Intermediate anchorage for concrete structures

Abstract

An intermediate anchor having a wedge hole is placed at a concrete construction joint. A sheathed tendon is inserted through the intermediate anchor. Following setting of concrete poured on a bearing side of the concrete construction joint, the sheathing of the tendon is cut circumferentially around the tendon in a wedge hole of the tendon. The sheathed tendon is then tensioned. This tensioning creates an exposed portion of the tendon in the wedge hole. A tension holding wedge is placed in the wedge hole so as to grip the exposed portion to hold the tension. Seals on the bearing side and a stressing side of the concrete construction joint seals the exposed portion.

What is claimed is:  
     
         1 . A method comprising: 
 placing an intermediate anchor having a wedge hole at a concrete construction joint;    inserting a tendon through the intermediate anchor leaving a sheathing of the tendon substantially intact;    making a single cut circumferentially around the sheathing inside the wedge hole;    tensioning the sheathed tendon following setting of concrete poured on a bearing side of the concrete construction joint, whereby the tensioning causes the sheathing to pull away from the single cut so as to thereby create an exposed portion of the tendon; and,    gripping the exposed portion with a wedge to hold the tension.    
     
     
         2 . The method of  claim 1  wherein the tensioning of the sheathed tendon comprises applying a gripper wedge to the tendon outside of the intermediate anchor.  
     
     
         3 . The method of  claim 2  wherein application of the gripper wedge damages the sheathing of the tendon, and wherein the method further comprises repairing the damage before pouring concrete on a stressing side of the concrete construction joint.  
     
     
         4 . The method of  claim 3  wherein the repairing of the damage comprises taping.  
     
     
         5 . The method of  claim 1  further comprising attaching an adaptor to the intermediate anchor on the bearing side and inserting an O-ring within the adaptor so as to engage the adaptor and the tendon.  
     
     
         6 . The method of  claim 5  further comprising attaching a bushing to the adaptor so as to bias the O-ring into sealing engagement with the adaptor and the tendon.  
     
     
         7 . The method of  claim 1  further comprising attaching a cap to the intermediate anchor on a stressing side of the construction joint and inserting an O-ring within the cap to engage the cap and the tendon.  
     
     
         8 . The method of  claim 7  further comprising attaching a bushing to the cap so as to bias the O-ring into sealing engagement with the cap and the tendon.  
     
     
         9 . The method of  claim 7  wherein the O-ring has an inner diameter larger than an outer diameter of the tendon.  
     
     
         10 . The method of  claim 1  further comprising: 
 attaching an adaptor to the intermediate anchor on the bearing side;  
 attaching a backside bushing to the adaptor;  
 attaching a cap to the intermediate anchor on a stressing side of the construction joint; and,  
 attaching a frontside bushing to the cap.  
 
     
     
         11 . The method of  claim 10  further comprising: 
 inserting a backside O-ring within the adaptor so as to engage the adaptor and the tendon; and,  
 inserting a frontside O-ring within the cap so as to engage the cap and the tendon.  
 
     
     
         12 . An intermediate anchor system for a tendon comprising: 
 an intermediate anchor having a backside, a frontside, and a wedge hole arranged to receive a wedge; and,    backside and frontside seals at the backside and the frontside, respectively, of the intermediate anchor, wherein the backside and frontside seals are arranged to seal an exposed portion of the tendon within the wedge hole, and wherein the exposed portion of the tendon is confined to the wedge hole.    
     
     
         13 . The intermediate anchor system of  claim 12  wherein the backside seal comprises an adaptor engaging the intermediate anchor and an O-ring engaging the adaptor and the tendon.  
     
     
         14 . The intermediate anchor system of  claim 13  wherein the backside seal further comprises a bushing biasing the O-ring into sealing engagement with the adaptor and the tendon.  
     
     
         15 . The intermediate anchor system of  claim 12  wherein the frontside seal comprises a cap engaging the intermediate anchor and an O-ring engaging the cap and the tendon.  
     
     
         16 . The intermediate anchor system of  claim 15  wherein the frontside seal further comprises a bushing biasing the O-ring into sealing engagement with the cap and the tendon.  
     
     
         17 . The intermediate anchor system of  claim 15  wherein the O-ring has an inner diameter at least somewhat larger than an outer diameter of the tendon.  
     
     
         18 . The intermediate anchor system of  claim 12  wherein the backside seal comprises an adaptor engaging the intermediate anchor and a backside O-ring engaging the adaptor and the tendon, and wherein the frontside seal comprises a cap engaging the intermediate anchor and a frontside O-ring engaging the cap and the tendon.  
     
     
         19 . The intermediate anchor system of  claim 18  wherein the backside seal further comprises a backside bushing biasing the backside O-ring into sealing engagement with the adaptor and the tendon, and wherein the frontside seal further comprises a frontside bushing biasing the frontside O-ring into sealing engagement with the cap and the tendon.  
     
     
         20 . The intermediate anchor system of  claim 12  wherein the frontside seal comprises: 
 a cap engaging the intermediate anchor;  
 an O-ring within the cap and engaging both the cap and the tendon; and,  
 a bushing engaging the cap so as to bias the O-ring into sealing engagement with the cap and the tendon.  
 
     
     
         21 . The intermediate anchor system of  claim 12  wherein the backside seal is on a bearing side of the intermediate anchor system, and wherein the backside seal comprises: 
 an adaptor having an adaptor neck engaging an anchor neck of the intermediate anchor;  
 an O-ring within the adaptor and engaging both the adaptor and the tendon; and,  
 a bushing engaging the adaptor so as to bias the O-ring into sealing engagement with the adaptor and the tendon.  
 
     
     
         22 . The intermediate anchor system of  claim 21  wherein the O-ring is a backside O-ring, wherein the bushing is a backside bushing, and wherein the frontside seal comprises: 
 a cap engaging the intermediate anchor;  
 a frontside O-ring within the cap and engaging both the cap and the tendon; and,  
 a frontside bushing engaging the cap so as to bias the frontside O-ring into sealing engagement with the cap and the tendon.  
 
     
     
         23 . The intermediate anchor system of  claim 12  wherein the backside seal is on a bearing side of the intermediate anchor system, and wherein the backside seal comprises an adaptor and a bushing engaging one another.  
     
     
         24 . The intermediate anchor system of  claim 23  wherein the backside seal further comprises an O-ring biased into sealing engagement with the adaptor and the tendon when the adaptor and the bushing engage one another.  
     
     
         25 . An intermediate anchor system comprising: 
 a tendon having a greased cable within a sheathing, wherein the tendon has an exposed portion, and wherein the exposed portion has no sheathing;    an intermediate anchor having a backside, a frontside, and a wedge hole arranged to receive a wedge, wherein the sheathed tendon extends through the intermediate anchor so that the exposed portion is within the wedge hole;    a wedge within the wedge hole and clamped to the exposed portion of the sheathed tendon;    a backside seal engaging the sheathed tendon at the backside of the intermediate anchor; and,    a frontside seal engaging the sheathed tendon at the frontside of the intermediate anchor, wherein the backside and frontside seals seal the exposed portion of the sheathed tendon.    
     
     
         26 . The intermediate anchor system of  claim 25  wherein the backside seal comprises an adaptor engaging the intermediate anchor and an O-ring engaging the adaptor and the tendon.  
     
     
         27 . The intermediate anchor system of  claim 26  wherein the backside seal further comprises a bushing biasing the O-ring into sealing engagement with the adaptor and the tendon.  
     
     
         28 . The intermediate anchor system of  claim 25  wherein the frontside seal comprises a cap engaging the intermediate anchor and an O-ring engaging the cap and the tendon.  
     
     
         29 . The intermediate anchor system of  claim 28  wherein the frontside seal further comprises a bushing biasing the O-ring into sealing engagement with the cap and the tendon.  
     
     
         30 . The intermediate anchor system of  claim 28  wherein the O-ring has an inner diameter larger than an outer diameter of the tendon.  
     
     
         31 . The intermediate anchor system of  claim 25  wherein the backside seal comprises an adaptor engaging the intermediate anchor and a backside O-ring engaging the adaptor and the tendon, and wherein the frontside seal comprises a cap engaging the intermediate anchor and a frontside O-ring engaging the cap and the tendon.  
     
     
         32 . The intermediate anchor system of  claim 31  wherein the backside seal further comprises a backside bushing biasing the backside O-ring into sealing engagement with the adaptor and the tendon, and wherein the frontside seal further comprises a frontside bushing biasing the frontside O-ring into sealing engagement with the cap and the tendon.  
     
     
         33 . The intermediate anchor system of  claim 25  wherein the backside seal comprises: 
 an adaptor engaging the intermediate anchor;  
 an O-ring within the adaptor and engaging both the adaptor and the tendon; and,  
 a bushing engaging the adaptor so as to bias the O-ring into sealing engagement with the adaptor and the tendon.  
 
     
     
         34 . The intermediate anchor system of  claim 33  wherein the O-ring is a backside O-ring, wherein the bushing is a backside bushing, and wherein the frontside seal comprises: 
 a cap engaging the intermediate anchor;  
 a frontside O-ring within the cap and engaging both the cap and the tendon; and,  
 a frontside bushing engaging the cap so as to bias the frontside O-ring into sealing engagement with the cap and the tendon.  
 
     
     
         35 . The intermediate anchor system of  claim 25  wherein the frontside seal comprises: 
 a cap engaging the intermediate anchor;  
 an O-ring within the cap and engaging both the cap and the tendon; and,  
 a bushing engaging the cap so as to bias the O-ring into sealing engagement with the cap and the tendon.  
 
     
     
         36 . A method comprising: 
 placing an intermediate anchor having a wedge hole at a concrete construction joint;    inserting a tendon through the intermediate anchor leaving a sheathing of the tendon substantially intact;    sealing the intermediate anchor on a bearing side of the concrete construction joint;    making a cut circumferentially around the sheathing in the wedge hole;    tensioning the sheathed tendon following setting of concrete poured on the bearing side of the concrete construction joint, thereby creating an exposed portion of the tendon;    gripping the exposed portion with a wedge to hold the tension; and,    sealing the intermediate anchor on a stressing side of the concrete construction joint.    
     
