Anchor for concrete post-tension anchoring

Abstract

An anchor for a concrete post-tension system. The anchor comprises a bearing plate portion, a barrel portion and a plurality of webs. The barrel portion has an upper annular wall extending from the upper surface of the bearing plate and a lower annular wall depending from the lower surface of the bearing plate. The inner surfaces of the upper annular wall and lower annular wall together define an internal wedge-receiving cavity passing through the bearing plate and having a central axis substantially perpendicular to the bearing plane. The wedge-receiving cavity has a fixed angle of taper with respect to the central axis. The cavity has a diameter at the lower end that is at least as great as the diameter of the sheathing on the tendon to be anchored. The cavity has an overall height that is at least as great as the height of the wedges to be used. The outer surface of the upper annular wall is upwardly tapered. The outer surface of the lower annular wall is downwardly tapered. A plurality of webs extend from the outside of the upper annular wall to the upper surface of the bearing plate. The sheathed portion of the tendon may freely pass through the wedge-receiving cavity of the anchor.

1 . An anchor for a concrete post-tension system including the anchor, a tendon having a longitudinal axis and a first diameter with at least one portion of the tendon being exposed and at least another portion of the tendon being encased in sheathing having a second diameter, and a plurality of wedges, each wedge having a height, a substantially semi-circular inner surface adapted to engage the exposed portion of the tendon and an outer surface with constant outer angle of taper with respect to the longitudinal axis, the anchor comprising: 
 a generally rectangular bearing plate portion having a upper surface and a generally flat lower surface defining a bearing plane;    a barrel portion having an upper annular wall extending from the upper surface of the bearing plate and a lower annular wall depending from the lower surface of the bearing plate, the inner surfaces of the upper annular wall and lower annular wall together defining an internal wedge-receiving cavity passing through the bearing plate and having a central axis substantially perpendicular to the bearing plane; 
 the wedge-receiving cavity having a fixed angle of taper with respect to the central axis such that the diameter of the cavity is constantly diminishing from the upper end of the barrel to the lower end of the barrel, the cavity having a diameter at the lower end that is at least as great as the diameter of the sheathing on the tendon to be anchored, and the cavity having an overall height measured from the upper end of the barrel to the lower end of the barrel that is at least as great as the height of the wedges to be used;  
 the outer surface of the upper annular wall being upwardly tapered such that the outside diameter of the wall decreases from the upper surface of the bearing plate to the upper end of the barrel;  
 the outer surface of the lower annular wall being downwardly tapered such that the outside diameter of the wall decreases from the lower surface of the bearing plate to the lower end of the barrel; and  
   a plurality of webs extending from the outside of the upper annular wall to the upper surface of the bearing plate;    whereby the sheathed portion of the tendon may freely pass through the wedge-receiving cavity of the anchor, and when an exposed portion of the tendon is positioned within the cavity, the wedges may be inserted to produce an interference fit relationship between the inner surfaces of the cavity and the exterior surface of the tendon.    
   
   
       2 . A post-tension anchor in accordance with  claim 1 , wherein the anchor is a one-piece metal casting.  
   
   
       3 . A post-tension anchor in accordance with  claim 1 , wherein the anchor is a metal casting encapsulated in a polymer material.  
   
   
       4 . A post-tension anchor in accordance with  claim 1 , wherein the upper surface of the bearing plate is disposed near the midpoint of the barrel, the distance from the upper end of the barrel to the upper surface of the bearing plate being within the range from about 46% to about 54% of the distance from the upper end of the barrel to the lower end of the barrel.  
   
   
       5 . A post-tension anchor in accordance with  claim 4 , wherein when the tendon to be anchored is encased in sheathing having a diameter within the range from about 0.62″ to about 0.67″, then the wedge-receiving cavity has an angle of taper that is within the range from about 0.67″ to about 0.75″.  
   
   
       6 . A post-tension anchor in accordance with  claim 5 , wherein when the wedges to be used have a height of about 1.25″ and an outside taper of about 7°, then the wedge-receiving cavity has a height from the upper end of the barrel to the lower end of the barrel that is within the range from about 1.25″ to about 1.30″, and the wedge-receiving cavity has an angle of taper that is within the range from about 6.5° to about 7.5°.  
   
   
       7 . A multi-purpose anchor for a post-tension anchoring system comprising an anchor body having an internal wedge-receiving cavity defined by a wall, said cavity has a constantly diminishing diameter extending from a first end of said anchor body to a second end of said anchor body, said cavity having an angel of taper with respect a centerline of said cavity, said cavity having a diameter at said second end.  
   
   
       8 . An anchor in accordance with  claim 7 , wherein said anchor body is a cast member.  
   
   
       9 . An anchor in accordance with  claim 7 , wherein said angle of taper is approximately 7° relative to the center line of said cavity.  
   
   
       10 . An anchor in accordance with  claim 7 , further comprising: 
 a tendon extending through said cavity; and    at least two wedges in interference fit relationship between said wall and an exterior surface of said tendon.    
   
   
       11 . An anchor in accordance with  10 , wherein each of said wedges has a length not greater than a length of said cavity.  
   
   
       12 . An anchor in accordance with  10 , wherein said tendon has a sheathing extending therearound, said diameter of said cavity at said second end being greater than a diameter of said sheathing on said tendon.  
   
   
       13 . An anchor in accordance with  claim 10 , wherein each of said wedges has a length approximately the same as the length of said cavity.  
   
   
       14 . An anchor in accordance with  claim 13 , wherein the length of said cavity is approximately 0.05″ greater than the length of each of said wedges.  
   
   
       15 . An anchor in accordance with  claim 14 , wherein said cavity has a length of 1.30″.  
   
   
       16 . An anchor in accordance with  claim 14 , wherein each of said wedges is in interference fit relationship with said cavity wall along the entire length of said cavity.  
   
   
       17 . An intermediate anchor for a post-tension system, comprising: 
 an anchor having a bearing plate portion and a barrel portion; 
 the bearing plate portion having a upper surface and a generally flat lower surface defining a bearing plane;  
 the a barrel portion having an upper annular wall extending from the upper surface of the bearing plate and a lower annular wall depending from the lower surface of the bearing plate, the inner surfaces of the upper annular wall and lower annular wall together defining an internal wedge-receiving cavity passing through the bearing plate and having a central axis substantially perpendicular to the bearing plane; 
 the wedge-receiving cavity having a fixed angle of taper with respect to the central axis such that the diameter of the cavity is constantly diminishing from the upper end of the barrel to the lower end of the barrel,  
 the outer surface of the upper annular wall being upwardly tapered such that the outside diameter of the wall increases from the upper end of the barrel to the upper surface of the bearing plate;  
 the outer surface of the lower annular wall being downwardly tapered such that the outside diameter of the wall increases from the lower end of the barrel to the lower surface of the bearing plate; and  
 
   a tendon extending through the wedge-receiving cavity, the tendon being encased in a sheathing on either side of the cavity, the cavity having a diameter at the lower end of the barrel that is at least as great as the diameter of the sheathing on said tendon.    
   
   
       18 . An intermediate anchor in accordance with  claim 17 , further comprising: 
 at least two wedges in interference fit relationship between the interior wall of the wedge-receiving cavity and an exterior surface of an unsheathed portion of the tendon.    
   
   
       19 . An intermediate anchor in accordance with  claim 18 , wherein when the wedges have a height of about 1.25″ and an outside taper of about 7°, then the wedge-receiving cavity has a height from the upper end of the barrel to the lower end of the barrel that is within the range from about 1.25″ to about 1.30″, and the wedge-receiving cavity has an angle of taper that is within the range from about 6.5° to about 7.5°.  
   
   
       20 . An intermediate anchor in accordance with  claim 17 , wherein the upper surface of the bearing plate is disposed near the midpoint of the barrel, the distance from the upper end of the barrel to the upper surface of the bearing plate being within the range from about 46% to about 54% of the distance from the upper end of the barrel to the lower end of the barrel.