Patent Publication Number: US-2007101672-A1

Title: Reinforcing elements and reinforced concrete or prestressed concrete parts produced by means of the same

Description:
The invention concerns a concrete reinforcement element according to the generic term used in Claim  1  as well as the reinforced concrete or pre-stressed concrete components made using this element according to the generic term used in Claim  30 .  
      Shear stressed reinforced concrete or pre-stressed concrete components, such as a supported reinforced concrete ceiling, require shear reinforcement in the area of columns of the ceiling to ensure shear safety.  
      Known shear reinforcement includes the following: shear reinforcements made of concrete reinforcing steel with shear reinforcement elements in the form of S-hooks (although this is no longer allowed according to DIN 1045) or stirrups, dowel bars, double headed dowels, open web girder, Tobler Walm, “Geilinger Kragen”, retaining plate mesh, “Riss Stern”, etc.  
      Shear reinforcement with reinforcement elements in the form of S-hooks or stirrups has to be encircled with a usually available flexural longitudinal reinforcement, due to bad anchorage in order to prevent the shear reinforcement being ripped out. It must be noted that this only achieves a moderate increase in the shear force resistance. The fitting of the concrete reinforcement elements is complicated and thus costly. In addition, conventional concrete reinforcement elements, such as stirrups are no longer considered fittable if exposed to high degrees of concrete reinforcement and a high proportion of shear reinforcement.  
      The alternative option is to use dowel bars, which are usually put on the lower formwork, so that—if available—the lower layer of reinforcement is encircled by a cross-section of the bar. For the load bearing capacity, however, an exact positioning and fixing of the bar is crucial, which cannot always be ensured on a construction site. The dowel bars are furthermore individually made and welded, which in proportion to the very high costs brings hardly any demonstrable improvement of the shear force resistance.  
      Joining elements or spacers for the upper and lower layers of reinforcement are known from DE-U1-71 18 881, DE-U1-298 14 923, DE-OS-2 111 243 or DE-OS-1 913 104. These elements, however, do not serve as concrete reinforcement elements; instead they fix only the reinforcement bars intended within the concrete component in a desired location or position before pouring in the concrete. This has no influence on the punching shear strength or even on the lateral load-bearing capability of the concrete ceiling.  
      Other known concrete reinforcement elements such as double headed dowels, Tobler Walm and “Geilinger Kragen” can improve the load-bearing capability or the punching shear strength of reinforced concrete or pre-stressed concrete components, in particular in the area of ceiling support. However, the lateral load-bearing capability of the concrete component is also hardly influenced through their use. Furthermore, these elements which mostly have to be produced individually on site, are characterised by a very expensive production. They are also very time-consuming both in mounting and in production, and so much time is often not available on a construction site.  
      The task of the invention is to overcome these and further disadvantages of the technical state of the art, by providing concrete reinforcement elements to be mounted in reinforced concrete or pre-stressed concrete components, which have a simple structure and are cheap to produce. Furthermore the invention aims to achieve a good anchorage of the concrete reinforcement elements between the reinforcement bars, while keeping the mounting quick and uncomplicated to execute. The concrete reinforcement elements have to improve the stability of the finished reinforced concrete or pre-stressed concrete component, in particular increasing significantly the lateral load-bearing capability of the component. The reinforced concrete or pre-stressed concrete component also has to be cheap to produce and easy to handle.  
      The main characteristics of the invention are listed in the characterising part of Claims  1 ,  27 ,  28 ,  29  and  30 . Arrangements are the subject of Claims  2  to  26  and  31  to  43 .  
      A concrete reinforcement element in the form of a bi-dimensional component, which joins together, with a continuity of strength, the upper and lower layers of the reinforcement, located on the surface of the concrete component, with suitable upper and lower retaining elements, forms the core of the invention. This significantly increases the shear force resistance of the reinforced concrete or pre-stressed concrete components.  
      The concrete reinforcement elements can be made as simple free-falling punched parts, to which further splays can be added if necessary. This enables a very cost-effective production, which has a positive effect on the production costs for the concrete components. The concrete reinforcement elements are easy to handle and quick to assemble. They simply have to be hooked in. No special knowledge or skills are required, as for example in the case of welding work.  
      The retaining elements can be realised as drilled holes, side recesses out of the bi-dimensional component and/or as splays, which encircle at least the innermost layers of each upper and lower layer of reinforcement in the case of there being more than one upper and more than one lower layer of reinforcement.  
      Surprisingly it was found that concrete reinforcement elements of this kind improve especially the shear force resistance, as well as the punching shear strength as compared to conventional structures, when they are mounted according to the invention interacting with the layers of reinforcement within a concrete component.  
      In addition to this surprising result, it was also found that a minimum thickness of the bi-dimensional components, of 1 mm for example, was sufficient when using conventional structural steel, which has a very favourable effect on production costs. 
    
    
      Further traits, details and advantages of the invention arise from the text of the claims, as well as in the following description of execution examples by means of the illustrations. They show:  
       FIG. 1 a  schematic side view of a concrete reinforcement element,  
       FIG. 2 a  schematic side view of another embodiment of a concrete reinforcement element,  
       FIG. 3  to  6  a schematic side view each of further embodiments of a concrete reinforcement element,  
       FIG. 7 a  schematic side view of a concrete reinforcement element with a securing means,  
       FIG. 8 a  schematic side view of a concrete reinforcement element with a different embodiment for a securing means,  
       FIG. 9 a  schematic side view of a concrete reinforcement element with yet another embodiment for a securing means,  
       FIG. 10  to  15  a schematic side view each of further embodiments of a concrete reinforcement element,  
       FIG. 16 a  schematic representation of a further embodiment of a concrete reinforcement element,  
       FIG. 17 a  schematic representation of a concrete reinforcement element with a indented bi-dimensional structure,  
       FIG. 18  two joined concrete reinforcement elements,  
       FIG. 19  three joined concrete reinforcement elements,  
       FIG. 20 a  different embodiment of two joined concrete reinforcement elements,  
       FIG. 21  another different embodiment of two joined concrete reinforcement elements,  
       FIG. 22 a  schematic sectional view of a concrete reinforcement element divided into two parts,  
       FIG. 23 a  schematic sectional view of a different embodiment of a concrete reinforcement element divided into two parts,  
       FIG. 24  yet another embodiment of a concrete reinforcement element divided into two parts,  
       FIG. 25 a  further variation of a concrete reinforcement element,  
       FIG. 26 a  schematic representation of a reinforced concrete or pre-stressed concrete component, 
    
    
      The concrete reinforcement element which is generally called  10  in  FIG. 1  is for use in the reinforced concrete or pre-stressed concrete component  1  (which is not represented here in any further detail). It has as its main part  12  a simple flat structure made of structural steel, which has a recess  30  each in its upper area  14  and its lower area  15 . The recess is formed by a slot, which is open to the longitudinal edge  16  on the side of the bi-dimensional structure  12 , which extends vertically from its longitudinal centre M.  
      Each recess  30  forms a retaining element  20  for the concrete reinforcement element S (which is also not shown here), in particular for a reinforcement bar of an upper and lower reinforcement layer Bo, Bu in the reinforced concrete or pre-stressed concrete component  1  (see  FIG. 26 ). These lie on each surface of the component (which is also not shown in any further detail here). They are formed by a least one inner layer Bo_y, Bu_y and at least one external layer Bo_x, Bu_x, which runs vertically to the inner layer.  
      During assembly, the bi-dimensional structure  12 , with its side-opening recesses  30 , is simply put on two reinforcement bars S of the inner layers Bo_y, Bu_y, lying directly on top of each other and running in the same direction. This means that each reinforcement bar is at least partially encircled. The clearance of the recesses  30  is calculated in such a manner that the bi-dimensional structure  12  with force transmission by friction sits tightly on the reinforcement bar S, so that it can not become loose while the concrete is poured in.  
      Hereby it is important that each concrete reinforcement element  10  always lies laterally to its bi-dimensional structure  12 , and preferably vertically to the reinforcement bars S, extending, on the whole, over the thickness of the reinforced concrete or pre-stressed concrete component  1 , namely to at least each upper and lower of the innermost of at least one inner layer Bo_y, Bu_y of the upper and lower reinforcement layers Bo, Bu. The latter are thereby bound together with a continuity of strength.  
      Comparative measurements have surprisingly shown that the concrete reinforcement element  10  according to the current invention significantly increases the punching shear strength as well as the shear force resistance of the reinforced concrete or pre-stressed concrete component  1  as compared to conventional constructions. It is sufficient here to produce the bi-dimensional structure  12 , using conventional structural steel, with a thickness of 1 mm. This has a very favourable effect on material costs.  
      A further advantage of the concrete reinforcement element  10  is that due to its simple geometry it can be made, for example, as free falling punched parts, which further lowers production costs. They are quick and uncomplicated to mount and do not require any special knowledge or skills. This also leads to a considerable reduction in production costs for the reinforced concrete or pre-stressed concrete component  1 .  
      In the embodiment of  FIG. 2  the concrete reinforcement element  10  has as a retaining element  20  in the upper area  14  a slot  30 , whereas a round or oval recess  30  is designated for the lower area  15 .  
      The embodiment of  FIG. 3  designates two slots  30  open on the side as retaining elements  20 , which run diagonally to the top at an angle α to the longitudinal centre M of the bi-dimensional structure  12 . In contrast, the shape of  FIG. 4  intends that the slots  30  run diagonally down at an angel α. In both cases putting the concrete reinforcement element  10  on the reinforcement bars S is made easier, in particular within tight spaces.  
      The concrete reinforcement elements  10  represented in  FIG. 5  has proven to have a particularly high increase in the lateral load-bearing capability of the reinforced concrete or pre-stressed concrete component  1 . Here a total of four retaining elements  20  are designated for the upper and lower areas  14  and  15  of the bi-dimensional structure  12 , namely two recesses  30  each, which are open to the longitudinal edge  16  and lie symmetrically to the longitudinal centre M.  
      Therefore, each concrete reinforcement element  10  covers in total four reinforcement bars S of the upper and lower reinforcement layers Bo, Bu, binding them together with continuing strength, which has a particularly positive effect on the lateral load-bearing capabilities of component  1 . At the same time, each concrete reinforcement element  10  is firmly anchored between the reinforcement layers Bo, Bu. It can neither mistakenly fall out, nor can it slip when the concrete is poured in. The intervals and the positions of the reinforcement layers Bo, Bu are reliably secured at all times.  
      In order to further improve the fixing of the reinforcement bars S to the retaining elements  20  or in the recesses  30 , the latter can have an extension  32  each up and down, so that in the area of the longitudinal edges  16  of the concrete reinforcement element  10  notched edges  33  are formed for the reinforcement bars S.  
      The embodiment in  FIG. 6  designates that the extensions  32  of the recess  30  in the upper area  14  of the bi-dimensional structure  12  lie across the longitudinal centre M, whereas the recess  30  in the lower area  15  is mainly L-shaped, namely with an upturned extension  32 . Here one can see that the sub-area  31  of the recess  30 , which is open to the longitudinal edge  16 , has a lower clearance than the part of the recess  30  which lies in the longitudinal centre.  
      In order to further secure the reinforcement bars S of the upper and lower reinforcement layers Bo, Bu of the concrete reinforcement elements  10 , the recesses  30  can be provided with a securing means  34 . This can, for example, be a mainly U-shaped clip made of elastic material which can be reduced breadthwise by pressure on both of its outer legs, so that it can fit into the recess  30  (see  FIG. 7 ). If the legs are released, they then lie within the walls of the slot  30  in the bi-dimensional structure  12 , so that a reinforcement bar which lies in the recess  30  can not slip out sideways.  
      In the embodiment in  FIG. 8  the securing means  34  consist of pins which are brought into the gable-end of the bi-dimensional structure  12  or onto the side mounted receptions  35 . It is advantageous to use preferably brightly coloured indicatory agents, so that the insertion of a pin  34  can be easily marked and recognised on the construction site.  
      Alternatively a rotatable pin  34  or another rotatable bolting element, as well as a positioning pin, can be arranged on the longitudinal edge  16  of the bi-dimensional structure  12 , whereby the pin  34  is turned after the concrete reinforcement element S is brought in between the concrete reinforcement element  10  and the positioning pin. The indicatory agents  36  on the pin  34  would then show all in the same direction, or indicate the same inclination or position relative to the concrete reinforcement element  10 , thus enabling a fast check of the secured condition even for a large number of concrete reinforcement elements.  
       FIG. 9  shows further advantageous embodiments for securing means  34 , for example in the form of a simple elastic element, such as a strip or a simple wedge.  
      Another important embodiment of the concrete reinforcement element  10  according to this invention is shown in  FIG. 10 . The retaining element  20  is formed by an end-sided formed simple splay  40  in the upper area  14  of the bi-dimensional structure. Preferably this will encircle a reinforcement bar S of the outer layer Bo_x of the upper reinforcement layer Bo (see  FIG. 26 , left element  10 ). The retaining element  20  in the lower area  15  of the bi-dimensional structure  12  is a L-shaped recess  30 , which encircles a reinforcement bar S of the inner layer Bu_y of the lower reinforcement layer Bu.  