     
         37 . The method of  claim 36  wherein the sealing of the intermediate anchor on the bearing side of the concrete construction joint comprises attaching an adaptor to the intermediate anchor on the bearing side and inserting an O-ring within the adaptor so as to engage the adaptor and the tendon.  
     
     
         38 . The method of  claim 37  wherein the sealing of the intermediate anchor on the bearing side of the concrete construction joint further comprises attaching a bushing to the adaptor so as to bias the O-ring into sealing engagement with the adaptor and the tendon.  
     
     
         39 . The method of  claim 36  wherein the sealing of the intermediate anchor on the stressing side of the concrete construction joint comprises attaching a cap to the intermediate anchor on the stressing side and inserting an O-ring within the cap to engage the cap and the tendon.  
     
     
         40 . The method of  claim 39  wherein the sealing of the intermediate anchor on the stressing side of the concrete construction joint further comprises attaching a bushing to the cap so as to bias the O-ring into sealing engagement with the cap and the tendon.  
     
     
         41 . The method of  claim 36  wherein the sealing of the intermediate anchor on the bearing and stressing sides of the concrete construction joint comprises: 
 attaching an adaptor to the intermediate anchor on the bearing side and inserting a backside O-ring within the adaptor so as to engage the adaptor and the tendon; and,  
 attaching a cap to the intermediate anchor on the stressing side and inserting a frontside O-ring within the cap so as to engage the cap and the tendon.  
 
     
     
         42 . The method of  claim 41  further comprising: 
 attaching a backside bushing to the adaptor so as to bias the backside O-ring into sealing engagement with the adaptor and the tendon; and,  
 attaching a frontside bushing to the cap so as to bias the frontside O-ring into sealing engagement with the cap and the tendon.  
 
     
     
         43 . The method of  claim 36  wherein the sealing of the intermediate anchor on the bearing side of the concrete construction joint comprises: 
 attaching an adaptor having an adaptor neck to an anchor neck of the intermediate anchor;  
 inserting an O-ring within the adaptor so as to engage both the adaptor and the tendon; and,  
 engaging a bushing to the adaptor so as to bias the O-ring into sealing engagement with the adaptor and the tendon.  
 
     
     
         44 . The method of  claim 36  wherein the sealing of the intermediate anchor on the stressing side of the concrete construction joint comprises: 
 attaching a cap to the intermediate anchor;  
 inserting an O-ring within the cap so as to engage both the cap and the tendon; and,  
 engaging a bushing to the cap so as to bias the O-ring into sealing engagement with the cap and the tendon.  
 
     
     
         45 . The method of  claim 36  wherein the sealing of the intermediate anchor on the bearing and stressing sides of the concrete construction joint comprises: 
 attaching an adaptor having an adaptor neck to an anchor neck of the intermediate anchor on the bearing side;  
 inserting a backside O-ring within the adaptor so as to engage both the adaptor and the tendon;  
 engaging a backside bushing to the adaptor so as to bias the backside O-ring into sealing engagement with the adaptor and the tendon;  
 attaching a cap to the intermediate anchor on the stressing side;  
 inserting a frontside O-ring within the cap so as to engage both the cap and the tendon; and,  
 engaging a frontside bushing to the cap so as to bias the frontside O-ring into sealing engagement with the cap and the tendon.  
 
     
     
         46 . The method of  claim 36  wherein the tensioning of the sheathed tendon comprises applying a jack and a gripper wedge to the tendon.  
     
     
         47 . The method of  claim 36  wherein the sealing of the intermediate anchor on the bearing side of the concrete construction joint comprises: 
 attaching an adaptor to the intermediate anchor on the bearing side; and,  
 engaging a bushing to the adaptor.  
 
     
     
         48 . The method of  claim 36  wherein the sealing of the intermediate anchor on the bearing and stressing sides of the concrete construction joint comprises: 
 attaching an adaptor to the intermediate anchor on the bearing side;  
 engaging a backside bushing to the adaptor;  
 attaching a cap to the intermediate anchor on the stressing side; and,  
 engaging a frontside bushing to the cap.  
 
     
     
         49 . The method of  claim 36  wherein the tensioning of the sheathed tendon damages the sheathing of the tendon, and wherein the method further comprises repairing the damage before pouring concrete on the stressing side of the concrete construction joint.  
     
     
         50 . The method of  claim 49  wherein the repairing of the damage comprises taping.  
     
     
         51 . An intermediate anchor for anchoring a tendon in concrete, the tendon having an outside diameter, the intermediate anchor having an O-ring to provide a seal between the intermediate anchor and the tendon, the O-ring having an inside diameter, the inside diameter of the O-ring being sufficiently larger than the outside diameter of the tendon in order to permit the O-ring to move freely over the tendon during installation.