Patent Description:
The present disclosure relates to equipment for post-tensioned stressed concrete members.

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

Prestressed concrete is structural concrete in which internal stresses are introduced to reduce potential tensile stresses in the concrete resulting from applied loads; this can be accomplished by two methods-post-tensioned prestressing and pre-tensioned prestressing. In a post-tensioned member, the prestressing member is tensioned after the concrete has attained a specified strength. In post-tensioning applications, the prestressing assembly, commonly known as a tendon, may include for example and without limitation, anchorages, the prestressing member, and sheathes or ducts. For the purposes of this disclosure, the prestressing member will be referred to as a "cable", although one having ordinary skill in the art with the benefit of this disclosure will understand that the prestressing member could be any suitable material exhibiting tensile strength which can be elongated including, for example and without limitation, reinforcing steel, single or multi strand cable. One having ordinary skill in the art with the benefit of this disclosure will likewise understand that the prestressing member may be formed from a metal or composite without deviating from the scope of this disclosure. The tendon generally includes an anchorage at each end. The cable is generally fixedly coupled to a fixed anchorage positioned at one end of the tendon, the so-called "fixed-end", and is adapted to be stressed at the other anchor, the "stressing-end" of the tendon.

In order to allow access to the stressing-end of the tendon once the concrete member is poured, a pocket former may be utilized to, for example, prevent concrete from filling in the area between the stressing-end anchor and the concrete element used to form the concrete member. As understood in the art, the concrete element may be a form or mold into which concrete is poured or otherwise introduced into to give shape to the concrete as it sets or hardens thus forming the concrete member. Once the concrete has sufficiently hardened and the form is removed, the pocket former is removed from the concrete member. Generally, pocket formers are frustoconical in shape to, for example, allow for easier removal from the concrete member. Typically, once the tendon is stressed, the pocket formed by the pocket former is filled with a material such as a cementitious chloride-free grout or concrete to, for example, provide fire protection and corrosion protection.

Document <CIT> discloses a permanent cap for use with a post-tensioned concrete anchor according to the preamble of claim <NUM>.

The present disclosure provides for a permanent cap for a post-tensioned concrete anchor positioned in a cavity in a concrete member. The permanent cap includes a cap body. The cap body is adapted to couple to and fluidly seal to the post tensioned concrete anchor. The permanent cap further includes a grout retention feature adapted to retain a filling material within the cavity.

The present disclosure also provides for a method of forming a post-tensioned concrete member. The method includes positioning a post-tensioning tendon within a concrete element. The post-tensioning tendon includes a tension member, fixed anchor, and a stressing end anchor. The method further includes positioning a pocket former between the stressing end anchor and the concrete element. The pocket former is adapted to form a void in the concrete between the stressing end anchor and the concrete element. The method further includes placing concrete into the concrete element such that the post-tensioning tendon and pocket former are encased in cement; removing the pocket former from the cement; and coupling a permanent stressed end cap to the stressing end anchor. The permanent stressed end cap includes a cap body. The cap body is adapted to couple to and fluidly seal to the stressing end anchor. The permanent stressed end cap also includes a grout retention feature adapted to retain a filling material within the void. The method further includes filling the void with a filling material such that the filling material substantially fills the void around the grout retention feature.

The present disclosure is best understood from the following detailed description when read with the accompanying figures.

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting.

When stressing post-tensioned concrete members, anchoring systems may be provided to hold the post-tensioning tendon both before and after stressing. In some embodiments, as depicted in <FIG>, post-tensioning tendon <NUM> may be positioned within concrete element <NUM>. Post-tensioning tendon <NUM> may include for example and without limitation fixed end anchor <NUM>, tension member <NUM>, and stressing end anchor <NUM>. In some embodiments, post-tensioning tendon <NUM> may also include a sheath (not shown) positioned about tension member <NUM> and one or more seals (not shown) between the sheath and each anchor. The sheath and seals may, for example, protect tension member <NUM> from corrosion after concrete <NUM> (shown in <FIG>) is poured. Additionally, the sheath and seals may, for example, prevent concrete from ingressing into tension member <NUM> and preventing or retarding its tensioning as discussed below. In some embodiments, a seal for fixed end anchor <NUM> may be omitted. As depicted in <FIG>, in some embodiments, fixed end anchor <NUM> may be positioned within concrete element <NUM> such that it will be completely encased in concrete <NUM>. According to the invention, fixed end cap <NUM> are positioned at the end of fixed end anchor <NUM> to, for example, protect tension member <NUM> from corrosion after concrete <NUM> is poured.

Stressing end anchor <NUM> may be positioned within concrete element <NUM> such that it is substantially surrounded by concrete <NUM>. Pocket former <NUM> may be positioned between the end of stressing end anchor <NUM> and concrete element <NUM>. Pocket former <NUM> may be adapted to, for example and without limitation, prevent concrete <NUM> from filling the space between stressing end anchor <NUM> and the edge of the resultant concrete member formed by concrete <NUM> within form <NUM>. Pocket former <NUM> may thus allow access to tension member <NUM> from without the concrete member once it is sufficiently hardened and concrete element <NUM> is removed.

