EP3118386B1

EP3118386B1 - Wedge for post tensioning tendon

Info

Publication number: EP3118386B1
Application number: EP16179904.4A
Authority: EP
Inventors: Felix L. Sorkin
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-07-17
Filing date: 2016-07-18
Publication date: 2021-08-11
Anticipated expiration: 2036-07-18
Also published as: EP3118386A1

Description

Cross-Reference to Related Applications

This application is a nonprovisional application which claims priority from U.S. provisional application number 62/193,866, filed July 17, 2015 ; U.S. provisional application number 62/193,883 filed July 17, 2015 ; U.S. provisional application number 62/193,898 filed July 17, 2015 ; US non-provisional application number 14/838,779 filed 28 August 2015 ; and PCT application number PCT/US15/47389 .

Technical Field/Field of the Disclosure

The present disclosure relates generally to post-tensioned, pre-stressed concrete construction. The present disclosure relates specifically to wedges for anchors for use therein.

Background of the Disclosure

Many structures are built using concrete, including, for instance, buildings, parking structures, apartments, condominiums, hotels, mixed-use buildings, casinos, hospitals, medical buildings, government buildings, research/academic institutions, industrial buildings, malls, bridges, pavement, tanks, reservoirs, silos, foundations, sports courts, and other structures.
Pre-stressed 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 pre-stressing and pre-tensioned pre-stressing. When post tensioning concrete, the pre-stressing assembly is tensioned after the concrete has attained a specified strength. The pre-stressing assembly, commonly known as a tendon, may include for example and without limitation, anchorages, one or more strands, and sheathes or ducts. The strand is tensioned between anchors which are embedded in the concrete once the concrete has hardened. The strand may be formed from a metal or composite or any suitable material exhibiting tensile strength which can be elongated, including, for example and without limitation, reinforcing steel, single wire cable, or multi-wire cable. The strand is typically 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. The strand is generally held to each anchor by one or more wedges. Typically, anchors include a tapered recess which, when the strand is placed under tension, causes the wedges to further engage the strand. Wedges are typically made of metal. Typically, wedges must be assembled to or threaded onto the end of the strand once the strand is in position in the concrete member. In the case of a bridge or other elevated structure, there is a risk of dropping wedges. Additionally, as strands may extend far from the end of the structure and bend due to gravity, the ability to thread the wedge onto the end of the strand is limited. Furthermore, misalignment between the wedges during installation may damage the strand or result in an insufficient anchor between strand and the anchor.
US2007/014630 discloses a continuity system for a building, designed to compensate for the downward settling of building elements over time, which occurs due to the shrinkage of wooden building members. The continuity system comprises one or more hold-down assemblies each having a stud-connector secured to a generally vertical stud, a generally vertical rod inserted into an opening of the stud connector, a rod-gripping member in toothed engagement with the rod above the opening, and one or more positioning elements exerting a downward force on the rod-gripping member. The rod has a lower portion secured to a stable building element such as the building's foundation. The opening of the stud-connector defines a frustoconical bearing surface on the upper surface of a portion of the stud-connector, or on a gripper support element in some embodiments. The rod-gripping member includes a plurality of gripping portions each having a lower surface defining a circumferential portion of a frustoconical shape sized and adapted to conform with the frustoconical bearing surface of the stud-connector. If the stud and stud-connector settle downward with respect to the rod, the downward force of the positioning element causes teeth of the gripping portions to disengage from circumferential teeth of the rod so that the rod-gripping member moves downward until the lower surfaces of the gripping portions bear against the frustoconical bearing surface of the stud-connector. The radial components of the reaction forces of the frustoconical bearing surface of the stud-connector causes the teeth of the gripping portions to reengage the teeth of the rod. If lateral forces on the building (e.g., earthquake or strong winds) urge the stud and stud-connector upward relative to the rod, the frustoconical bearing surface of the stud-connector exerts radially inward compression forces onto the gripping portions to cause the teeth of the gripping portions to engage the teeth of the rod and thereby substantially prevent the rod-gripping member and stud-connector from moving upward relative to the rod.

Summary

The present disclosure provides for a wedge assembly according to claim 1, for an anchor of a tendon for post tensioning concrete.
The present disclosure also provides for a method according to claim 5.

