On a single-strand unbonded post-tension tendon, the live end is the stressing end, where a hydraulic jack pulls the strand to design force and a nosepiece plunger seats the wedges; the dead end is the opposite end, factory-pressed onto the cut-to-length strand so the wedge teeth bite permanently into the steel [S1].
For tendons longer than 120 ft, suppliers commonly ship both ends as live so the field crew can pull from either side and recover the effective force that seating loss would otherwise consume on a single live end [S1]. Anchor plates for single-strand systems typically measure roughly 2 1/2 in. wide by a little over 5 in. tall, with a tapered wedge cavity and serrated hardened-steel wedges that lock the strand by mechanical interlock rather than by grout bond [S1].
Where the two ends sit in the stressing sequence
Post-tension cables arrive on site with the dead end already seated in its anchor plate, while the live end protrudes from the slab edge as an exposed "spaghetti" tail, ready for the jack [S4]. The slab must reach 2,500 to 3,000 psi before cable layout in the sequence, with the generally required compressive strength for stressing between 3,500 and 5,000 psi [S4]. Only after that strength gate is passed does the crew mount the jack on the live end, pull the strand to design elongation and gauge pressure, then lock the wedges.
Because the dead end is grouted and capped after stressing, the live end is the only end where the tendon can be inspected, re-stressed, or de-tensioned during the service life of the slab; the dead end, by design, is a one-time, non-accessible termination [S4].
How each end is loaded and locked
Dead ends are loaded in the shop by a hydraulic press that forces the wedges into the cavity, or by a jack that pulls the wedges and tendon into the cavity like a lobster trap; both methods exceed any field-jack force, which deforms the strand into the wedge teeth and makes the bond effectively permanent [S1]. Live ends are loaded in the field by a hydraulic plunger in the jack nosepiece, which pushes the wedges into the cavity while the strand is held at the target force; once the jack releases, the strand retracts slightly and sucks the wedges deeper, a movement that defines the seating loss on that end [S1].
That field-seating loss is the main reason the live end is a design variable and the dead end is not: every live-end anchorage has to be detailed with extra elongation or force to compensate for the wedge draw-in, while the dead end contributes no such draw-in because its wedges were already seated under press force before the tendon ever saw service load [S1].
Local-zone behavior behind each end
The primary structural difference between end anchorages and interior anchorages is the cracking induced behind the anchorage as a result of local concrete deformation [S2]. Behind a live end, the bursting force and spalling force zones are produced by the jack force at the moment of lock-off, which is the maximum force the tendon will ever see; behind a dead end, the concrete has already crept and shrunk against a near-permanent bearing pressure, so the local zone is in a different strain state by the time the rest of the slab is loaded.
VSL's report on post-tensioned detailing splits end anchorages into single and multiple configurations and treats interior anchorages as a third category because the bursting reinforcement, spiral ties, and confining steel are sized to the specific anchorage geometry and to whether the anchor sits at a slab edge or in the body of the concrete [S2]. Engineers selecting hardware should match the anchorage type (for example VSL types E, EC, L, or H for ends, with separate interior-anchor detailing) to the local-zone reinforcement rather than reusing edge details in the middle of a slab.
Live end, dead end, and intermediate anchor side by side
Three post-tension anchor types show up on elevated decks: dead ends, live ends, and intermediate anchors, the last being a special live-end anchor that can be slid along the tendon and installed mid-slab so the tendons can be stressed in stages as concrete pours are completed [S1]. Comparing the three on four decision criteria clarifies when to specify each.
Loading location: dead end is loaded in the factory, live end in the field, intermediate in the field but mid-slab [S1]. Access after cure: dead end is buried and grouted, live end is accessible only at the stressing pocket, intermediate is buried inside the slab [S4]. Contribution to seating loss: dead end contributes zero, live end contributes the design seating loss, intermediate contributes its own share for each stressing stage [S1]. Typical use case: dead end for short tendons under 120 ft, live end at every slab edge, intermediate anchor where slab pours are broken into stages and formwork must be stripped early [S1].
When the dead end has to become a live end
Long tendons cannot be shipped with one dead end and one live end without losing too much effective force to seating loss, so the convention is to make both ends live when the cut length exceeds about 120 ft [S1]. The same logic applies on retrofits and slab extensions, where a previously dead end may be re-exposed and re-stressed; in those cases the original dead-end wedges have to be released and the anchor reconfigured as a live end before any new jack work.
Site crews also convert a dead end to a live end whenever the as-built tendon length grows beyond the planned cut length, because the extra friction along the longer duct would otherwise eat the jacking force the design assumed at the live end. Reference data on PT cable sizing and stressing windows for elevated slabs is consolidated on the construction machinery and equipment reference page, which links out to jacking-force and elongation calculators used in this kind of re-spec.
Failure modes and inspection points
The most common live-end issue is wedge pull-out, where the strand does not retract enough to seat the wedges and the tendon loses force the moment the jack releases; the most common dead-end issue is wedge slip, where the factory-pressed wedges were undersized for the as-built tendon force and gradually pull toward the cavity mouth under sustained load [S1]. On site, the only post-stressing inspection window for the live end is the stressing pocket before it is grouted; the dead end has no such window, which is why dead-end hardware is over-rated relative to live-end hardware on most supplier data sheets [S4].
Forensic investigations of PT slab distress therefore start at the live-end stressing pocket (wedge marks, strand protrusion, grout condition) and only move to the dead end by destructive exposure if the live end checks out. The general PT slab installation sequence and inspection checkpoints, including the 2,500 to 3,000 psi placement gate and the 3,500 to 5,000 psi stressing gate, are summarized alongside related tendon hardware on the lamps and light fittings reference index used by field engineers cross-referencing PT work with embedded slab utilities.
The next signal worth tracking is the supplier-side standardization of intermediate-anchor hardware for staged pours, since current practice still relies on field-modified live-end plates rather than purpose-built bodies [S1]. Watch for revised ACI 318 Chapter 25 provisions on anchorage-zone reinforcement and any PTI/PT supplier updates that publish explicit seating-loss values for 0.5 in. and 0.6 in. strand, which would let designers drop the conservative over-jacking margins still common on long tendons.
Spec-level background on the components involved: checking and testing apparatus.
See also our earlier report, 2026 Grid and Data Center M&A: From PPAs to Private Power Assets.