Patent Publication Number: US-9404254-B2

Title: Post-tension concrete leave out splicing system and method

Description:
FIELD 
     This description relates generally to floor construction using post-tensioned concrete slabs. 
     BACKGROUND 
     Generally, a process for new floor construction using post-tensioned concrete slabs requires a gap (also known as a leave out, a pour strip out, etc.) that separates adjacent concrete slabs (also known as pours or castings). Generally, the gap is four feet and more in length. That is, several feet in distance separates the two ends of the post-tensioned concrete slabs. Sometimes the gap distance (the distance which separates the two ends of the post-tensioned concrete slabs) may be called a “width,” but for clarity and consistency, the term “width” is used herein to describe the distance along the direction labeled “W,” and the term “length” is used herein to describe the distance along the direction labeled “L” (e.g., see  FIGS. 1-3 ). Accordingly, ΔL is used herein to describe a change in distance along the “L” axis direction. Generally, the gap is filled in (i.e., lap spliced) with a pour strip at a later time, connecting the slabs together to form the entire floor. 
     Prestressed concrete is a type of reinforced concrete which has been subjected to external compressive forces prior to the application of load. Prestressed concrete is categorized as either pre-tensioned or post-tensioned. 
     Pre-tensioned concrete is formed by a process including initial stressing of a wire strand system and then casting concrete around the stressed wire strand system. The stress from the wire strand system transfers to the concrete after the concrete has reached a specified strength (e.g., cured to a set specification). 
     Post-tensioned concrete is formed by a process of casting wet concrete around an unstressed wire strand system and then stressing the wire strand system after the concrete has reached specified strength (e.g., cured to a set specification). For example, post-tensioned concrete can have a wire strand system which has a wire enclosed in a duct (e.g., pipe, conduit, etc.). Concrete is formed around the duct and the concrete sets and cures. Then, the wire is stressed and grout material (e.g., a mixture of cement, sand, aggregate, and water) is pumped into the cavity surrounding the wire. The grout material bonds the wire to the duct, and the duct is bonded to the cured concrete. Thus, the stress applied to the wire can be transferred to the concrete. The applied stress (e.g., forces applied to the wire strand system) in the post-tensioning process causes a volume change (and/or a length change) to the concrete material. The volume change of the concrete material causes a change in the length of the concrete slab. The length change is a shortening in the direction parallel to applied stress (e.g., the post-tensioning force). 
       FIGS. 1-2  show schematic diagrams of a floor construction  10  according to a generally known process using post-tensioned concrete.  FIG. 1  shows a top-down plan view of the floor construction  10 . The floor construction  10  includes post tensioned slabs  12 ,  14  separated by a gap  16 .  FIG. 1  shows the “width” direction indicated by “W” and the “length” direction indicated by “L” ( FIGS. 2 and 3  also show the length direction indicated by “L”).  FIG. 2  shows a side view of the floor construction  10 , also showing the slabs  12 ,  14 , and the gap  16 . The floor construction  10  is made by a process wherein the post tensioned slabs  12 ,  14  are each poured separately, tensioned independent of each other after they have sufficiently cured. Thus, the rebars in the post-tensioned slab  12  do not necessarily lineup (e.g., axially) with the rebars in the post-tensioned slab  14 . 
     Each of the slabs  12 ,  14  changes volume due to their tensioning processes. The typical tensioning process for a typical floor construction uses the gap  16 , which is typically four to eight feet in length, for accommodating appropriate tooling and equipment (and also for access by workers) to tension the slabs  12 ,  14 . Further, the gap  16  (i.e., the separation between the two slabs  12 ,  14 ) becomes longer (e.g., along direction L shown in  FIG. 1 ) during and after the tensioning of one or both of the slabs  12 ,  14 . That is, the volume changes in the slabs  12 ,  14  and the slabs  12 ,  14  become shorter. And because the slabs  12 ,  14  become shorter, the separation between them, which is the gap  16 , becomes longer. 
     For example, in a typical hotel floor construction, the gap  16  can be about sixty to seventy feet in width and four to eight feet in length. Generally, the gap  16  is left open for twenty to thirty days to allow most of the volume changes (i.e., slab shortening) to occur to the post-tensioned concrete slabs  12 ,  14 . After the twenty to thirty days, the gap  16  is filled in (i.e., lap spliced) with a pour strip  18  to provide a structural continuity of the floor construction  10  required by the final design to resist all required loads. 
