POST-TENSION CONCRETE LEAVE OUT SPLICING SYSTEM AND METHOD
This description relates generally to floor construction using post-tensioned concrete slabs. 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 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). 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 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. Referring back to Devices, systems, and methods for connecting post-tensioned concrete slabs in new floor construction that 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 can 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 the concrete construction (e.g., a new floor construction) includes a first post-tensioned concrete slab and a second post-tensioned concrete slab, the first post-tensioned concrete slab and the second post-tensioned concrete slab having respective upper surfaces that are generally aligned, the first post-tensioned concrete slab including a first rebar installed therein, the second post-tensioned concrete slab including a second rebar installed therein, the first post-tensioned concrete slab and the second post-tensioned concrete slab being separated by a gap so that the concrete material of the first post-tensioned concrete slab is not in contact with the concrete material of the second post-tensioned concrete slab. The floor construction comprises a splice device positioned in the gap splicing together an end portion of the first rebar and an end portion of the second rebar, the splice device includes a first cavity that contains the end portion of the first rebar, and a second cavity that contains the end portion of the second rebar, and a body having a hole, wherein the hole receives a bolt which penetrates through the hole from an outside of the body into the first cavity and engages a portion of the first rebar inside the first cavity. In an embodiment of the concrete construction, the body of the splice device includes another hole that receives another bolt which penetrates through that hole from the outside of the body into the second cavity and engages a portion of the second rebar inside the second cavity. 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 In another embodiment of the concrete construction, the splice device splices together the first rebar and the second rebar so that the first rebar and the second rebar are generally parallel with each other. In another embodiment of the concrete construction, the splice device splices together the first rebar and the second rebar so that the first rebar and the second rebar are generally inline. Another embodiment of the concrete construction comprises a strip of non-shrink material being in the gap, wherein the strip has a compressive strength that is greater than or equal to the compressive strength of the concrete material of the first post-tensioned concrete slab and/or the concrete material of the first post-tensioned concrete slab. In another embodiment of the concrete construction, the strip of non-shrink material completely surrounds the splice device. In another 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 An embodiment of a method for making a concrete construction comprises forming a first post-tensioned concrete slab, wherein the first post-tensioned concrete slab includes a first rebar installed therein, either prior to or after a second post-tensioned concrete slab has been created, securely connecting a splice device to an end portion of the first rebar, before the second post-tensioned concrete slab has been created, positioning an end portion of a second rebar inside the splice device but not securely connected thereto, creating a second post-tensioned concrete slab so that the second rebar is installed therein, wherein the first post-tensioned concrete slab and the second post-tensioned concrete slab are separated by a gap so that the concrete material of the first post-tensioned concrete slab is not in contact with the concrete material of the second post-tensioned concrete slab, and the end portion of the second rebar is allowed to move with respect to the splice device during the creating of the second post-tensioned concrete slab, and securely connecting the splice device to the end portion of the second rebar. In another embodiment of the method, 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 Another embodiment of the method comprises forming a strip of material in the gap with a non-shrink material, wherein the strip has a compressive strength that is greater than or equal to the compressive strength of the concrete material of the first post-tensioned concrete slab and/or the concrete material of the first post-tensioned concrete slab. 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 project time delay caused by the existence of conventional gaps in the floor construction can be reduced and/or eliminated. 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 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. 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 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 (e.g., fixed) to the splice devices, the rebars can and do move with respect to the splice devices during the tensioning of the second concrete slab in step 410. After the volume changes due to tensioning of the second concrete slab has completed, the second concrete slab has become the second post-tensioned concrete slab. The process 400 includes a step 412 of fixing (e.g., 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 fixed to the splice device. 