In some embodiments, as depicted in <FIG>, pocket former <NUM> may include pocket former body <NUM>. In some embodiments, pocket former body <NUM> may include a coupler (not shown) for coupling pocket former <NUM> to stressing end anchor <NUM>. In some embodiments, pocket former body <NUM> may be generally hollow. As depicted in <FIG>, pocket former body <NUM> may be frustoconical. In some embodiments, by tapering pocket former body <NUM> inward from the edge of concrete <NUM>, removal of pocket former body <NUM> from concrete <NUM> may, for example and without limitation, be accomplished more easily. As depicted in <FIG>, when pocket former body <NUM> is removed from concrete <NUM> (once concrete <NUM> has reached a sufficient strength), cavity <NUM>' is left in concrete <NUM> corresponding with the outside shape of pocket former body <NUM>.

In some embodiments, once pocket former body <NUM> is removed from concrete <NUM>, tension member <NUM> may be placed under tensile stress. In some embodiments, stressing end anchor <NUM> may be adapted to allow tension member <NUM> to extend in length and be stressed against fixed end anchor <NUM> (now embedded in cement <NUM>), while preventing retraction of tension member <NUM> once stressed. In some embodiments, tension member <NUM> may be cut to length such that it does not, for example, extend beyond the edge of concrete <NUM>. In some embodiments, once sufficient tension has been applied, cavity <NUM>' may, as depicted in <FIG>, be filled with filling material <NUM>. Filling material <NUM> may, as understood in the art, be grout, a cementitious chloride-free grout, or concrete. According to the invention, permanent stressed end cap <NUM> are installed over the end of tension member <NUM> to, for example and without limitation, prevent filling material <NUM> from entering stressed end anchor <NUM> and tension member <NUM>.

According to the invention, permanent stressed end cap <NUM> includes cap body <NUM>. Cap body <NUM> may be generally cylindrical in shape, although one having ordinary skill in the art with the benefit of this disclosure will understand that cap body <NUM> may be any shape. In some embodiments, cap body <NUM> may be generally hollow, allowing cap body <NUM> to fit over the end of tension member <NUM>. In some embodiments, cap body <NUM> may be filled with grease. In some embodiments, permanent stressed end cap <NUM> may include coupler <NUM> adapted to couple permanent stressed end cap <NUM> to stressed end anchor <NUM>. Coupler <NUM> may include, for example and without limitation, a threaded connection, press-fit connection, bayonet connection, or any other suitable coupler for coupling permanent stressed end cap <NUM> to stressed end anchor <NUM>. In some embodiments, one or more seals (not shown) may be included to, for example, fluidly seal between stressed end cap <NUM> and stressed end anchor <NUM>. In some embodiments, coupler <NUM> may be a separate part from stressed end cap <NUM> and installed to stressed end cap <NUM> and stressed end anchor <NUM> after stressed end cap <NUM> is in position.

According to the invention, as depicted in <FIG>, permanent stress end cap <NUM> includes a grout retention feature <NUM>. Grout retention feature <NUM> provides more surface area and/or one or more locking features into which filling material <NUM> may fill, thus, for example and without limitation, preventing filling material <NUM> from delaminating or otherwise coming loose from or moving relative to concrete <NUM>.

As depicted in <FIG>, according to the invention, grout retention feature <NUM> extends past the end of cap body <NUM>. As depicted in detail in <FIG>, grout retention feature <NUM> is coupled to cap body <NUM> by a neck <NUM>. In some embodiments, grout retention feature <NUM> may be generally rounded or toroidal in shape as depicted in <FIG>, <FIG>. In some embodiments, as depicted in <FIG>, grout retention feature <NUM> may be generally polygonal in shape. One having ordinary skill in the art with the benefit of this disclosure will understand that grout retention feature <NUM> may have any shape suitable for retaining filling material <NUM> within cavity <NUM>', and may include without limitation, round, square, polygonal, mushroom-shaped, toroidal, ellipsoidal, spherical, or prismatoidal.

According to the invention, as depicted in <FIG>, grout retention feature <NUM> includes one or more locking features. According to the invention, locking features includes textured surfaces, ridges, grooves, recesses, or protrusions from or into grout retention feature <NUM> adapted to prevent movement of filling material <NUM> relative to concrete <NUM>. For example, <FIG> depicts multiple protrusions <NUM> extending from grout retention feature <NUM>. One having ordinary skill in the art with the benefit of this disclosure will understand that protrusions <NUM> from grout retention feature <NUM> may be of any shape, including but not limited to, cylindrical, prismatoidal, ellipsoidal, or any combination thereof.

According to the invention, grout retention feature <NUM> further includes a surface texture (not shown). One having ordinary skill in the art with the benefit of this disclosure will understand that the surface texture is a pattern including cross hatched, grooved, stippled, ridged, knurled, fluted, or any combination thereof. The surface texture may be formed as protrusions from grout retention feature <NUM>, as depressions into grout retention feature <NUM>, or any combination thereof.

In some embodiments, as depicted in <FIG>, grout retention feature <NUM> may be formed as an integral part of cap body <NUM>.

Claim 1:
A permanent cap (<NUM>) for use with a post-tensioned concrete anchor (<NUM>) that is positioned in a cavity (<NUM>') in a concrete member, the permanent cap, comprising:
a cap body (<NUM>), the cap body adapted to couple to the post tensioned concrete anchor; and
a grout retention feature (<NUM>) adapted to retain a filling material within the cavity, the grout retention feature comprises a grout retention feature body coupled to the cap body by a neck (<NUM>) and wherein the grout retention feature comprises a surface texture, wherein the surface texture comprises at least one of cross hatches, grooves, stipples, ridges, knurls, flutes, or any combination thereof;
the permanent cap being characterized in that
the grout retention feature extends from an end of the cap body opposite the post-tensioned concrete anchor.