Patent Description:
The present disclosure relates to an apparatus for use in post-tensioning concrete.

Many structures are built using concrete, including, for instance, buildings, parking structures, apartments, condominiums, hotels, mixed-use structures, casinos, hospitals, medical buildings, government buildings, research/academic institutions, industrial buildings, malls, bridges, pavement, tanks, reservoirs, silos, foundations, sports courts, and other structures.

The concrete may be poured into a concrete form. The concrete form may be a form or mold to give shape to the concrete as the concrete sets or hardens, thus forming a concrete member.

Prestressed concrete is structural concrete in which internal stresses are introduced to reduce potential tensile stresses in the concrete resulting from applied loads; prestressing may be accomplished by post-tensioned prestressing or pre-tensioned prestressing. In post-tensioned prestressing, a post-tensioning tendon embedded in the concrete is tensioned after the concrete has attained a specified strength. A post-tensioning tendon may include for example and without limitation, anchorages, the tension member, and sheathes or ducts.

A post-tensioning tendon generally includes an anchorage at each end. The tension member is fixedly coupled to a fixed anchor positioned at one end of the post-tensioning tendon, sometimes referred to as the "fixed-end" or "dead end" anchor, and is stressed at the other anchor, sometimes referred to as the "stressing-end" or "live end" anchor.

The tension member may be constructed of a material that is suitable for post-tensioning, such as, for example, reinforcing steel or composite material in the form of single or multi-strand cable. A post-tensioning tension member is typically provided in a protective sheath. The sheath may be polymeric and may contain a protective fluid, such as grease, in addition to the tension member. The purpose of the sheath and protective fluid, if present, is to inhibit air, water, and other corrosive substances from contacting the tension member.

The tension member is stressed by pulling the tension member through the stressing anchor; when the pulling force is released, the anchors grip the tension member and retain the tension member in tension. In some instances, the anchors grip the tension member using wedges, so that the gripping force increases when the tension on the tension member increases. <CIT> discloses a concrete tendon gripping and sealing apparatus.

A sheathing repair assembly for a tension member of a post-tensioning tendon may comprise an outer tube having first and second end portions, a tubular long seal positioned inside the outer tube, a first seal positioned in the first end portion of the outer tube, a second seal positioned in the second end portion of the outer tube, a first nut retaining the first seal in the first end portion of the outer tube, and a second nut retaining the second seal in the second end portion of the outer tube.

The sheathing repair assembly further comprises an inner tube positioned between the outer tube and the tubular long seal. The first seal may be configured such that mechanically coupling the first nut to the outer tube causes the first seal to fill an annular space defined between the outer tube, the tubular long seal, the tension member, and the first nut, and the second seal may be configured such that mechanically coupling the second nut to the outer tube causes the second seal to fill an annular space defined between the outer tube, the tubular long seal, the tension member, and the second nut.

The outer tube may not have a longitudinal slit. The first and second seals may each have a longitudinal slit. The tubular long seal may have a longitudinal slit.

The tension member may have an unsheathed portion and the tubular long seal may be long enough to fully cover the unsheathed portion. The tubular long seal may be long enough to extend beyond the unsheathed portion.

A method for repairing an unsheathed portion of a sheathed tension member, may comprise the steps of: a) providing a sheathing repair assembly comprising an outer tube having first and second end portions, a tubular long seal sized to fit onto the tension member, a first seal sized to fit onto the tension member, a second seal sized to fit onto the tension member, a first nut adapted to mechanically couple to one end portion, and a second nut adapted to mechanically couple to one end portion, b) positioning the tubular long seal at the unsheathed portion, c) positioning the outer tube around the tubular long seal, d) inserting the first seal into the first end portion and coupling the first nut to the first end portion so as to retain the first seal therein, e) inserting the second seal into the second end portion and coupling the second nut to the second end portion so as to retain the second seal therein. The method further includes the step of positioning an inner tube between the tubular long seal and the outer tube before step d). The method may further include the step of removing the inner tube from between the tubular long seal and the outer tube before step d).

The Figure shows a cross-sectional view of a sheathing repair assembly consistent with at least one embodiment of the present disclosure.

Referring to the Figure, sheathing repair assembly <NUM> in accordance with some embodiments may include outer tube <NUM> having first and second end portions <NUM>, <NUM>, tubular long seal <NUM>, first and second seals <NUM>, <NUM> positioned in first end portion <NUM> and second end portion <NUM> of outer tube <NUM>, respectively, and first and second nuts <NUM>, <NUM> each retaining first and second seals <NUM>, <NUM> in first and second end portions of outer tube <NUM>. Sheathing repair assembly <NUM> may be used to repair a tension member such as tension member <NUM> where sheathing <NUM> is damaged or discontinuous. In one embodiment, a sheathing repair assembly may include inner tube <NUM>.