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 and fixed at this stage in the process. Preferably, the gap distance at this stage is less than a foot. The process 400 includes a step 414 of filling in the gap between the first and second post-tensioned concrete slabs with a material to form a pour strip. When the pour strip is formed in the gap, the splice devices fixed with respect 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. 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. An embodiment of the splice device (e.g., 206 of Further, the splice device 600 includes a mechanical component for securing and/or connecting the body 602 to the second rebar 208. An embodiment of the mechanical component is one or more bolts 616. The body 602 has one or more holes 618, wherein each hole 618 is configured to receive the bolt 616 and allow the bolt 616 to penetrate into the second cavity 606. The bolt 616 engages and penetrates through the hole 618. An end of the bolt 616 engages a portion of the second rebar 208 contained in the second cavity 606. The engagement of the bolt 616 to the hole 618, and the engagement of the end of the bolt 616 to the second rebar 208 inside the second cavity 606, secures and/or connects the splice device 600 to the second rebar 208. The bolt 616 can be configured to be tightened through the hole 618 to engage the second rebar 208 with sufficient force to immobilize the second rebar 208 with respect to the splice device 600. An embodiment of the bolt 616 is a threaded bolt 616. An embodiment of the hole 618 is a threaded hole 618, wherein the threaded hole 618 has threads that match (i.e., mate to) the threads of the threaded bolt 616. An embodiment of the bolt 616 has a snap-off head 620, so that when a torque applied to the head for screwing the bolt 616 meets or exceeds a predetermined amount of torque, the head 620 is configured to snap off from the rest of the bolt 616. Accordingly, the securing and/or connecting the bolt 616 to the second rebar 208 will have a known (and predetermined) force according to the configuration and design of the snap-off head 620. 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 fill scope of equivalents thereof. Devices, systems, and methods for constructing post-tensioned concrete slabs in a new floor construction that has a reduced gap distance between the slabs. The devices, systems, and methods can improve project construction time by reducing the time delay in accessing the floor underneath the slabs due to safety and/or weather conditions. 1. A concrete construction including 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 concrete construction comprising:
a splice device positioned in the gap for connecting to an end portion of the first rebar and to an end portion of the second rebar, said splice device includes a first cavity that contains said end portion of the first rebar, and a second cavity that contains said end portion of the second rebar, and a body having a hole, wherein said hole receives a bolt which penetrates through said hole from an outside of said body into said first cavity and engages a portion of the first rebar inside said first cavity. 2. The concrete construction according to 3. The concrete construction according to 4. The concrete construction according to 5. The concrete construction according to 6. The concrete construction according to a strip of non-shrink material being 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. 7. The concrete construction according to 8. A concrete construction including 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 concrete construction comprising:
a splice device positioned in the gap connecting an end portion of the first rebar and an end portion of the second rebar; and a strip of non-shrink material being in the gap and completely surrounding said splice device, wherein said strip has a compressive strength that is greater than or equal to the compressive strength of the concrete material of said first and second post-tensioned concrete slabs, wherein said splice device includes a body defining a first cavity and a second cavity, said first cavity being separated from said second cavity, said first cavity contains said end portion of the first rebar, and said second cavity contains said end portion of the second rebar, said splice device further includes a first hole that receives a first bolt which penetrates through said first hole from an outside of said body into said first cavity and engages a portion of the first rebar inside said first cavity, and a second hole that receives a second bolt which penetrates through said second hole from said outside of said body into said second cavity and engages a portion of the second rebar inside said second cavity. 9. The concrete construction according to 10. A method for making a concrete construction including a first post-tensioned concrete slab and a second post-tensioned concrete slab, comprising:
forming said first post-tensioned concrete slab, wherein said first post-tensioned concrete slab includes a first rebar installed therein; either prior to or after a second post-tensioned concrete slab has been created, securely connecting a splice device to an end portion of the first rebar; before the second post-tensioned concrete slab has been created, positioning an end portion of a second rebar inside the splice device but not securely connected thereto; creating 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 second rebar. 11. The method according to 12. The method according to 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.FIELD
BACKGROUND
BRIEF SUMMARY
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION









