Patent Publication Number: US-10787813-B2

Title: Tendon coupler

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. provisional application No. 62/660,078, filed Apr. 19, 2018. 
    
    
     FIELD 
     The present application relates to a coupler for joining tendons in concrete. 
     BACKGROUND 
     Concrete is capable of withstanding significant compressive loads but is more susceptible to failure when subjected to significant tensile loads. Concrete structures are often reinforced with steel bars or cables to enhance the structures ability to withstand tensile forces. 
     SUMMARY 
     In an aspect, a coupler for connecting an end of a first tendon to an end of a second tendon may include a body, at least one first wedge for receiving the end of the first tendon, and at least one second wedge for receiving the end of the second tendon. The body may have a first end and a second end and the at least one first wedge and the at least one second wedge may be positioned in the first and second ends of the body, respectively. The coupler may further include a first piston positioned proximate the first wedge and configured to apply a force on the first wedge toward the first end. The coupler may further include a second piston positioned proximate the second wedge and configured to apply a force on the second wedge toward the second end. 
     In some aspects, a coupler may include a first chuck that receives a first wedge and a second chuck that receives a second wedge. The first chuck may include an outer surface and first external threads. The second chuck may include an outer surface and second external threads. A first end of a coupler body may include first internal threads that engage the first external threads and a second end of a coupler body may include second internal threads that engage the second external threads. 
     In some aspects, a coupler may include a body with a passageway that may be in communication with an end surface of a first piston and with an end surface of a second piston. The passageway may be configured to receive a fluid, and the fluid may be configured to move the first piston and the second piston. 
     In some aspects, a coupler may include a body having a passageway therethrough and an aperture or access port that may be in fluid communication with the passageway. The aperture may be tapered proximate the passageway. The taper may increase the flowrate of a fluid received into the passageway. 
     In some aspects, a coupler may include a first piston and a second piston, which each include a recess. An end of a first tendon may be configured to be positioned in the recess of the first piston and an end of a second tendon may be configured to be positioned in the recess of the second piston. 
     In some aspects, a coupler may include a first chuck that has a first tapered chamber and a second chuck that has a second tapered chamber. A first wedge may be positioned in the first tapered chamber and a second wedge positioned in the second tapered chamber. 
     In some aspects, a coupler may include a first wedge and a second wedge that are initially disposed in a first position. The application of a force by a first piston on the first wedge inserts the wedge into a second, secured position and the application of a force by a second piston on the second wedge inserts the second wedge into a second, secured position. 
     In some aspects, a coupler may include a first piston and a second piston that are driven by a pressurized fluid positioned in the body. The pressurized fluid applies a pressure on the first piston and on the second piston. 
     In some aspects, a coupler may include a first piston and a second piston that are driven by a chemical reaction that increases pressure in a coupler body. The chemical reaction applies a pressure against the first piston and the second piston. 
     In some aspects, a coupler may include a chuck coupled to a first end of a coupler body. The chuck receives first wedges, which include an upper wedge and a lower wedge that together define a cavity. The upper wedge and the lower wedge are moveable out of the first chuck and into a passageway of the coupler body. 
     In another aspect, a coupler for connecting an end of a first tendon to an end of a second tendon may include a body, a first piston, and a second piston. The body may include a first end, a second end, and a passageway providing communication between the first end and the second end. The first piston may be positioned proximate the first end and driven to exert a first force toward the first end. The second piston may be positioned proximate the second end and driven to exert a second force toward the second end. 
     In some aspects, a coupler may include a first piston driven to exert a first force, and a second piston driven to exert a second force. The first force and the second force may be equal to one another. 
     In some aspects, a coupler may include a body with an aperture that may be oriented orthogonal to a passageway of the body. The passageway may be configured to receive a fluid through the aperture. The fluid may be configured to provide a first force to a first piston positioned in the body, and a second force to a second piston positioned in the body. 
     In some aspects, a coupler may include a first chuck with first wedges that receive an end of a first tendon. The coupler also may include a second chuck with second wedges that receive an end of a second tendon. A first end of a coupler body receives the first chuck and a second end of the coupler body receives the second chuck. 
     In some aspects, a coupler may include a first piston and a second piston. The first piston may apply a force on first wedges directed toward a first end of the coupler and the second piston may apply a force on second wedges directed toward a second end of the coupler. 
     In another aspect, a method for connecting an end of a first tendon to an end of a second tendon may include positioning a coupler between the end of the first tendon and the end of the second tendon, wherein the coupler may include a body with a first end and a second end and a passageway and first and second pistons positioned in the passageway proximate the first and second ends, respectively. A first chuck may be inserted into the first end of the body and a second chuck may be inserted into the second end of the body. The end of the first tendon may be inserted into first wedges of the first chuck, the first wedges supported by the first chuck, and the end of the second tendon may be inserted into second wedges of the second chuck, the second wedges supported by the second chuck. The first piston and second pistons may each apply a force to the first wedges and second wedges, respectively. 
