover greater than 45 mm and a thickness between about 81 mm and about 126 mm. 
         [0029]    According to other aspects of the invention, with respect to either of the panels above, the reinforcement can be a reinforcing lattice. 
         [0030]    According to another aspect of the invention, the reinforcing lattice can be constructed from one or more of: glass-fibre reinforced polymer; stainless steel; hot-rolled deformed reinforcing rod; cold-rolled deformed reinforcing rod; and high-tensile cold-drawn wire. 
         [0031]    According to another aspect of the invention, the lattice can comprise:
       about 8 mm diameter high tensile cold-drawn wire extending transversely of the panel; and about 6 mm diameter high tensile cold-drawn wire extending longitudinally of the panel and rigidly interconnecting the about 8 mm wire; or   about 10 mm diameter deformed reinforcing rods extending longitudinally of the panel; and about 10 mm diameter deformed reinforcing rods extending transversely of the panel and rigidly interconnected to the longitudinally-extending rods by wire.       
 
         [0034]    Forming another aspect of the invention is another improved cementitious panel. This panel is of the type which, in use, is supported, with its upper surface in biaxial compression, by steel beams and forms part of a deck or roof in a modular structure. In this panel, the improvement comprises concrete cover greater than 45 mm and a thickness between about 81 mm and about 126 mm. 
         [0035]    According to other aspects of the invention, either of the panels above can:
       have concrete cover between about 50 mm and about 59 mm and a thickness between about 101 mm and about 105 mm; and/or   have about 55 mm concrete cover and a thickness of about 105 mm; and/or   in use, span between about 2.5 metres and about 3.0 metres between beams; and/or   in use, span about 2.8 metres or about 2.5 metres between beams; and/or   in use, span up to about 10 metres along the beams supporting it       
 
         [0041]    Forming another aspect of the invention is an improved modular structure. 
         [0042]    The structure is of the type including panels which: each have a cementitious part; in use, are supported, each with its upper surface in biaxial compression, by steel beams and form part of a roof or deck of said structure; and are mechanically coupled to the beams by hook bars which extend from the panels to engage Nelson studs protruding from the beams. 
         [0043]    The improvement comprises: a differential elevation, between the underside of the head of each Nelson stud and the centerline of the hook bar which engages said each Nelson stud, greater than 13 mm. 
         [0044]    Forming another aspect of the invention is another improved modular structure. The modular structure is again of the type including panels which: each have a cementitious part; in use, are supported, each with its upper surface in biaxial compression, by steel beams and form part of a roof or deck of said structure; and are mechanically coupled to the beams by hook bars which extend from the panels to engage Nelson studs protruding from the beams. 
         [0045]    In this improved structure, the improvement comprises: the use of the inventive panels; and a differential elevation, between the underside of the head of each Nelson stud and the centerline of the hook bar which engages said each Nelson stud, between about 18 mm to about 53 mm. 
         [0046]    According to other aspects of the invention, with respect to either structure:
       the differential elevation between the underside of the head of each Nelson stud and the centerline of the hook bar which engages said each Nelson stud can be about 29 mm to about 33 mm; and/or   the differential elevation between the underside of the head of each Nelson stud and the centerline of the hook bar which engages said each Nelson stud can be about 29 mm; and/or   the Nelson studs can have a height of about 80 mm to about 100 mm and the hook bars can have a diameter of about 10 mm; and/or   the Nelson studs can have a height of about 80 mm.       
 