       FIG. 3  shows a close-up schematic view of a portion  20  of the floor construction  10  shown in  FIG. 2 . The portion  20  shows the first slab  12  having a post-tensioning wire strand system  22  for stressing the concrete  23 . The slab  12  includes a steel reinforcing bar  24  (also known as rebar) which reinforces the concrete  23  in the slab  12 . Generally, the rebar  24  and other rebar in the slab  12  are somewhat regularly positioned in the slab  12 , and extend out from the end of the slab  12  towards the gap  16 . The second slab  14 , which is also shown in the portion  20 , has its own post-tensioning wire strand system  26  for stressing the concrete  27 . The slab  14  includes a rebar  28  which reinforces the concrete  27  in the slab  14 . Generally, the rebar  28  and other rebar in the slab  14  are somewhat regularly positioned in the slab  14 , and extend out from the end of the slab  14  towards the gap  16 . In the prior art process of forming the floor construction  10 , the positioning of the rebar  28  is not based on or with respect to the position of the rebar  24 . Further, prior to the filling in of the gap  16  with the pour strip  18 , the rebar  24  extending out from the slab  12  is not connected to the rebar  28  extending out from the slab  14 . That is, prior to the filling in of the gap  16  with the pour strip  18 , the rebar  24  extending out from the slab  12  is not directly connected to the rebar  28  extending out from the slab  14 . That is, prior to the filling in of the gap  16  with the pour strip  18 , the rebar  24  extending out from the slab  12  is not indirectly connected to the rebar  28  extending out from the slab  14 . Other rebar (s)  30  is(are) positioned, or laid down, inside the gap  16  along the width direction, so that the other rebar(s)  30  is(are) perpendicular to the length direction of the rebar  24  and/or  28 . Then, the pour strip  18  is formed around the rebar  24 ,  28 ,  30  filling in the gap  16 . 
     Referring back to  FIG. 1 , in a multi-level building construction having one or more floors, the floor construction  10  can be placed above another floor. These floors are connected to and accessible via a construction elevator  30 . Generally, there is only one (or very few) construction elevator  30  that is used during the construction of the building. Accordingly, during the construction of the floor construction  10 , the slab  12  area can be accessed via the elevator  30 . However, the slab  14  area cannot be accessed easily when a gap  16  four feet and more exists between the slabs  12 ,  14 . That is, construction equipment cannot easily be moved to slab  14  from slab  12 . Thus, generally, the construction process requiring access to slab  14  waits the twenty to thirty days until the pour strip  18  is poured to splice the slabs  12 ,  14  together. Further, the gap  16  allows significant weather conditions to intrude into the floor beneath the floor construction  10 . Such weather conditions can also prevent work from being performed in the floor underneath the floor construction  10 . Despite these disadvantages of having long gaps in post-tension concrete construction, waiting and time delay are generally an accepted part of the-process in the field of construction. 
     BRIEF SUMMARY 
     Devices, systems, and methods for connecting post-tensioned concrete slabs in new floor construction reduce the distance (e.g., length) of the gap between the post-tensioned concrete slabs as compared to conventional construction. Accordingly, the devices, systems, and methods disclosed herein advantageously reduce project construction time by reducing the time delay in accessing the floor underneath the slabs due to, for example, safety and/or weather conditions. 
     An embodiment of concrete construction (e.g., a new floor construction) includes a first post-tensioned concrete slab and a second post-tensioned concrete slab, said first post-tensioned concrete slab and said second post-tensioned concrete slab having respective upper surfaces that are generally aligned, said first post-tensioned concrete slab including a first rebar installed therein, said second post-tensioned concrete slab including a second rebar installed therein, said first post-tensioned concrete slab and second post-tensioned concrete slab being separated by a gap so that the concrete material of said first post-tensioned concrete slab is not in contact with the concrete material of said second post-tensioned concrete slab, said construction comprises a splice device positioned in the gap splicing together a portion of the first rebar and a portion of the second rebar. 
     In an embodiment of the concrete construction, said splice device includes a cavity that contains said end portion of the second rebar. In an embodiment of the concrete construction, said cavity also contains said end portion of the first rebar. In an embodiment of the concrete construction, said cavity does not contain said end portion of the first rebar. In an embodiment of the concrete construction, said splice device is connected to said end portion of the first rebar. In an embodiment of the concrete construction, said splice device is connected to said end portion of the first rebar at an end of said splice device, wherein said end has a threaded surface which mates with a threaded surface of said end portion of the first rebar. In an embodiment of the concrete construction, said splice device is connected to said first rebar by a weld. In an embodiment of the concrete construction, said splice device is connected to said second rebar by a weld. In an embodiment of the concrete construction, the concrete material of said first post-tensioned concrete slab is not in contact with the concrete material of said second post-tensioned concrete slab. 
     In another embodiment of the concrete construction, the gap has a longer dimension for one side-to-side and a shorter dimension for another side-to-side, the shorter dimension (e.g., along the “L” direction of the floor construction shown in  FIG. 4 ) being three feet or less, preferably two feet or less, or more preferably twelve (12) inches or less along the length. In all of the embodiments, the minimum distance of the gap that can be achieved is the length of the splice device used in the gap. 
     In an embodiment of the concrete construction, said splice device splices together the first rebar and the second rebar so that said first rebar and the second rebar are parallel with each other. In an embodiment of the concrete construction, said splice device splices together the first rebar and the second rebar so that said first rebar and the second rebar are inline. 
     In an embodiment of the concrete construction, a strip of non-shrink material is placed in the gap, wherein said strip has a compressive strength that is greater than or equal to the compressive strength of the concrete material of said first post-tensioned concrete slab and/or the concrete material of said first post-tensioned concrete slab. 
     In an embodiment of the concrete construction, the strip of non-shrink material completely surrounds the splice device. In an embodiment of the concrete construction, the strip has a longer dimension for one side-to-side and a shorter dimension for another side-to-side, the shorter dimension (e.g., along the “L” direction of the floor construction shown in  FIG. 4 ) being three feet or less, preferably two feet or less, or more preferably twelve (12) inches or less along the length. In all of the embodiments, the minimum distance of the strip that can be achieved is the length of the splice device used in the gap, and covered by the strip. 
     In an embodiment of a method for making a concrete construction including a first post-tensioned concrete slab and a second post-tensioned concrete slab separated by a gap, the method comprises forming said first post-tensioned concrete slab, wherein said first post-tensioned concrete slab includes a first rebar installed therein; prior to pouring a second concrete slab, positioning a second rebar for said second concrete slab so that a portion of said second concrete slab is generally in line with a portion of said first rebar; pouring said second concrete slab; forming a second post-tensioned concrete slab by tensioning said second concrete slab, thus forming said gap between said first post-tensioned concrete slab and said second post-tensioned concrete slab, wherein said gap has a longer dimension for one side-to-side and a shorter dimension for another side-to-side; positioning a splice device to contact both a portion of said first rebar and a portion of said second rebar; and securely connecting said splice device to said end portion of said second rebar. 
     In an embodiment of the method for making a concrete construction including a first post-tensioned concrete slab and a second post-tensioned concrete slab, the method comprises forming said first post-tensioned concrete slab, wherein said first post-tensioned concrete slab includes a first rebar installed therein; before a second post-tensioned concrete slab has been formed, positioning a splice device at an end portion of the first rebar, but not securely connecting said splice device to an end portion of the first rebar; before the second post-tensioned concrete slab has been formed, positioning an end portion of a second rebar inside a chamber of said splice device, but not securely connecting said splice device to an end portion of the second rebar; forming said second post-tensioned concrete slab so that said second rebar is installed therein, wherein said first post-tensioned concrete slab and second post-tensioned concrete slab are separated by a gap so that the concrete material of said first post-tensioned concrete slab is not in contact with the concrete material of said second post-tensioned concrete slab, and said end portion of said second rebar is allowed to move with respect to the splice device during the creating of said second post-tensioned concrete slab; and securely connecting said splice device to said end portion of said first rebar and said end portion of said second rebar. 
     In another embodiment of the method, said gap is formed so that the gap has a longer dimension for one side-to-side and a shorter dimension for another side-to-side, the shorter dimension (e.g., along the “L.” direction of the floor construction shown in  FIG. 4 ) being three feet or less, preferably two feet or less, or more preferably twelve (12) inches or less along the length. 
     In an embodiment of the method, the process further includes forming a strip of material in said gap with a non-shrink material, wherein said strip has a compressive strength that is greater than or equal to the compressive strength of the concrete material of said first post-tensioned concrete slab and/or the concrete material of said first post-tensioned concrete slab. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-2  show plan and elevation schematic diagrams, respectively, of a floor construction according to a generally known process using post-tensioned concrete. 
         FIG. 3  shows an enlarged, elevational schematic view of a portion of the floor construction shown in  FIG. 2 . 
         FIGS. 4-5  show plan and elevation schematic diagrams, respectively, of a floor construction according to an embodiment of the present invention. 
         FIG. 6  shows a schematic side view of a floor construction according to an embodiment of the present invention. 
         FIG. 7  shows a schematic side view of an embodiment of a floor construction according to an embodiment of the present invention. 
         FIG. 8  shows a flow chart of an embodiment of a process for constructing the floor construction with reduced gap design. 
         FIGS. 9-14  show schematic side views of floor constructions being constructed according to an embodiment of the process. 
         FIG. 15  shows a flow chart of an embodiment of a process for constructing the floor construction with reduced gap design. 
         FIGS. 16-20 and 22  show schematic side views of floor constructions being constructed according to an embodiment of the process.  FIG. 21  shows a cross-sectional view of the floor construction shown in  FIG. 20 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. Systems, methods, and devices disclosed herein are directed towards reducing the gap between post-tensioned concrete slabs in a floor construction, so that time delay caused by the existence of conventional gaps in the floor construction can be reduced and/or eliminated. 
       FIGS. 4-5  show schematic diagrams of a floor construction  100  according to an embodiment.  FIG. 4  shows the “width” direction indicated by “W” and the “length” direction indicated by “L” ( FIGS. 5-7, 9-14, 16-20, and 21  also show the length direction indicated by “L”). The floor construction  100  includes post-tensioned concrete slabs  102 ,  104 .  FIG. 4  shows a top-down plan view of the floor construction  100 . The floor construction  100  includes post tensioned slabs  102 ,  104  separated by a gap  106 .  FIG. 5  shows a side view of the floor construction  100 , also showing the slabs  102 ,  104 , and the gap  106 . The distance of the gap  106  is substantially less than the conventional gap. For example, it is possible that the gap  106  is less than three feet in distance. In a preferred embodiment, the gap  106  is a foot or less in distance. In all of the embodiments, the minimum distance of the gap  106  is the length of the splice device (e.g.,  206  shown in  FIG. 7 ) because the splice device must be placed in the gap  106 . 
     Accordingly, the floor construction  100  can advantageously reduce the overall construction time of the construction project associated with the floor construction  100 , because the time delay in accessing the floor underneath the floor construction  100  due to, for example, safety and/or weather conditions, is substantially reduced or eliminated. Further, in a multi-level building construction having one or more floors, the floor construction  100  can be placed above another floor. These floors are connected to and accessible via a construction elevator  108 . Accordingly, during the construction of the floor construction  100 , the slab  104  area can be accessed via the elevator  108  because the gap  106  has a distance that is small (or short) enough that the gap  106  can be crossed over, and/or the gap  106  can be covered with small piece of material such as, for example, a sheet of metal or a plank of wood, to serve as a short bridge between the slabs  102 ,  104 . Accordingly, the construction equipment can be easily moved between slab  104  and slab  102 . Thus, the generally required twenty to thirty day waiting period for accessing areas of the floor that cannot be reached due to the conventional gap ( 16  shown in  FIG. 1 ) can be eliminated. In a multi-level building construction and/or very large building construction having large square footage floors, the reduction or elimination of the twenty to thirty day waiting period per gap compounds to an enormous reduction in the overall construction time required for the project. 
     Further, the gap  106  can substantially reduce or prevent weather conditions to intrude into the floor beneath the floor construction  100 . Thus, weather conditions no longer prevent work from being performed in the floor underneath the floor construction  100 . Therefore, waiting and time delay associated with weather conditions can be reduced or eliminated from the construction process. 
       FIG. 6  shows a schematic side view of a floor construction  200  according to an embodiment. The floor construction  200  includes a floor  202  formed by joining two post-tensioned concrete slabs with a pour strip filled into a gap between the two post-tensioned concrete slabs. The first post-tensioned concrete slab includes at least one rebar  204  that is fixed with respect to a splice device  206 . Preferably, the splice device  206  is less than a foot in length. The second post-tensioned concrete slab includes another rebar  208  that is fixed with respect to the splice device  206 . The rebars  204 ,  208  can be aligned substantially parallel with each other and/or aligned to be continuous along the length (axial) direction. Although not shown in the schematic view, it will be understood that the floor construction  200  can include a plurality of rebars in the first post-tensioned concrete slab, wherein each of the rebars is fixed with respect to splice devices. Further, a plurality of rebars in the second post-tensioned concrete slab are each fixed with respect to the respective splice device, so that each splice device fixes a rebar of the first post-tensioned concrete slab with respect to a rebar of the second post-tensioned concrete slab. 
       FIG. 7  shows a schematic side view of an embodiment of a floor construction  300 , which is similar to the floor construction  200  shown in  FIG. 6 . The floor construction  300  has similar components as the floor construction  200  of  FIG. 6 . The floor construction  300  includes the first post-tensioned concrete slab  302  and the second post-tensioned concrete slab  304 , and the pour strip  306  filled into the gap  308  that is between the two post-tensioned concrete slabs  302 ,  304 . The splice device  206  is positioned in the gap  308 , so after the pour strip  306  is used to fill in the gap  308 , the splice device  206  becomes surrounded by the pour strip  306 . 