Outer tube <NUM> may be made of an elastomeric polymer. Outer tube <NUM> may be positioned over tension member <NUM> by sliding outer tube <NUM> from an end of the tension member to a location on the tension member. In some embodiments, each end portion <NUM>, <NUM> of outer tube <NUM> may include engagement feature <NUM>, such as threads, bayonet tabs or a groove or ridge, to facilitate engagement with first and second nuts <NUM>, <NUM>. In some embodiments, outer tube <NUM> may be provided without an engagement feature. In some embodiments, the inside diameter of outer tube <NUM> may be greater than the outside diameter of tubular long seal <NUM>. In some embodiments, the inside diameter of outer tube <NUM> may be less than the outside diameter of tubular long seal <NUM>. In some embodiments, the inside diameter of outer tube <NUM> may be substantially the same as the outside diameter of tubular long seal <NUM>.

Tubular long seal <NUM> may be made of elastomeric polymer and may comprise a compressible elastomer. Tubular long seal <NUM> may be split longitudinally. Tubular long seal <NUM> may be applied from the side of tension member <NUM> by passing tension member <NUM> through the slit in tubular long seal <NUM>, so that access to the end of tension member <NUM> is not required. Tubular long seal <NUM> may be sized to receive tension member <NUM> therein. In some embodiments, the inside diameter of tubular long seal <NUM> may be less than the outside diameter of tension member <NUM> so that the inner surface of tubular long seal <NUM> conforms to the outer surface of the tension member <NUM>. In some embodiments, the inside diameter of tubular long seal <NUM> may be substantially the same as the outside diameter of tension member <NUM>. In the embodiment depicted in the Figure, tubular long seal <NUM> is shorter than outer tube <NUM>.

Inner tube <NUM> may be made of an elastomeric or non-elastomeric polymer, or a metal. In one embodiment, inner tube <NUM> may have a longitudinal split and may be applied from the side of the tension member. In another embodiment, inner tube <NUM> may have no split and may be positioned on the tension member by sliding inner tube <NUM> from the end of the tension member to a desired position. At least one end portion of inner tube <NUM> may include a hole, tab, or other feature to facilitate movement of inner tube <NUM>. Inner tube <NUM> may be applied to the outside of tubular long seal <NUM> after tubular long seal <NUM> is applied to tension member <NUM> and before outer tube <NUM> is applied to the outside of tubular long seal <NUM>. Inner tube <NUM> may facilitate the passage of tubular long seal <NUM> into outer tube <NUM>, such as by radially compressing tubular long seal <NUM> or decreasing friction between tubular long seal <NUM> and outer tube <NUM>. Inner tube <NUM> may protect tubular long seal <NUM> until outer tube <NUM> is applied to the outside of tubular long seal <NUM>. The inside diameter of inner tube <NUM> may be substantially the same as or less than the outside diameter of tubular long seal <NUM>. The outside diameter of inner tube <NUM> may be substantially the same as the inside diameter of outer tube <NUM>. The outside diameter of inner tube <NUM> may be less than the inside diameter of outer tube <NUM>.

First and second seal <NUM>, <NUM> may be made of elastomeric polymer and may be split longitudinally. First and second seal <NUM>, <NUM> may be applied from the side of tension member <NUM> by passing tension member <NUM> through the slit, so that access to the end of the tension member is not required. As shown in the Figure, when applied, first seal <NUM> is positioned in first end portion <NUM> of outer tube <NUM>. Similarly, second seal <NUM> is positioned in second end portion <NUM> of outer tube <NUM>.

Each of first and second nuts <NUM>, <NUM> may mechanically engage outer tube <NUM> at engagement feature <NUM> at first end portion <NUM> and second end portion <NUM>, respectively, of outer tube <NUM>, and may include corresponding internal threads, bayonet tabs or a ridge or groove. In some embodiments, first and second nuts <NUM>, <NUM> may be self-tapping nuts that create threads when threaded onto outer tube <NUM>. In some embodiments, each of first and second nuts <NUM>, <NUM> is a threaded or self-tapping nut engaged with outer tube <NUM>.

In operation, when it is desired to repair an unsheathed portion of tension member <NUM>, tubular long seal <NUM> is applied to the unsheathed portion. Tubular long seal <NUM> may be applied to tension member <NUM> at the unsheathed portion or may be applied elsewhere on the length of tension member <NUM> and slid along tension member <NUM> to the desired location. Tubular long seal <NUM> may be long enough to fully cover and, optionally, extend beyond the unsheathed portion of tension member <NUM> or, if a portion of sheathing <NUM> has been removed, tubular long seal <NUM> may be positioned between the ends of sheathing <NUM>.

Inner tube <NUM> may be applied to the outside of tubular long seal <NUM> after tubular long seal <NUM> is applied to the tension member <NUM> and before or after tubular long seal <NUM> is positioned at the unsheathed portion thereof. Inner tube <NUM> may already be present on tension member <NUM> or may be applied from the end of tension member <NUM>.