         [0051]    Forming yet another aspect of the invention is a facility comprising a mixer, a molding area and a rail-mounted concrete dispenser/finisher. 
         [0052]    The mixer is for producing a supply of fluid concrete. 
         [0053]    The molding area is for receiving a mold in use. 
         [0054]    The concrete dispenser/finisher is in the form of a gantry adapted to, in use, receive said supply of fluid concrete from the mixer and deliver said supply of fluid concrete to the mold. The gantry includes dual vibrating screeds which move between raised and lowered positions. In use: (i) the gantry fills the mold with said supply of fluid concrete and finishes the concrete in a first pass over the mold with the screeds in the lowered positions; and (ii) the gantry returns towards the mixer in a second pass over the mold with the screeds in the raised positions. 
         [0055]    According to another aspect of the invention, the facility can further comprise: a staging area, in which the mold is placed before filling; and a thumper cart, which transports the mold by rail from the staging area to the molding area for filling and, after the gantry has made its first pass, vibrates the mold to remove voids from the fluid concrete contained therewithin. 
         [0056]    According to yet another aspect of the invention, as part of the vibration of the mold, the thumper cart can repeatedly drop the mold onto the floor. 
         [0057]    Advantages of the invention will become apparent to persons of ordinary skill in the art upon review of the appended claims and upon review of the following detailed description of an exemplary embodiment of the invention and the accompanying drawings, the latter being described briefly hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0058]      FIG. 1  is a perspective view of a panel according to the prior art; 
           [0059]      FIG. 2  is an enlarged partial plan view of encircled area  2  of  FIG. 1 ; 
           [0060]      FIG. 3  is a side view of the structure of  FIG. 2 ; 
           [0061]      FIG. 4  is a schematic view of a support structure according to the prior art; 
           [0062]      FIG. 5  is a view of the structure of  FIG. 4 , with jacks installed; 
           [0063]      FIG. 6  is a view of the structure of  FIG. 5 , with panels installed; 
           [0064]      FIG. 7  is a partial sectional view along  7 - 7  of  FIG. 6 ; 
           [0065]      FIG. 8  is a partial top plan view of the structure of  FIG. 6 , with a closed hook installed; 
           [0066]      FIG. 9  is a view similar to  FIG. 6  with the jacks removed and grout installed; 
           [0067]      FIG. 10  is a view along  10 - 10  of  FIG. 9 ; 
           [0068]      FIG. 11  is a view along  11 - 11  of  FIG. 9 ; 
           [0069]      FIG. 12  is a view similar to  FIG. 9  with top-coat applied; 
           [0070]      FIG. 13  is a view similar to  FIG. 10  with top-coat applied; 
           [0071]      FIG. 14  is a top plan view of a mold according to an exemplary embodiment of the invention; 
           [0072]      FIG. 15  is a top plan view of the interior of the mold in use; 
           [0073]      FIG. 16  is a schematic view of the molding part of a panel building facility according to an exemplary embodiment of the invention; 
           [0074]      FIG. 17  is a detailed perspective view of the structure indicated in encircled area  17  of  FIG. 16 ; 
           [0075]      FIG. 18  is a detailed perspective view of the component indicated in encircled area  18  of  FIG. 16 ; 
           [0076]      FIG. 19  is a partial, enlarged view of the structure of  FIG. 18 , from another vantage point; 
           [0077]      FIG. 20  is a detailed perspective view of the component indicated in encircled area  20  of  FIG. 16 ; 
           [0078]      FIG. 21  is an enlarged view of the structure of  FIG. 20 , from another vantage point; 
           [0079]      FIG. 22  is a view of the components of encircled areas  17 ,  18 ,  20  and  22  of  FIG. 16 ; 
           [0080]      FIG. 23  is a view of a panel constructed according to the exemplary embodiment, the view being similar to  FIG. 3 ; 
           [0081]      FIG. 24  is a view identical to  FIG. 13 ; 
           [0082]      FIG. 25  is a view similar to  FIG. 13 , but of a structure constructed with the panel of  FIG. 23 ; and 
           [0083]      FIG. 26  is a view similar to  FIG. 25 , of a structure according to another exemplary embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0084]    An exemplary process for manufacturing pre-cast panels is hereinafter described in detail, but for clarity, the concrete and mold used in the exemplary process are initially described. 
       Concrete 
       [0085]    The concrete employed in the exemplary embodiment has the following physical properties:
       compressive strength&gt;45 MPa in 28 days
           CSA 23.2-9C/ASTMA C1074   
           water absorption&lt;4% [CSA A23.2-11C]   salt scaling freeze/thaw&lt;800 mg/m 2  
           MTO LS-412/ASTMA C672   
           linear shrinkage&lt;0.04% [MTO LS-435]   chloride permeability&lt;1000 Coulombs [ASTMA C1202]   chloride diffusion coefficient&lt;1.8×10 −12  m 2 /s   lifecycle&gt;40 years according to LIFE365 model       
 
         [0095]    Concrete having these performance characteristics can be readily produced by persons of ordinary skill in the art, and thus, is not described herein in detail. 
       Mold 
       [0096]    With general reference to  FIG. 14 , the exemplary mold  220  is in the form of a table and will be seen to be comprised of side bars  222 , 224  and end bars  226 , 228 , collectively referred to as the perimeter bars, and a surface die  230 . The surface die  230  has a textured upper surface and forms the surface of the mold table. Side bars  222 , 224  and end  226 , 228  bars are releasably attached to the mold table by fasteners (not shown). The side bars  222 , 224  have trapezoidal protusions  232  formed thereon, to define recesses in the finished panels, these protrusions  232  having slots (not shown) defined therethrough. 
       The Mold Table in Use 
       [0097]    The mold  220  is used with internal elements which include cementitious bar chairs, a rebar mat  234  and hook bars in the form of u-shaped rebar elements  236 .  FIG. 15  is a plan view showing the position of the rebar mat  234  and the hook bars  236  with relation to the inside perimeter of the mold  220 , the perimeter being indicated in dotted outline  238 . The rebar mat  234  is made out of 8 mm diameter high tensile cold drawn steel wire  251  extending traversely of the panel and 6 mm diameter steel cold drawn wire  253  extending longitudinally, welded together in a lattice that is slightly smaller in external dimensions than the interior dimensions of the mold and, in use, is supported on the bar chairs (not shown) which are placed throughout the mold  20  to elevate the reinforcement  234  a predetermined distance from the surface die  230 . 
         [0098]    The hook bars  236  are 10 mm diameter rebar elements which extend through the slots in the protrusions  232 . With the internal elements positioned as indicated above, the mold  220  is ready to be filled with concrete. 
         [0099]    With regard to the bar chairs, not shown, same are cementitious, since, in the molding process, they rest on the surface die  230  which, as discussed further below, forms the upper surface of the finished panel; this means that the bases of the bar chairs define part of the upper surface. 
         [0100]    For this reason, the bar chairs are advantageously made corrosion resistant and otherwise compatible with the concrete, so as to avoid the potential for crack propagation, water or salt infiltration, etc. 
       Process 
       [0101]    The exemplary process for constructing panels will now be described. 
         [0102]    The process involves the use of a manufacturing system which includes a molding system and a de-molding system. 
         [0103]    The exemplary molding system includes molds  220 , a thumper cart  240 , a gantry  242  and a mixer  244 , all as indicated in  FIGS. 16-22 . The molding system is disposed in a facility having an indoor molding area  246 , an indoor staging area  248  and an indoor solidifying area  250 , all as indicated schematically in  FIG. 16 . 
         [0104]    In a starting configuration:
       the gantry  242  is disposed in position under the mixer  244  to receive a batch of fluid concrete;   a mold  220  is disposed at the molding position  246 , ready to receive fluid concrete; and   the thumper table  240  is disposed at the molding position  246 , beneath the mold  220         
 
         [0108]    Once the gantry  242  is filled with fluid concrete, it travels along outer rails  252  towards the molding area  254 , until its chute  256  is above the mold  220 . Then, the chute  256  is opened and the gantry  242  moves over the mold  220 , filling it with fluid concrete. 
         [0109]    Trailing the chute  256  are twin vibrating screeds  258  which screed the fluid concrete, to produce, in a single pass, a finished concrete surface. 
         [0110]    After the first pass has been completed, the screeds elevate  258 , and the gantry  242  retracts to its original position under the mixer  244 . 
         [0111]    With the gantry  242  retracted, the thumper cart  240  vibrates the mold  220 . The thumper table  240  has hydraulic lifters  260 , that elevate the mold  220  and then quickly retract, to drop the mold  220  against steel plates embedded in the floor. 
         [0112]    The impact of the mold  220  striking the floor produces strong vibrations that remove most voids from the concrete. 
         [0113]    Importantly, the concrete facing the surface die  230 , which ultimately forms the upper surface of the deck panel, obtains a relatively smooth, void-free surface through this process. 
         [0114]    Once vibration has completed, and the desired substantially void-free casting has been created:
       the mold  220  is moved from the molding position by an overhead crane and taken to the hardening area  250 ; and   contemporaneously, the thumper cart  240  moves to the staging area  248 , to pick up an empty mold, for subsequent filling, and transport the empty mold to the molding area  246 .       
 
         [0117]    Multiple advantages flow from the present molding process and facility as compared to the known prior art. 
         [0118]    As one advantage, the use of twin screeds provides a satisfactory surface finish without hand finishing, thereby reducing labor costs. 
         [0119]    As another advantage, the use of dual rails decouples mold removal from mold placement, to permit increased production rates. The use of a rail system, particularly, allows for relatively precise, quick movement of the mold table to the molding position from the staging area. 
       Concrete Slab 
       [0120]    After the concrete has hardened sufficiently, the concrete and reinforcement merge to create a panel which can be removed from the mold in a conventional manner. This panel is generally similar, exteriorly, to the prior art panel of  FIGS. 1-3 . However, with reference to  FIG. 23 , which shows an exemplary panel, the panel will be seen to have increased concrete cover as compared to the prior art, specifically 55 mm, as indicated by dimension B 2 . It will be recalled that dimension B 1  in the prior art was 42-45 mm. An advantage of the increased concrete cover is increased impermeability of the concrete slab resulting in a structure with an extended operational life and, in some jurisdictions, the ability to omit the use of a protective topping on the concrete surface, which significantly reduces lifetime maintenance costs. 
         [0121]    In the jurisdiction of Ontario, Canada, for example, a parking garage structure of the general type in question, with concrete coverage of only 42-45 mm, would likely be required to have a waterproofing coating applied every 2-5 years, adding greatly to lifetime structure costs over 55 mm coverage structures, which would not be subject to this obligation. 
       Structure 
       [0122]    Panels according to the present invention can, surprisingly, notwithstanding the absence of the conventional second layer of reinforcement, be assembled into a useful modular structure in the conventional manner previously described. 
         [0123]      FIG. 25  is a view similar to  FIG. 13 , but showing the structure of the present invention, and for comparison, is illustrated next to  FIG. 24 , which is a view identical to  FIG. 13 . 
         [0124]    For clarity, the various dimensions of the structures in  FIG. 24  and  FIG. 25  are set out below, in mm: 
         [0000]    
       
