Abstract:
The present invention broadly comprises a method and apparatus for constructing a concrete lower. In one embodiment, a tower construction apparatus includes an alignment jig and a pre-cast concrete element located on the alignment jig.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Application No. 62/168,203, filed May 29, 2015, the entire content of which is incorporated into the present application by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a method and apparatus for constructing a concrete tower. In particular, the invention relates to constructing a concrete tower using pre-cast concrete components. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventional methods and apparatuses for constructing a tower with pre-cast components can be labor intensive. Accordingly, a need for a more efficient method and apparatus has been developed by the present inventors. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention broadly comprises a method and apparatus for constructing a concrete tower. In one embodiment a tower construction apparatus includes an alignment jig and a pre-cast concrete element located on the alignment jig. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0006]      FIG. 1  illustrates an embodiment of a concrete tower that can be constructed according to an exemplary embodiment of the present invention; 
           [0007]      FIG. 2  illustrates close up view of portions of the concrete tower in  FIG. 1 ; 
           [0008]      FIGS. 3 and 4  illustrate a first exemplary process for making subassemblies for the tower shown in  FIG. 1 ; 
           [0009]      FIGS. 5-9  illustrate a second exemplary process for making subassemblies for the tower shown in  FIG. 1 ; 
           [0010]      FIGS. 10-14  illustrate an exemplary process for stacking the subassemblies for the tower shown in  FIG. 1   
           [0011]      FIG. 15  illustrate several views of the element that make up the subassemblies; 
           [0012]      FIG. 16  shows an embodiment of a form for creating the elements that make up the subassemblies; 
           [0013]      FIG. 17  illustrates exemplary structures for joining the pieces; and 
           [0014]      FIGS. 18-21  show multiple embodiments of towers made in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    Reference is presently made in detail to exemplary embodiments of the present subject matter, one or more examples of which are illustrated in or represented by the drawings. Each example is provided by way of explanation of the present subject matter, not limitation of the present subject matter. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present subject matter without departing from the scope or spirit of the present subject matter. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present subject matter covers such modifications and variations as come within the scope of the disclosure and equivalents thereof. 
         [0016]      FIG. 1  shows a tower  10  built according to one embodiment of the present invention. Tower  10  includes a foundation  20 , a concrete portion  30 , a metal portion  40 , and a wind turbine  50 . However, towers used for purposes other than supporting wind turbines may be built in accordance with the present invention, and towers without any metal portion may also be built according to the present invention. Such modifications are within the scope of the invention as claimed. 
         [0017]    As shown in  FIG. 2 , the embodiment of the tower  10  shown in  FIG. 1  may include a concrete portion  30  including sections  32 . In one embodiment, each section  32  is made of two precast elements,  33 A and  33 B. However, each section may be made of more than two elements. Concrete portion  30  also includes a transition region  38  in contact with the bottom of metal portion  40 . Transition region  38  may include a precast transition ring  39  including a plurality of apertures  39 A through which post tensioning strands  22  pass through. Post tensioning strands may be anchored in the foundation  20  and are capped off as they pass through apertures  39 A. 
         [0018]    In another embodiment, a post-tensioning strand  22  is inserted into one of apertures  39 A and ted through the aperture until it reaches the foundation level. An elbow passageway  24  in the foundation  20  (shown in  FIG. 10 ) then guides the post-tensioning strand  22  up an adjacent aperture  39 A. When the strand front end reaches the top of the adjacent aperture  39 A, the strand is cut and each end is anchored on the top of transition ring  39  as shown in  FIG. 2 . 
         [0019]    Transition ring  39  may also include a plurality of post tensioning nods  39 B. These rods  39 B extend through passages in transition ring  39  and a bottom flange of metal portion  40 , and are capped off just above the flange of metal portion  40  and just below the surface of transition ring  39 . This fixes the metal portion  40  to the concrete portion  30 . 
         [0020]      FIGS. 3 and 4  show a first embodiment for assembling sections  32 . In  FIGS. 3 and 4 , each section  32  is made of two elements  33 A and  33 B which are sealed together at the factory. The sealed sections  32  are then transported to the worksite by truck  60 A. As shown in  FIG. 4 , second section  32 B may be connected to first section  32 A while first section  32 A is still located on truck  60 A to create subassembly  34 . Subassembly  34  may then be moved onto foundation  20  using a crane (not shown). In the embodiment shown in  FIG. 4 , second section  32 A is rotated with respect to section  32 A before connection such that the joints between the elements of each section do not line up, but are 90 degrees from each other. This is done for each succeeding section, as shown in  FIG. 1  to provide additional structural strength. 