Brief Description of the Drawings

The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 depicts a cross section of an anchor having a wedge assembly consistent with at least one embodiment of the present disclosure.
FIG. 2 depicts a perspective view of a wedge assembly consistent with at least one embodiment of the present disclosure installed onto a strand.
FIG. 3 depicts a top view of the wedge ring assembly of FIG. 2.
FIGS. 4A, 4B depict a wedge assembly consistent with at least one embodiment of the present disclosure.
FIGS. 5A, 5B, 5C depict a wedge assembly consistent with at least one embodiment of the present disclosure.
FIGS. 5D, 5E depict the wedge ring of FIGS. 5A, 5B, 5C.

Detailed Description

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. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
FIG. 1 depicts anchor 10 for use in post tensioning concrete. Anchor 10 is adapted to receive and couple to strand 12 of tendon 14. Strand 12 may be, for example and without limitation, mono-wire cable, or multi-wire cable. For the purposes of this disclosure, the axis parallel with the length of strand 12 will be referred to as the longitudinal axis of strand 12. Anchor 10 may include anchor body 16 adapted to retain the position of anchor 10 when positioned in formed concrete.
Anchor 10 may couple to strand 12 by the use of one or more wedges 100. Wedges 100 may be substantially wedge shaped and adapted to fit into a tapered recess 18 formed in anchor body 16. Tension on strand 12 may cause wedges 100 to move into tapered recess 18, applying a gripping force on strand 12.
In some embodiments, wedges 100 may be coupleable by wedge ring 101. As depicted in FIG. 2, each wedge 100 may include groove 103. Groove 103 may be formed in the outer surface 105 of wedges 100 and adapted to receive wedge ring 101. Groove 103 may be formed in a plane substantially perpendicular to the longitudinal axis of strand 12. As depicted in FIG. 3, wedge ring 101 may be substantially annular and may be formed from a material capable of elastic deformation. Wedge ring 101 may include gap 107. Gap 107 may allow wedge ring 101 to be slipped into groove 103 of wedges 100 when wedges are positioned about strand 12 as depicted in FIG. 1. Wedges 100 may thus be positioned about strand 12 before being coupled by wedge ring 101, allowing wedges 100 to be coupled to strand 12 without having to thread strand 12 through wedges 100. Once wedges 100 are positioned about strand 12, wedge ring 101 may be installed to gap 107 in a direction substantially perpendicular to the extent of the strand. Wedge ring 101 may retain wedges 100 to strand 12 before tensioning of strand 12 relative to anchor 10. In some embodiments, gap 107 may be a substantially 60° opening.
In some embodiments, wedge ring 101 may include expansion features 109. Expansion features 109 may be positioned at either end of gap 107 to, for example and without limitation, allow the ends of wedge ring 101 to more easily pass over wedges 100 to allow gap 107 to expand when wedge ring 101 is installed to grooves 103 of wedges 100. In some embodiments, as depicted in FIG. 3, the ends of wedge ring 101 may include a recurve portion to facilitate expansion of wedge ring 101. In some embodiments, one or more loops or holes may be utilized to, for example and without limitation, allow a tool such as snap ring pliers to expand wedge ring 101 during installation.
Because wedge ring 101 is capable of being installed from beside wedges 100 when already installed on strand 12, wedge ring 101 does not need to be threaded onto the end of strand 12 before installation to wedges 100. Likewise, wedges 100 may be individually installed to strand 12 rather than being slipped on from the end of strand 12 as in a case where wedges 100 and wedge ring 101 were previously coupled.
In some embodiments, as depicted in FIGS. 4A, 4B, wedges 100 may be adapted be coupled together prior to installation to strand 12 (not shown) and may include guides 111 adapted to assist with coupling wedges 100 to strand 12. Guides 111 may be positioned to, for example and without limitation, assist in expanding gap 107 by forming a tapered surface against which strand 12 may push. A portion of the force between wedges 100 and strand 12 may thus act to separate wedges 100, allowing for strand 12 to more easily enter wedges 100. Guides 111 may be one or more features positioned on at least a portion of outer surface 105 of one or more wedges 100. In some embodiments, guides 111 may, as depicted be chamfered surfaces positioned at an end of wedges 100. One having ordinary skill in the art with the benefit of this disclosure will understand that guides 111 may be any geometry known in the art including, for example and without limitation, one or more chamfers, ramps, curves, fillets, or combinations thereof. Additionally, guides 111 may be formed at locations on wedges 100 other than that shown in the present disclosure without deviating from the scope of the present disclosure.
In some embodiments, wedges 100 may be formed such that once positioned on strand 12 as depicted in FIGS. 5A, 5C, wedges 100 form a clearance fit around strand 12. The clearance fit is depicted as annular space 113 in FIG. 5A and is sufficiently small that although a clearance fit is maintained, wedge ring 101' may retain wedges 100 to strand 12. The clearance fit may allow wedges 100 to more easily slide along strand 12 during installation whether installed from the end of strand 12 or from the side. Once installed to tapered recess 18 as depicted in FIG. 5B, wedges 100 may grip strand 12 as annular space 113 is closed.
In some embodiments, as depicted in FIGS. 5A, 5D, 5E wedge ring 101' may include one or more hooks 115 adapted to maintain the clearance fit between wedges 100 and strand 12 by, for example and without limitation, maintaining separating tension on wedges 100 to maintain gap 107'. When installed to tapered recess 18 as depicted in FIG. 5B, the force applied on wedges 100 by tapered recess 18 may be sufficient to overcome the separating tension of wedge ring 101', allowing wedges 100 to grip strand 12.
The foregoing outlines features of several embodiments so that a person of ordinary skill in the art may better understand the aspects of the present disclosure. Such features may be replaced by any one of numerous equivalent alternatives, only some of which are disclosed herein. One of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. One of ordinary skill in the art should also realize that such equivalent constructions do not depart from the scope of the present disclosure and that they may make various changes, substitutions, and alterations herein without departing from the scope of the present disclosure.