     In some aspects, a method for connecting an end of a first tendon to an end of a second tendon may include pumping fluid into the passageway through an aperture oriented perpendicular to the passageway, a first pressure actuating the first piston and a second pressure actuating the second piston. 
     In some aspects, a method for connecting an end of a first tendon to an end of a second tendon may include removing at least a portion of the fluid from the passageway after actuating the first piston and the second piston. 
     In some aspects, a method for connecting an end of a first tendon to an end of a second tendon may include moving the first and second wedges from a first position wherein the first wedges and the second wedges are unsecured with respect to one another to a second position wherein the wedges are secured with respect to one another. 
     In some aspects, a method for connecting an end of a first tendon to an end of a second tendon may include applying an equal force to the first piston and the second piston. 
     Independent features and independent advantages will become apparent to those skilled in the art upon review of the detailed description, drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of a reinforced concrete structure including a tendon. 
         FIG. 2  is a perspective view of a coupler. 
         FIG. 3  is a section view of the coupler of  FIG. 2 , viewed along section  3 - 3 . 
         FIG. 4  is an exploded view of the coupler of  FIG. 2 . 
         FIG. 5  is an enlarged view of a portion of  FIG. 3   
         FIG. 6  is an enlarged view of the coupler body of  FIG. 5 , illustrating area  6 . 
         FIG. 7  is an end view of a piston. 
         FIG. 8  is a section view of the piston of  FIG. 7 , viewed along section  8 - 8 . 
         FIG. 9  is a perspective view of a plug. 
         FIG. 10  is a section view of a coupler according to another embodiment. 
         FIG. 11  is an enlarged view of embodiment portion of the coupler of  FIG. 10 . 
         FIG. 12  is a section view of a piston according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The concepts disclosed herein are capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
       FIG. 1  illustrates reinforced concrete structure  14  in which first and second tendons  18   a ,  18   b  extend through concrete structure  14  and are coupled by coupler  200 . First anchor  22  may be positioned at first end  24  of concrete structure  14 . One end of first tendon  18   a  may be secured to first anchor  22  while the opposite end of first tendon  18   a  may be secured to one end of coupler  200 . A first end of second tendon  18   b  may be secured to an opposite end of coupler  200  and a second end of second tendon  18   b  may extend through the concrete to another end  38  of the concrete structure, which may include a partition or an end wall (i.e., an end of the concrete structure). The second end of second tendon  18   b  may be secured to a second anchor  42  positioned adjacent the end  38 . Although one tendon and coupler assembly is shown in  FIG. 1 , the concrete structure may include multiple tendons and/or couplers, which may be oriented parallel to and/or may overlap one another. 
       FIGS. 2-4  illustrate coupler  200  including coupler body  202 . In the illustrated embodiment, coupler body  202  may be cylindrical and may have first end  204  with first opening  206  and second end  208  with second opening  210 . In the illustrated embodiment, body axis  216  extends between first end  204  and second end  208  and passageway  212  ( FIG. 4 ) extends parallel to body axis  216  through coupler body  202  between first opening  206  and second opening  210 . 
     As shown in  FIG. 5 , coupler body  202  may include inner surface  220  and outer surface  224 . In the illustrated embodiment, inner surface  220  may be stepped and may include separate sections having different diameters. A first section of inner surface  220  having a diameter D 1  defines pressure chamber  228 . In some embodiments, pressure chamber  228  may be located at a central point in coupler body  202 . On each side of and adjacent to pressure chamber  228 , inner surface  220  may define piston chamber  232  having diameter D 2 , where D 2  is larger than D 1 . The portion of passageway  212  between each piston chamber  232  and respective ends  204 ,  208  of coupler body  202  defines chuck receiving section  236 . Chuck receiving sections  236  may have third diameter D 3  that may be larger than D 2 . Chuck receiving sections  236  may also include threads  240 . In the illustrated embodiment, threads  240  extend along a length of each chuck receiving section  236 . 
     In the illustrated embodiment, coupler body  202  also may include access port  239  that extends through the wall of coupler body  202  and provides communication between outer surface  224  and pressure chamber  228 . Access port  239  may be perpendicular to body axis  216 . As shown in  FIG. 6 , access port  239  may include a counterbore, including a first portion  243  proximate outer surface  224  and has diameter D 5 , and second portion  245  that has diameter D 4  and extends between first portion  243  and pressure chamber  228 . Access port  239  may include shoulder  242  and tapered section  244  between first portion  243  and second portion  245 . In the illustrated embodiment, D 4  may be less than D 5 . In some embodiments (e.g.,  FIG. 11 ), access port  239  may have a single diameter and may not include a tapered section. 