         [0021]    In another embodiment, each section is made of two elements that are transported from the factory separately and then assembled at the worksite. This embodiment is shown in  FIG. 5-9 .  FIG. 5  shows truck  60 A with alignment jig  62  mounted on the trailer of the truck  60 A. First element  33 A is brought in by truck  60 B, and element  32 A is moved onto alignment jig  62  using a crane (not shown).  FIG. 6  shows truck  60 C bringing second element  33 B, which is also moved onto jig  62  and then attached to element  33 B to create a first section  32 A. 
         [0022]      FIG. 7  shows truck  60 D bringing element  33 C, which is then stacked onto first section  32 A by a crane (not shown). Element  33 C is placed such that approximately half of element  33 C is located on element  33 A and half on element  33 B. This ensures that the joints between the two sections in the subassembly will be rotated by 90 degrees with respect to each other, as noted above.  FIG. 8  then shows element  33 D on truck  60 E for completion of subassembly  34 .  FIG. 9  shows completed subassembly  34 , along with a close up of the connection between the sections. Rods  35  are used to secure the sections together. 
         [0023]      FIG. 10  shows subassembly  34 A next to foundation  20 . Subassembly  34 A is moved onto foundation  20  by a crane (not shown).  FIG. 11  shows subassembly  34 B is then brought to foundation  20  so that subassembly  34 B can be stacked on subassembly  34 A. The subassemblies are stacked such that joints between elements in consecutive sections do not line up.  FIG. 12  shows subassembly  34 C ready to be stacked onto subassembly  34 B. Each succeeding subassembly may also have a tapering width, such that the tower becomes narrower as it gets higher.  FIGS. 13 and 14  show subassemblies  34 D and  34 E, which again are successively stacked on foundation  20  to form concrete portion  20  of tower  10 . 
         [0024]      FIG. 15  shows one embodiment of the elements  32 . Elements  32  include ducts  37  through which post-tensioning strands  22  pass. They also include openings  36  through which rods  35  pass. Alignment jig may include pegs  63  (labeled in  FIG. 5 ) which enter openings  36  and ducts  37  to hold the elements  32  on the jig  62 . 
         [0025]      FIG. 36  shows an embodiment of a form  70  for creating elements  32 . In this embodiment, the arms of the element  32  are facing down. However, alternate embodiments forming the element in any configuration are also within the scope of the invention. 
         [0026]      FIG. 17  shows two exemplary embodiments for fastening the elements  32  together. In each of the embodiments shown, rebar  80 A and  80 B extend from the opposing ends of the adjacent elements into an open space. One side of the open space is sealed with a caulked joint  82 . The other side of the open space is sealed with plate  84 . The open space is then filled with a grout to join the elements together. 
         [0027]    In another embodiment, the elements in a section may be joined with a grout joint as shown in  FIG. 17  on one side of the section  32 , but only sealed with a waterproof adhesive on the other side. Thus, only the grout joint will bear any significant load, as the waterproof adhesive cannot bear any significant structural load. This may be done because structural connections between joints are required to be certified, which is both costly and time consuming. Structural connections must be able to withstand compression, tension and shear loads, with a minimum factor of safety. In an exemplary embodiment, the number of areas which need to be certified is advantageously minimized. The grouted joints are structurally fastened together, but the adhesive joints have no structural connection between elements. Further, the sections  32  are rotated such that the adhesive joints are staggered as you go up the tower. That is, the adhesive joint tor two consecutive sections  32  are not facing the same direction. This provides further structural strength for the tower. 
         [0028]      FIGS. 18-21  shows a plurality of configurations that can be made in accordance with the present invention.  FIGS. 18 and 19  show towers with 15 sections  32 , some of which taper and some of which have straight sides.  FIG. 20  shows a tower with 15 sections  32  and a tower with 18 sections  32 .  FIG. 21  shows three exemplary tower configurations, one with 15 sections  32 , one with 18 sections  32 , and one with 28 sections  32 . All of these embodiments are within the scope of the invention as claimed. 
         [0029]    The present written description uses examples to disclose the present subject matter, including the best mode, and also to enable any person skilled in the art to practice the present subject matter, including making and using any devices or systems and performing any incorporated and/or associated methods. While the present subject matter has been described in detail with respect to specific embodiments thereof it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rattier than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.