         
               
               
               
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 FIG. 24 
                 A1 = 103 
                 B1 = 42-45 
                 C1 = 10 
                 D1 = 50 
                 E1 = 75 
                 F1 = 13 
                 G1 = 10 
               
               
                 FIG. 25 
                 A2 = 105 
                 B2 = 55 
                 C2 = 19 
                 D2 = 39 
                 E2 = 80 
                 F2 = 29 
                 G2 = 10 
               
               
                   
               
             
          
         
       
     
         [0125]    From this, it will be understood that the panel of the present invention has beam overlap of 19 mm, as indicated by dimension C 2 , a significant increase over the 10 mm overlap C 1  of the prior art. The concrete slab of the present invention also has increased Nelson stud rise F 2  of 29 mm as compared to prior art F 1  rise of 13 mm. 
         [0126]    Without intending to be bound by theory, it is believed that these dimensional differences enable structures according to the present invention to be built with less reinforcement than structures of the prior art. 
         [0127]    The stronger structure may be the result of less Nelson stud flexion, due to the lower positioning D 2  of the u-shaped rebar element and increased offset F 2 ; and/or increased lateral reaction forces, due to increased stud penetration E 2  in the grouted gaps. 
         [0128]    The increased overlap C 2  provides additional tolerance in construction, and has some advantage in terms of reduced grout leakage, associated with the lengthened leak path. 
         [0129]    Whereas but various exemplary embodiments have been herein described, it will be evident that numerous variations are possible therein. 
         [0130]    Importantly, whereas a panel is shown in  FIG. 24  which has concrete cover of 55 mm, cover could be increased to 59 mm in a panel of the same thickness by lowering the reinforcement mat by 4 mm. This would still leave 30 mm bottom concrete ‘coverage’, a requirement in some jurisdictions for steel reinforced structures. 
         [0131]    Of course, if the reinforcement was lowered by 4 mm, the thickness of the panel could be reduced by 4 mm, i.e. to 101 mm, while still leaving 55 mm top cover. Bottom coverage could be increased further by adding additional concrete; the panel thickness could readily be increased by 21 mm, to a total of 126 mm, which would result in bottom coverage of 55 mm and top coverage of 55 mm. Top coverage could also be increased. Additional bottom coverage could be advantageous in some applications for soundproofing purposes. Additional top cover could increase lifespan and be advantageous for soundproofing purposes. Top cover can be reduced from 55 mm, but reductions below 50 mm would be expected to have substantial disadvantage in terms of lifespan. Reductions in bottom coverage to 10 mm, with top coverage at 55 mm, would result in a 81 mm thick panel and differential elevation F 3  of 53 mm, as shown in  FIG. 26 ; in some applications, this would require suitable accommodation for fire-resistance, i.e. a sprinkler system, or accommodations for corrosion, for example, stainless reinforcement. For clarity, the dimensions of the structure shown in  FIG. 26  are, in mm: A3=81 B 3 =55 C 3 =19 D 3 =15 E 3 =80 F 3 =53 G 3 =10 
         [0132]    These variations on panel thickness and reinforcement level and type would have commensurate impacts on the differential elevation between the underside of the Nelson stud and the centerline of the hook bar; the illustrated differential of 29 mm in  FIG. 25  could readily be increased to 33 mm by a suitable lowering of the reinforcement by 4 mm. Similarly, in 105-126 mm panels, the reinforcement could be raised another 11 mm, permitting a differential elevation of 18 mm. 
         [0133]    Differential elevation can also vary with the height of the Nelson stud, which can range between 80 mm and 100 mm in the context of a parking garage structure having panels of the general type described herein. Of course, the overall thickness of the panel should be sufficient to permit the Nelson studs to be grouted over and coated. 
         [0134]    Further, whereas the illustrated panel was indicated to be 2.5 metres in width, another typical size is 2.8 metres, and it is known that panels of up to 3.0 metres in width could be used in association with the above-described panel structure [ie without changing panel thickness or reinforcement]. 
         [0135]    Similarly, whereas the illustrated panel is indicated to be 9.0 metres in length, this is a convenient length, only. Panels, of, for example, 10.0 metres in length could be manufactured. The limiting factor in terms of length is road transportation regulations and crane capacity. Shorter panels, and irregular shaped panels, could and would also be used, for ramps and other structures. 
         [0136]    Yet other variations are also possible. 
         [0137]    Accordingly, the invention should be understood as limited only by the accompanying claims, purposively construed.