Outer tube <NUM> may already be present on tension member <NUM> or may be applied from the end of tension member <NUM>. First and second nuts <NUM>, <NUM> may already be present or may be applied from the end of tension member <NUM>. First and second nuts <NUM>, <NUM> may be provided separately from outer tube <NUM> or may be engaged with outer tube <NUM> when applied to tension member <NUM>. Outer tube <NUM> is positioned at a desired location on tension member <NUM>. If first and second nuts <NUM>, <NUM> are engaged with outer tube <NUM>, first and second nuts <NUM>, <NUM> may be decoupled from outer tube <NUM> before proceeding.

In some embodiments, tubular long seal <NUM>, inner tube <NUM>, outer tube <NUM>, and, optionally, first and second nuts <NUM>, <NUM> may all be applied to a tension member <NUM> and then slid along the tension member <NUM> to a desired location on the tension member <NUM>. In some embodiments, tubular long seal <NUM>, inner tube <NUM>, outer tube <NUM>, and, optionally, first and second nuts <NUM>, <NUM> may each be separately applied to a desired location on tension member <NUM>. Some or all of the components of sheathing repair assembly <NUM> may be pre-assembled prior to delivery to the pour site or may be assembled at the pour site. For example, inner tube <NUM>, outer tube <NUM>, and first and second nuts <NUM>, <NUM> may be preassembled. First and second seals <NUM>, <NUM> may be but are not necessarily included in the pre-assembly. If first and second seals <NUM>, <NUM> are included in pre-assembly, at least one of first and second seals <NUM>, <NUM> may be removed from outer tube <NUM> before outer tube <NUM> is slid over tubular long seal <NUM>.

With tubular long seal <NUM> and inner tube <NUM> positioned at the desired location on tension member <NUM>, outer tube <NUM> may be slid along the tension member so that tubular long seal <NUM> and inner tube <NUM>, if present, are received therein. If it is desired to remove inner tube <NUM> before completing the repair operation, inner tube <NUM> may be removed before first and second seal <NUM>, <NUM> are inserted.

First and second seal <NUM>, <NUM> are then inserted or re-inserted into first and second end portions of outer tube <NUM> and first and second nuts <NUM>, <NUM> are mechanically coupled to the first and second end portions of outer tube <NUM>, respectively. Each of first and second nuts <NUM>, <NUM> retains and compresses first and second seal <NUM>, <NUM>, respectively. Each of first and second seal <NUM>, <NUM> deforms so as to fill voids in the annular space defined between tension member <NUM>, tubular long seal <NUM>, outer tube <NUM> or inner tube <NUM>, and first and second nuts <NUM>, <NUM>. In some embodiments, each of first and second seals <NUM>, <NUM> is configured such that when first and second nuts <NUM>, <NUM> fully engage outer tube <NUM>, there may be no substantial voids in the annular space. In other embodiments, each of first and second seal <NUM>, <NUM> is configured such that when first and second nuts <NUM>, <NUM> fully engage outer tube <NUM>, there may be substantially no voids in the annular space. In one embodiment, each nut <NUM>, <NUM> may be tightened until fully engaged. In other embodiments, each nut <NUM>, <NUM> is a self-tapping nut and may be tightened until the self-tapping nut bottoms out or begins to plastically deform. In another embodiment, each nut <NUM>, <NUM> may be tightened until sealing occurs. In another embodiment, each nut <NUM>, <NUM> may be tightened to a position to inhibit seepage of fluids that might corrode the strand.

When assembled, sheathing repair assembly <NUM> defines a longitudinal passage that is adapted to receive tension member <NUM> and sealingly engage the outer surface thereof. The presence of the sheathing repair assembly <NUM> on tension member <NUM> seals the portion of the tension member that is within the assembly, i.e. between first and second nuts <NUM>, <NUM>.

In each embodiment and each method described herein, repair of sheathing <NUM> may be for the purpose of re-sealing sheathing <NUM> that has become damaged or replacement of a sheathing layer on a portion of strand from which sheathing <NUM> has been removed to prevent the ingress of fluid into tension member <NUM>.

Claim 1:
A sheathing repair assembly for a tension member of a post-tensioning tendon, the sheathing repair assembly comprising:
an outer tube (<NUM>) having first and second end portions:
a tubular long seal (<NUM>) positioned inside the outer tube, wherein the tubular long seal is shorter than the outer tube;
a first seal (<NUM>) positioned in the first end portion of the outer tube;
a second seal (<NUM>) positioned in the second end portion of the outer tube;
a first nut (<NUM>) retaining the first seal in the first end portion of the outer tube;
a second nut (<NUM>) retaining the second seal in the second end portion of the outer tube;
wherein the assembly defines a longitudinal passage adapted to receive the tension member; and,
an inner tube (<NUM>) positioned between the outer tube and the tubular long seal.