      As shown by  FIG. 11  to  13 , the retaining elements  20  can be combined in almost any way in the form of recesses  30  and splays  40 , whereby reinforcement bars S of the inner or outer layers Bo_y, Bu_y, Bo_x, and Bu_x can be grasped at the same time.  
      In  FIG. 11   a  the splay  40  which is formed onto the upper area  14  is bent upwards, whereas the splay  40  in the lower area  15  points forward. The concrete reinforcement element  10  has thereby a mainly Z-shaped form in a cross-section—as can be seen in  FIG. 11   b , whereas the execution form of  FIGS. 12 and 12   a  has a U-profile in a cross-section.  
      According to  FIGS. 13   a  and  13   b  the splays  40  can be doubled or multiplied, whereby the concrete reinforcement element  10  can have an S-shape in the cross-section—as shown by  FIG. 15   b.    
      The embodiment of  FIG. 16  is based on the construction form of  FIG. 6 , that means that in the upper and lower areas  14  and  15  of the bi-dimensional structure  12  a total of four recesses  30  are intended symmetrical to its longitudinal centre as retaining elements  20 , which encircle the reinforcement bars with a continuity of form. The recesses  30  are not open to the longitudinal edges  16 , that means that the reinforcement bars S are mainly introduced vertically into the bi-dimensional structure  12 . Additional splays  40  encircle in each case the outer layer Bo_x, Bu_x of the upper and lower reinforcement layers Bo, Bu as additional retaining elements, so that the concrete reinforcement elements  10  are integrated in an optimal manner into the reinforced concrete or pre-stressed concrete component  1  for the purpose of increasing the lateral load-bearing capability. Furthermore, its ductility is also increased when there is strain on the shear force.  
      The same advantages are also found in yet another form of the concrete reinforcement element ( FIG. 17 ). Here the bi-dimensional structure  12  is indented in the cross-section, whereby the indentation  24 , formed through simple and preferably right-angled splays, is realised between the upper and lower reinforcement layers (Bo, Bu).  
      If required, the concrete reinforcement elements  10  can encircle more than four reinforcement bars S. The bi-dimensional structure  12  must correspondingly be extended horizontally to its longitudinal centre M and the required number of retaining elements  20  must be added.  
      In the embodiment of  FIG. 18  two concrete reinforcement elements  10  are arranged in longitudinal direction at least one reinforcement bar (S) next to each other in a V-shape, whereby the bi-dimensional structures in their upper areas  14  are joined to one another or are one piece.  
      The construction form of  FIG. 19  provides for many concrete reinforcement elements  10  to be standing parallel one after the other. Each bi-dimensional structure  12  is bound in a T-shape with its upper area  14  to a flat bar  26 , which protrudes over the breadth of the concrete reinforcement element  10  in order to at least partially hold or encircle an element S of the upper reinforcement layer.  
      The embodiment in  FIG. 20  is made up of concrete reinforcement elements  10  and a flat bar  26 , which together form a U-profile, whereby the latter also serves as a retaining element  20 , in that it encircles at least one reinforcement bar S of the upper reinforcement layer Bo.  
      The recesses  30  in the upper area  14  of the bi-dimensional structure  12  can also be realised in a rectangular form—as shown by  FIG. 21 —and join two parallel concrete reinforcement elements  10 , which are arranged next to each other, with a flexible spring clamp  28 , whereby the clamp  28  with its legs (which are not described in any further detail) is set in the recesses  30 , encircling also at least one reinforcement bar S of the upper reinforcement layer Bo.  
      Yet another important embodiment of the current invention can be seen in  FIG. 22  to  24 , when namely the bi-dimensional structure  12  of the concrete reinforcement element  10  is divided, vertically to its longitudinal centre M, into a lower half  50  and an upper half  60 , whereby both halves  50  and  60  are joined to each other in a separable manner.  
      Thereby it is possible, for example, to prefabricate reinforced concrete or pre-stressed concrete components, for example ceiling elements in which the lower halves  50  of the concrete reinforcement elements  10  are built or poured into the lower half of the ceiling. Therefore, on the construction site, only the missing upper reinforcement layer Bo has to be added, whereby the upper halves  60  of the concrete reinforcement elements  10  are joined to the lower half  50  which is protruding from the prefabricated ceiling component. Afterwards, the ceiling can be completed by pouring in the concrete.  
      Ceiling elements which have been prefabricated in this way have the advantage of being much easier to handle and transport, as not only do they weigh less, but also the dimensions are smaller. Furthermore it also enables more flexible arrangement possibilities on the construction site. For example the thickness of the concrete ceiling can be individually designed, by using upper halves  60  with different lengths of the concrete reinforcement elements  10 . Various retaining elements  20 , in particular also splays  40 , can be added to them in their final areas  14  and  15 .  
      The halves  50  and  60  are preferably joined by means of the hook-shaped joining elements  52  and  62 , which encircle one another with a continuity of strength and form. It is important here that the joint is constantly subjected to tension.  
      In the embodiment of  FIG. 24  the lower half  50  of the concrete reinforcement element  10  is complemented by an upper half  60  made of coiled rods  66 , whereby this is tilted in a Z-shape and can be put into an appropriate recess in the lower half  50 .  
       FIG. 25  shows two views on the broad side of a further embodiment of the concrete reinforcement element  10  according to the current invention. This embodiment is characterised by the fact that the area between the broken lines compared to the areas above or below is shifted backwards or forwards from the image plane, going in or going out against the upper and lower area. This becomes visible when viewed on the narrow edge of both components. Alternatively, component  10  can also be realised in such a way, that, for example, only an upper part is shifted against a lower part of the component, for example, by tilting or stressing.  
      Hereby, in both cases it is achieved that two such identical components  10 , if they are pushed into each other with the edges  16 , in which there are the openings of the side recesses  30 , form a dovetail and a covered area comes into being, so that both components  10  together form a recess  30 , which secures an element S, which is threaded through it, of a reinforcement layer Bo or Bu from slipping upwards or downwards. The concrete reinforcement element  10  in the middle of  FIG. 26  encircles per element S each of the outermost layers Bo_x and Bu_x of the upper and lower reinforcement layers Bo, Bu, while the concrete reinforcement element  10  represented on the right of  FIG. 26  only joins elements S of the inner layers Bo_y, Bu_y of the upper and lower reinforcement layers Bo, Bu.  
      The number and embodiment of components  10  have to be calculated according to the type of concrete used and the desired load-bearing capability, in order to achieve the necessary punching shear strength, for example in the area of a column. In each case this results in a significant increase in the shear force resistance of the component  1 .  
      The current invention is not limited to one of the aforementioned embodiments, but instead can be varied and altered in many different ways. The concrete reinforcement elements can, for example, be fabricated from other materials such as steel sheeting, plastic or composite material. One can also extend the concrete reinforcement elements  10  or their bi-dimensional structure  12  horizontally to their longitudinal centre M, in order to be able to encircle several reinforcement bars S of the upper and lower reinforcement layers Bo, Bu simultaneously. It is important here as well that the concrete reinforcement elements  10  are always simple, flat sheet metal components, if necessary tilted at the ends or in the middle, featuring retaining elements in the upper and lower areas which receive or encircle the reinforcement bars S of the upper and lower reinforcement layers Bo, Bu. Mounting is achieved without any complex welding or assembly work, whereby the upper and lower reinforcement layers Bo, Bu are pulled tight by the concrete reinforcement elements  10 , joining them with a continuity of strength.  
      All of the traits and advantages in the claims, description and the illustrations, including constructive details, spatial arrangements and procedural steps can be essential to the current invention on there own or various different combinations.  
     LIST OF REFERENCE NUMERALS  
     
         
          α Angle  
          Bo, Bu Reinforcement layer  
          Bo_y, Bu_y Inner layer  
          Bo_x, Bu_x Outer layer  
          M Longitudinal centre  
          S Concrete reinforcement element  
           1  Reinforced concrete or pre-stressed concrete component  
           10  Concrete reinforcement element  
           12  Main component  
           14  Upper area  
           15  Lower area  
           16  Longitudinal edge  
           20  Retaining elements  
           24  Indentation  
           26  Flat bar  
           28  Clamp  
           30  Recess  
           31  Sub-area  
           32  Extension  
           33  Notched edge  
           34  Securing means  
           35  Reception  
           36  Marking  
           40  Splay  
           50  Lower half  
           52  Joining element  
           60  Upper half  
           62  Joining element  
           66  Coiled rods