     As shown in  FIGS. 3 and 4 , piston  248  may be slidably positioned within each of piston chambers  232  of coupler body  202  and chuck  264  may be positioned outwardly of each piston  248 . Each piston  248  may have a generally cylindrical profile with a diameter approximately equivalent to D 2 . Piston  248  may be sized and configured to slide into opening  206  and through chuck receiving section  236  and piston chamber  232 . 
     As drawn in  FIG. 3 , the left-hand piston  248  is shown in an un-seated position and the right-hand piston  248  is shown in a seated position. It will be understood that this depiction is for purposes of illustration only. In most embodiments, both pistons  248  will move substantially in tandem and thus will, for example, both occupy an unseated position before seating and both occupy a seated position after seating. 
     Chuck  264  may be coupled to coupler body  202  proximate each of first end and second ends  204 ,  208 . Each chuck  264  may have threaded outer surface  268  adapted to mate with threads  240 . In the illustrated embodiment, each chuck  264  has an end portion wider than threaded outer surface  268 . The end portion may act as a stop surface to prevent chuck  264  from being inserted beyond a predetermined point and can prevent chuck  264  from being flush with end of the body  202 . Each chuck  264  may include a tapered bore  270  having internal surface  272 . A center of passageway  212  may be aligned with body axis  216 . In the illustrated embodiment, internal surface  272  may be tapered and may have its largest diameter proximate piston chamber  232 . Chucks  264  may be positioned so that the portions of tapered bores  270  having a largest diameter face one another. 
     In some embodiments, frustoconical wedge  276  may be positioned within each tapered bore  270 . In some embodiments, wedges  276  may include at least first wedge section  276   a  and second wedge section  276   b . Each wedge section  276   a ,  276   b  may include an frustoconical outer surface  280  and a bore surface  284  ( FIG. 4 ). Outer surfaces  280  may be configured to seat in tapered bore  270 . In the illustrated embodiment, bore surfaces  284  include grooves  286 . When wedge sections  276   a ,  276   b  fit together, bore surfaces  284  are adjacent and define a tendon-receiving passageway  288 . Each recessed surface  284  may have a generally semi-circular profile, so that passageway  288  is generally circular. Passageway  288  may be concentric with body axis  216 . 
     As shown in  FIGS. 7 and 8 , each piston  248  may have front surface  252  and rear surface  260 . In the illustrated embodiment, front surface  252  may include recess  256  that may be concentric with an outer perimeter of piston  248 . Recess  256  may be generally circular and may include a taper that extends toward rear surface  260 . Opening of recess  256  at front surface  252  may have a larger diameter than the back surface of recess  256 . Rear surface  260  of piston  248  may be substantially flat. Groove  296  ( FIG. 8 ) may extend around an outer perimeter of piston  248  and may receive seal  292  ( FIG. 4 ) for sealingly engaging inner surface  220 . While inserted into coupler body  202 , rear surface  260  of each piston  248  may be positioned proximate a stepped surface between piston chamber  232  and pressure chamber  228 . 
     In some embodiments, as shown in  FIG. 12 , the body of each piston  248  may extend to form shoulder portion  290  and rear surface  260  may be spaced farther from front surface  252  than piston  248  shown in  FIG. 8 . Shoulder portion  290  may also extend into pressure chamber  228  while piston  248  is positioned within coupler body  202  ( FIG. 10 ), thereby reducing the volume of air present in pressure chamber  228 . 
     In operation, an end of first tendon  18   a  ( FIG. 1 ) may be coupled to chuck  264  proximate first end  204  of coupler body  202  and an end of second tendon  18   b  ( FIG. 1 ) may be coupled to another chuck  264  proximate second end  208  of coupler body  202 . Each of the tendons  18   a ,  18   b  may be received within passageway  288  of wedge sections  276   a ,  276   b  as the tendon moves into the respective chucks  264 . Tendons  18   a ,  18   b  and wedges  276  move toward each other as tendons  18   a ,  18   b  are inserted toward respective pistons  248  and tendons  18   a ,  18   b  may force the respective wedge sections  276   a ,  276   b  apart so that passageway  288  becomes wider. If desired, the end of each tendon  18   a ,  18   b  may be positioned within or adjacent to the recess  256  of respective pistons  248 . If present, a wave spring may resist dislodgement of wedge  276  from each chuck  264 . 
     After tendons  18   a ,  18   b  are positioned within cavity  288 , a force may be applied within coupler body  202  urge wedge sections  276   a ,  276   b  into each chuck  264  and thereby seat wedges  276 . In the embodiment illustrated in  FIG. 3 , nozzle  278  connected to a fluid source may be coupled to access port  239  to inject a pressurized fluid (e.g., oil, grease) from a pump (not shown) into passageway  212 . If desired, nozzle  278  may include a stepped surface abutting shoulder  242  and nozzle  278  may direct fluid through tapered section  244  ( FIG. 6 ). If desired, such as, for example, if nozzle  278  is a high pressure nozzle, access port  239  may include threads for engaging nozzle  278 . 
     Fluid from nozzle  278  enters pressure chamber  228  and flows toward piston chambers  232 . The fluid contacts surfaces  260  of pistons  248  and applies an outward hydraulic force. The fluid applies a force directed toward the ends  204 ,  208  of coupler body  202 . The hydraulic force applied to each piston may be equal. In some embodiments, seal  292  may be positioned in groove  296  of each piston  248  so as to limit fluid flowing around each pistons  248 . The hydraulic force urges each piston  248  outwardly, away from the other piston and toward a respective end of coupler body  202 . As each piston  248  moves, each piston  248  contacts wedge sections  276   a ,  276   b  in respective chuck  264  and advances wedge sections  276   a ,  276   b  into tapered bore  270  (see rightmost piston  248  in  FIG. 3 ). In some embodiments, a biasing element (e.g., a wave spring or wave washer—not shown) may be positioned within the body to provide a nominal biasing force on wedges  276  to initially seat wedge  276  within tapered bore  270 . As a result, as pistons  248  are urged outwardly, each piston  248  first engages an end of the associated tendon and then contacts the associated wedge  276 . Pistons  248  can seat wedges  276  with a minimal applied load. 
     In other embodiments, another mechanism may be used for actuating pistons  248 . Instead of introducing pressurized fluid, which may be, for example, a hydraulic fluid or pneumatic fluid, into coupler body  202 , a mechanical device may be used to apply a force or torque on pistons  248  to move them against wedges  276 . In some embodiments, a chemical may be introduced into the space between pistons  248  and a catalyst may be introduced to cause a chemical reaction that increases the pressure in the space between pistons  248  and drives each piston  248  against its respective wedge  276 . The chemical reaction may include, among other things, igniting or combusting a fuel. 
     As wedge sections  276   a ,  276   b  move into tapered bore  270 , the taper of internal surface  272  forces wedge sections  276   a ,  276   b  together. The diameter of passageway  288  may be reduced. Reducing the diameter of passageway  288  secures tendons  18   a ,  18   b  to coupler  200 . Additionally, grooves  286  on bore surfaces  284  may grip tendons  18   a ,  18   b  as wedge sections  276   a ,  276   b  are seated. Once wedge sections  276   a ,  276   b  are fully seated within tapered bore  270  (i.e., piston  248  can no longer move wedge sections  276   a ,  276   b  farther into chuck  264 ), tendons  18   a ,  18   b  are secured within coupler. Nozzle  278  may be removed from aperture  239 . In some embodiments, at least some of the fluid in passageway  212  may be retained to provide corrosion protection. In other embodiments, the fluid may be drained from passageway  212  via aperture  239 . Plug  300  ( FIG. 9 ) may be used to seal the access port  239  after nozzle  278  has been removed to further seal passageway  212 . In some embodiments, plug  300  may include a cap body  308  and a flange portion  304 . Cap body  308  may be inserted into access port  239  until flange portion  304  contacts a flat portion  241  of outer surface  224 . In some embodiments (e.g.,  FIGS. 10 and 11 ), access port  239  may be threaded so as to engage a threaded nozzle  278 . Cap body  308  may also be threaded. 
     Providing an internal force may require less total force to seat the wedge sections  276   a ,  276   b  than may be required using an external force (e.g., tensioning tendons  18   a ,  18   b  with a jack). Additionally, applying an internal force limits any need to remove a portion of the tendon sheath (not shown) from tendons  18   a ,  18   b . Furthermore, if coupler  200  is used to repair/splice two tendons  18   a ,  18   b  after the surrounding concrete has set, only a section of concrete slightly larger than coupler  200  needs to be cut in order to seat wedge sections  276   a ,  276   b.    
     In some embodiments, after pistons  248  have fully seated wedges  276 , tendons  18   a ,  18   b  must be re-tensioned. By way of example, tendon  18   a  may be tensioned, (e.g., by a hydraulic tensioner—not shown, applied at first anchor  22 ). As the tension may be applied, wedge sections  276   a ,  276   b  may move farther into tapered bore  270  as wedge sections  276   a ,  276   b  move with tendon  18   a . An excess portion of the tendon tail (i.e., the portion extending beyond a minimum protruding from the first chuck  264 ) may be removed. Similar steps may be applied to tension the second tendon  18   b.    
     Although aspects have been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects as described. Likewise, unless an order of steps is explicitly stated, the sequential recitation of steps in the claims that follow is for clarity only and is not a requirement that the steps performed in the sequence recited.