       FIG. 8  shows a flow chart of an embodiment of a process  400  for constructing the floor construction with reduced gap design. The process includes a step  402  of forming a first concrete slab for post-tensioning, wherein the first concrete slab includes one or more rebars. Ends of the rebars are positioned to extend out from an edge of the first slab. It is preferable that these ends of the rebars do not extend more than six inches beyond the edge of the first slab. The process includes a step  404  of positioning a splice device at the end of the rebar. Preferably, a splice device is positioned at each of the ends of the rebars that are exposed in the gap. The positioning of the one or more splice devices can be done before or after the first concrete slab has shortened along the length direction of the rebar due to tensioning of the concrete slab. If desired, the splice devices can be connected, attached, and/or fixedly secured to the rebars of the first slab at this time. This particular step can depend on the particular features of the splice device used. 
     The process further includes a step  406  of positioning the rebars for the second concrete slab so that their ends are positioned within respective inner chambers of the splice devices prior to pouring the concrete for the second concrete slab. These rebars are positioned so that they can move with respect to the splice devices. That is, the rebars for the second concrete slab are not secured to the splice devices at this stage of the process. It is preferable that the positioning of the rebars for the second concrete slab with respect to the splice devices are done after the first concrete slab has been tensioned (e.g., using the wire strand system that is included in the first concrete slab) and has gone through the volume change, becoming the first post-tensioned concrete slab. Thus, the positioning of the splice devices and then the positioning of the rebars for the second concrete slab can be done with a desired gap space in mind. That is, after the first post-tensioned concrete slab has formed, the length change along the length direction of the rebars would have been completed. Thus, when the splice devices are attached to the rebars of the first post-tensioned concrete slab, the length of the gap can be estimated and/or substantially determined. It is preferable that this estimated and/or substantially determined gap distance is less than a foot. Further, at this stage in the process  400 , the splice devices are positioned where the gap between the first and second concrete slabs will exist when the second concrete slab is formed. 
     The process includes a step  408  of pouring and forming the second concrete slab. The second concrete slab includes one or more rebars that have been positioned with the splice devices. Then, the second concrete slab is allowed to shorten along the length direction of the rebar by and due to tensioning of a wire strand system in the second concrete slab. Because the rebars for the second concrete slab are not secured to the splice devices during step  410 , the rebars can and do move with respect to the splice devices during the tensioning of the second concrete slab. 
     After the volume changes due to tensioning of the second concrete slab has been completed, the second concrete slab is the second post-tensioned concrete slab. The process  400  includes a step  412  of connecting and/or securing the rebars of the second post-tensioned concrete slab to the splice devices. In addition, if in the step  404  of connecting the splice device to the rebar of the first concrete slab, the splice device was not secured to the rebar of the first concrete slab, then, in step  412 , the splice device can be secured to the first rebar of the first post-tensioned concrete slab. Accordingly, in the step  412 , both of the first and second rebars of the first and second post-tensioned concrete slabs can be secured (e.g., connected) to the splice device. This particular step can depend on the particular features of the splice device used. 
     At this stage in the process, the gap between the first post-tensioned concrete slab and the second post-tensioned concrete slab is generally fixed. Accordingly, the gap distance is generally known. The gap distance of three feet or less is possible. Preferably, the gap distance at this stage is one foot or less. 
     The process  400  includes a step  414  of filling in the gap between the first and second post-tensioned concrete slabs with material to form a pour strip. When the pour strip is formed in the gap, the splice devices connected to the rebars of the first and second post-tensioned concrete slabs are covered by the pour strip. It is preferable that the splice devices positioned in the gap are completely covered by the pour strip. 
       FIGS. 9-14  show schematic side views of floor constructions  500   a - f , respectfully, being constructed according to the process  400  described above and shown in  FIG. 8 . Like elements are referred to with the same reference numerals. 
       FIG. 9  shows the floor construction  500   a , wherein a first concrete slab  502  is formed with rebars  506 ,  508  therein (see step  402  in the process  400  of  FIG. 8 ). End portions of the rebars  506 ,  508  are positioned to extend beyond the first concrete slab  502  at a location  510  where a gap will exist when a second concrete slab is formed. 
       FIG. 10  shows the floor construction  500   b , wherein the first concrete slab ( 502  shown in  FIG. 9 ) has been tensioned and has become a first post-tensioned concrete slab  504 . The volume of the first post-tensioned concrete slab  504  has changed from the volume of the first concrete slab ( 502  shown in  FIG. 9 ), and a length of the first concrete slab along the length direction of the rebars  506 ,  508  has been reduced by the tensioning, indicated by ΔL 1 . Near or at the ends of the rebars  506 ,  508  at the location  510  where the gap will exist when a second concrete slab is formed, splice devices  512 ,  514  are positioned at the ends of the rebars  506 ,  508  (see step  404  in the process  400  of  FIG. 8 ). 
