Spindle lock anchor for post tensioned concrete member

1. An anchor for a post-tensioning tendon comprising a strand encased in a sheath, the anchor comprising:

an anchor body, the anchor body having an internal passage therethrough;

a lock nut, the lock nut having an internal tapered surface defining a forcing cone; and

a spindle, the spindle positioned within the internal passage and threadedly coupled to the lock nut, the spindle having an expansion wedge corresponding to the forcing cone;

wherein the expansion wedge and the forcing cone cooperate to grip the sheath therebetween.

2. The anchor of claim 1 , wherein the spindle further comprises a spindle extension, the spindle extension, the spindle extension having an external thread, the external thread threadedly coupling the spindle extension with a spindle nut.

3. The anchor of claim 1 further comprising a gasket positioned between the lock nut and the anchor body.

4. The anchor of claim 1 , wherein the spindle further comprises a retention feature, the retention feature being an edge, detent, extension, or retaining profile.

5. The anchor of claim 1 , wherein the anchor is a fixed end anchor, a stressing end anchor, or an intermediate anchor.

6. The anchor of claim 1 , wherein at least one of the expansion wedge or the forcing cone has a grip enhancing surface feature, wherein the grip enhancing surface feature includes teeth or grooves.

7. The anchor of claim 1 , wherein the spindle is formed from a non-conductive material.

8. A post-tensioning tendon comprising:

a tension member comprising a strand and a sheath, the sheath positioned about the strand;

a first anchor coupled to a first end of the tension member, and a second anchor coupled to a second end of the tension member, each anchor including:

an anchor body, the anchor body having an internal passage;

a lock nut, the lock nut having an internal tapered surface defining a forcing cone, the lock nut coupled to the anchor body; and

a spindle, the spindle positioned within the internal passage and threadedly coupled to the lock nut, the spindle having an expansion wedge, the sheath gripped between the expansion wedge and the forcing cone.

9. The post-tensioning tendon of claim 8 , wherein the spindle of at least one of the first or second anchor further comprises a spindle extension, the spindle extension having an external thread, the spindle extension threadedly coupled with a spindle nut by the external thread, the spindle extension threaded through a strand aperture in an end wall of a concrete form, the anchor body coupled to the end wall by the spindle nut.

10. The post-tensioning tendon of claim 9 further comprising a pocket former, the pocket former positioned between the anchor body of the first or second anchor and the end wall.

11. The post-tensioning tendon of claim 8 , further comprising a gasket positioned between the lock nut and the anchor body of at least one of the first or second anchor.

12. The post-tensioning tendon of claim 8 further comprising a fixed end cap, the fixed end cap positioned at the distal end of either the first or second anchor.

13. The post-tensioning tendon of claim 8 , wherein at least one of the expansion wedge or the forcing cone of at least one of the first or second anchor has a grip enhancing surface feature, wherein the surface feature includes teeth or grooves.

14. The post-tensioning tendon of claim 8 , wherein the spindle and the anchor body are formed from different materials.

15. A method of coupling a tension member to an anchor for forming a post-tensioning tendon comprising:

providing a tension member comprising a strand and a sheath, the sheath being positioned about the strand;

providing an anchor, the anchor including:

an anchor body, the anchor body having an internal passage;

a lock nut, the lock nut having an internal tapered surface defining a forcing cone, the lock nut coupled to the anchor body; and

a spindle, the spindle positioned within the internal passage and threadedly coupled to the lock nut, the spindle having an expansion wedge, the sheath gripped between the expansion wedge and the forcing cone;

removing a portion of a first end of the sheath from a first end of the tension member exposing a first end of the strand;

inserting the first end of the tension member into the anchor;

inserting the first end of the strand through the spindle;

inserting the sheath between the expansion wedge and the forcing cone;

tightening the lock nut onto the spindle such that the sheath is compressed between the expansion wedge and the forcing cone; and

coupling the strand to the anchor.

16. The method of claim 15 , wherein the spindle further comprises a spindle extension, the spindle extension threaded through a strand aperture in an end wall of a concrete form, the anchor body coupled to the end wall by the spindle nut, and wherein the method further comprises the operations of:

positioning the spindle extension through the end wall;

threading the spindle nut onto the spindle extension such that the anchor body is coupled to the end wall.

17. The method of claim 16 further comprising:

filling the concrete element with concrete;

setting the concrete;

disengaging the spindle from the lock nut; and

removing the spindle from the anchor body.

18. The method of claim 15 further comprising electrically insulating the strand and the anchor using the spindles.

19. The method of claim 15 further comprising positioning seals between the lock nut and the anchor.

20. The method of claim 15 further comprising preventing the spindle from being pulled through the anchor body using a retention feature.