       FIG. 11  shows the floor construction  500   c , wherein additional rebars  516 ,  518  of the second concrete slab  520  are positioned in the location  510 , and also positioned with respect to the respective splice devices  512 ,  514  (see step  406  in the process  400  of  FIG. 8 ). The rebars  516 ,  518  can be aligned in a length direction of the rebars  506 ,  508  guided by the splice devices  512 ,  514 . The second concrete slab  520  is formed to include the rebars  516 ,  518  (see step  408  in the process  400  of  FIG. 8 ). 
       FIG. 12  shows the floor construction  500   d , wherein the second concrete slab ( 520  shown in  FIG. 11 ) has been tensioned to become a second post-tensioned concrete slab  522 . Thus, the volume of the second post-tensioned concrete slab  522  has changed from the volume of the second concrete slab ( 520  shown in  FIG. 11 ), and a length of the second concrete slab along the length direction of the rebars  516 ,  518  has been reduced by the tensioning, indicated by ΔL 2 . Near or at the ends of the rebars  516 ,  518  at the location  510  where the gap now exists, the splice devices  512 ,  514  are not secured to the rebars  516 ,  518 . Thus, during the change in volume and length of the second concrete slab, the rebars  516 ,  518  are allowed to move with respect to the splice device  512 ,  514  (see step  410  in the process  400  of  FIG. 8 ). For example, as the length of the second concrete slab is reduced, thus lengthening the location  510  between the first post-tensioned concrete slab  504  and the second post-tensioned concrete slab  520 , the rebars  516 ,  518  may move (e.g., slide) away from the respective splice devices  512 ,  514  in the direction of the length change indicated by ΔL 3 . In the embodiments, ΔL 2  is equal to, the same as, or substantially similar to ΔL 3 . The length change ΔL 3  does not move the end portion of the rebars  516 ,  518  so much that the length change ΔL 3  prevents the rebars  516 ,  518  from being connected and/or fixedly secured to the respective splice devices  512 ,  514 . This prevention is predetermined in the positioning of the rebars  516 ,  518 , for example, in step  406  in the process  400  of  FIG. 8 , and/or structural features included in the splice devices  512 ,  514 . 
     After the volume change due to tensioning has been completed and the second post-tensioned concrete slab  522  has formed, the gap  524  between the first post-tensioned concrete slab  504  and the second post-tensioned concrete slab  522  is substantially defined. The gap  524  is preferably less than a foot in distance between the ends of the first post-tensioned concrete slab  504  and the second post-tensioned concrete slab  522 . However, it is required that the minimum distance of the gap  524  is the length of the splice device (e.g.,  512 ,  514  shown in  FIG. 13 ) that will be used in the gap  524 . 
       FIG. 13  shows the floor construction  500   e , wherein the splice devices  512 ,  514  have been positioned at the end portions of the respective rebars  506 ,  508 ,  516 ,  518 , and the splice devices  512 ,  514  have been securely connected to the end portions of the respective rebars  506 ,  508 ,  516 ,  518  (see step  412  in the process  400  of  FIG. 8 ). The connection (e.g., fixedly securing) can be made by mechanical means (e.g., frictional engagement). The connection can be completed by filling one or more internal chamber of each of the splice devices  512 ,  514  that contain the respective end portions of the rebars  506 ,  508 ,  516 ,  518  with grout material thus securely binding the end portions of the respective rebars  506 ,  508 ,  516 ,  518  to the splice devices  512 ,  514 . After the grout material fills in the internal chamber of each of the splice devices  512 ,  514 , the respective rebars  506 ,  508 ,  516 ,  518  are connected securely to the respective splice device  512 ,  514 . Each of the splice devices  512 ,  514  provides structural integrity to the floor construction  500   e . Thus, the splice devices  512 ,  514  become the force and/or tension transferring devices. That is, force and/or tension can be transferred through the splice devices  512 ,  514  to and/or from the respective rebars  506 ,  508 ,  516 ,  518  connected thereto. Preferably, the grout material is stronger than the concrete slab. An embodiment of the splice devices  512 ,  514  has a length of about twelve (12) inches. In other embodiments, the splice devices  512 ,  514  have lengths ranging from six (6) inches to twelve (12) inches. 
     The floor construction  500   e  is positioned substantially horizontal with respect to the earth, and the floor construction  500   e  includes the first post-tensioned concrete slab  504  and the second post-tensioned concrete slab  522  separated by the gap  524 . In the gap  524  space, the splice device  512  is connected and/or secured to both rebars  506 ,  516 . Also in the gap  524  space, the splice device  514  is connected and/or secured to both rebars  508 ,  518 . The splice devices  512 ,  514  are secured to the respective rebars  506 ,  508 ,  516 ,  518  with sufficient strength for structural applicability for connecting the two post-tensioned concrete slabs  504 ,  522  for structural purposes. 
       FIG. 14  shows the floor construction  500   f , wherein the gap  524  has been filled in with a material to form a pour strip  526  (see step  414  in the process  400  of  FIG. 8 ). The pour strip  526  covers the splice devices  512 ,  514 . It is preferable that the splice devices  512 ,  514  positioned in the gap  524  are completely covered by the pour strip  526 . 
       FIG. 15  shows a flow chart of an embodiment of a process  600  for constructing the floor construction with reduced gap design. The process includes a step  602  of forming a first concrete slab for post-tensioning, wherein the first concrete slab includes one or more rebars. Ends of the rebars are positioned to extend out from an edge of the first slab. It is preferable that these ends of the rebars do not extend more than six inches beyond the edge of the first slab. The process includes not positioning at this time a splice device at the end of the rebar. Accordingly, a splice device is not positioned at each of the ends of the rebars that are exposed in the gap. Then, in step  604 , the first concrete slab is tensioned forming a first post-tensioned concrete slab. 
     The process  600  includes a step  606  of pouring and forming the second concrete slab. The rebars for the second concrete slab are positioned so that their ends are positioned near respective ends of the respective rebars of the first post-tensioned concrete slab. For example, the ends of the rebars of the second concrete slab are positioned so that the rebars of the second concrete slab are generally in line with the respective rebars of the first post-tensioned concrete slab. It is preferable that the positioning of the rebars for the second concrete slab with respect to the splice devices are done after the first concrete slab has been tensioned (e.g., using the wire strand system that is included in the first concrete slab) and has gone through the volume change, becoming the first post-tensioned concrete slab. Thus, the positioning of the rebars for the second concrete slab can be done with a desired gap space distance in mind. That is, after the first post-tensioned concrete slab has formed, the length change along the length direction of the rebars would have been completed. It is preferable that the gap distance is less than a foot. Further, at this stage in the process  600 , the splice devices are not yet positioned where the gap between the first and second concrete slabs will exist when the second concrete slab is formed. 
     Then, in step  608 , the second concrete slab is allowed to shorten along the length direction of the rebar by and due to tensioning of a wire strand system in the second concrete slab. Because the rebars for the second concrete slab can and do move with respect to the respective ends of the rebars of the first post-tensioned concrete slab during the tensioning of the second concrete slab. 
     After the volume changes due to tensioning of the second concrete slab has been completed, the second concrete slab is the second post-tensioned concrete slab. The process  600  includes a step  610  of positioning a splice device at one end portion of the rebar of the first post-tensioned concrete slab and at one end portion of the rebar of the second post-tensioned concrete slab. Then, in step  612 , the splice device is connected to the end portions of the rebars. Preferably, the two rebus that are connected to the splice device are generally in line with each other. Carrying out the connection step  612  can depend on the particular features of the splice device used, as shown in examples in  FIGS. 20, 21, and 27 . For example, the splice device can be welded to one or more of the rebars. 
     At this stage in the process, the gap between the first post-tensioned concrete slab and the second post-tensioned concrete slab is generally fixed. Accordingly, the gap distance is generally known. The gap distance of three feet or less is possible. Preferably, the gap distance is one foot or less. 
     The process  600  includes a step  614  of filling in the gap between the first and second post-tensioned concrete slabs with material to form a pour strip. When the pour strip is formed in the gap, the splice devices connected to the rebars of the first and second post-tensioned concrete slabs are covered by the pour strip. It is preferable that the splice devices positioned in the gap are completely covered by the pour strip. 
       FIGS. 16-20 and 22  show schematic side views of floor constructions  700   a - f , respectfully, being constructed according to the process  600  described above and shown in  FIG. 15 . Like elements are referred to with the same reference numerals. 
       FIG. 16  shows the floor construction  700   a , wherein a first concrete slab  702  is formed with rebars  704 ,  706  therein (see step  602  in the process  600  of  FIG. 15 ). End portions of the rebars  704 ,  706  are positioned to extend beyond the first concrete slab  702  at a location  708  where a gap will exist when a second concrete slab is formed. 
       FIG. 17  shows the floor construction  700   b , wherein the first concrete slab ( 702  shown in  FIG. 16 ) has been tensioned and has become a first post-tensioned concrete slab  710  (see step  604  in the process  600  of  FIG. 15 ). The volume of the first post-tensioned concrete slab  710  has changed from the volume of the first concrete slab ( 702  shown in  FIG. 16 ), and a length of the first concrete slab along the length direction of the rebars  704 ,  706  has been reduced by the tensioning, indicated by ΔL 4 . Near or at the ends of the rebars  704 ,  706  at the location  708  where the gap will exist when a second concrete slab is formed, a splice device is not yet positioned at the ends of the rebars  704 ,  706 . 
       FIG. 18  shows the floor construction  700   c , wherein additional rebars  711 ,  712  of the second concrete slab  714  are positioned so that the respective ends of the rebars  711 ,  712  are in the location  708 , and also positioned near ends of the respective rebars  704 ,  706  of the first post-tensioned concrete slab  710 . The rebars  711 ,  712  are generally in line with length directions of the rebars  704 ,  706 . The second concrete slab  520  is poured and formed (see step  606  in the process  600  of  FIG. 15 ). 
       FIG. 19  shows the floor construction  700   d , wherein the second concrete slab ( 714  shown in  FIG. 18 ) has been tensioned and has become a second post-tensioned concrete slab  716 . Thus, the volume of the second post-tensioned concrete slab  716  has changed from the volume of the second concrete slab ( 714  shown in  FIG. 18 ), and a length of the second concrete slab along the length direction of the rebars  711 ,  712  has been reduced by the tensioning, indicated by ΔL 6 . Near the ends of the rebars  711 ,  712  a gap  718  between the first and second post-tensioned concrete slabs  710 ,  716  now exists. There are no splice devices positioned at the rebars  704 ,  706 ,  711 ,  712 , yet. 
     During the change in volume and length of the second concrete slab, the rebars  711 ,  712  are allowed to move with respect to the rebars  704 ,  706  (see step  608  in the process  600  of  FIG. 15 ). As the length of the second concrete slab is reduced, the location  708  between the slabs lengthens forming the gap  718 . The rebars  711 ,  712  may move (e.g., slide) away from the respective rebars  704 ,  706  in the direction of the length change indicated by ΔL 6 . The shortening distance ΔL 5  can be equal to, substantially be the same as, or substantially similar to ΔL 6 . The shortening distance ΔL 5  can be different from ΔL 6 . 
     After the volume change due to tensioning has been completed and the second post-tensioned concrete slab  716  has formed, the gap  718  between the first post-tensioned concrete slab  710  and the second post-tensioned concrete slab  716  is substantially defined. The gap  718  is preferably less than a foot in distance. However, the minimum distance of the gap  718  must be the length of the splice device (e.g.,  720 ,  722  shown in  FIG. 20 ) that will be used in the gap  718 . For example, the splice device (e.g.,  720 ,  722  shown in  FIG. 20 ) can have a length of from six (6) inches to twelve (12) inches. 
       FIG. 20  shows the floor construction  700   e , wherein the splice devices  720 ,  722  have been positioned at the end portions of the respective rebars  704 ,  706 ,  711 ,  712  (see step  610  of the process  600  in  FIG. 15 ). 
     The splice devices  720 ,  722  are then securely connected to the rebars  704 ,  706 ,  711 ,  712  (see step  612  of the process  600  in  FIG. 15 ). For example, the splice devices  720 ,  722  can be welded to the rebars  704 ,  706 ,  711 ,  712 . 
       FIG. 21  shows a cross-sectional view in the gap portion of the floor construction  700   e  shown in  FIG. 20 . The splice devices  720 ,  722  include a substantially “V-shaped” cross section for providing at least one, preferably two, surfaces for welding each of the respective rebars  704 ,  706 ,  711 ,  712 . 
     The floor construction  700   e  is positioned substantially horizontal with respect to the earth. In the gap  718 , the splice devices  720 ,  722  are secured to the respective rebars  704 ,  706 ,  711 ,  712  with sufficient strength for structural applicability for connecting the two post-tensioned concrete slabs  710 ,  716  for structural purposes. 
       FIG. 22  shows the floor construction  700   f , wherein the gap  718  has been filled in with a material to form a pour strip  724  (see step  614  in the process  400  of  FIG. 15 ). The pour strip  724  covers the splice devices  720 ,  722 . It is preferable that the splice devices  720 ,  722  positioned in the gap  718  are completely covered by the pour strip  724 . 
     Applications of the embodiments disclosed herein include all aspects of construction, including, but not limited to, buildings, towers, floating terminals, ocean structures and ships, storage tanks, nuclear containing vessels, bridge piers, bridge ducts, foundation soil anchorages, and virtually all other types of installations where normally reinforced concrete may be acceptable. 
     Preferred embodiments have been described. Those skilled in the art will appreciate that various modifications and substitutions are possible, without departing from the scope of the invention as claimed and disclosed, including the full scope of equivalents thereof.