Claims

A wedge assembly for an anchor (10) of a tendon (14) for use in post tensioning concrete comprising:
at least two wedges (100) adapted to fit on an outer surface of a strand (12) of the tendon (14), each wedge (100) including an outer surface (105) having a circumferential groove (103) formed thereon, the groove (103) positioned in a plane substantially perpendicular to the longitudinal axis of the strand (12); and

a wedge ring (101, 101'), the wedge ring (101, 101') adapted to fit into the groove of each wedge (100), to couple the wedges (100) together and to retain the wedges (100) to the strand (12), the wedge ring (101, 101') including a gap;

wherein the wedge ring (101, 101') gap aligns with a space between the wedges (100) such that the wedge assembly can be installed from the side of the strand (12).
The wedge assembly of claim 1, wherein the wedge ring (101, 101') is adapted to be coupled to the groove (103) in a direction substantially perpendicular to the longitudinal axis of the strand (12).
The wedge assembly of claim 1 or claim 2 comprising two wedges (100).
The wedge assembly of any one of claims 1 to 3, wherein the wedge ring (101, 101') further comprises an expansion feature (109) positioned at each end of the wedge ring (101, 101'), the expansion feature (109) adapted to cause the gap to expand as the wedge ring (101, 101') is installed onto the wedge (100); optionally,
wherein the expansion feature (109) comprises:
a recurve portion; and/or,

a hole adapted to operably couple to a snap ring plier.
A method for installing the wedge assembly of claim 1 onto a strand, the method comprising:
providing an anchor (10) for post tensioning concrete;

threading a strand (12) through the anchor (10);

providing at least two wedges (100), each wedge (100) including an outer surface having a circumferential groove (103) formed thereon, the groove (103) positioned in a plane substantially perpendicular with the longitudinal axis of the strand (12);

providing a wedge ring (101, 101'), the wedge ring (101, 101') adapted to fit into the groove (103) of each wedge (100) and to retain the wedge (100) to a strand (12), the wedge ring (101, 101') including a gap adapted to allow the wedge ring (101, 101') to be installed into the groove (103) of the wedge (100);

installing the wedge ring (101, 101') into the groove (103) of the wedges (100) by expanding the gap of the wedge ring (101, 101') and positioning the wedge ring (101, 101') into the groove (103) so as to couple the wedge ring (101, 101') to the wedges (100); and

installing the coupled wedges (100) and wedge ring (101, 101') to the strand (12) in a direction perpendicular to the longitudinal axis of the strand (12).
The method of claim 5, wherein the wedge ring (101, 101') gap aligns with a space between the wedges (100).
The wedge assembly of claim 1, wherein: the wedge ring (101, 101') retains the wedges (100) to the strand (12) while allowing a clearance fit between the wedges (100) and the strand (12) when the wedges (100) are installed to the strand (12).
The wedge assembly of claim 1 or claim 7, wherein the wedge ring (101, 101') further comprises one or more hooks (115) adapted to elastically retain a radial space between the wedges (100) and the strand (12) to maintain the clearance fit on the strand (12); optionally,
wherein, once installed to the anchor (10), the wedges (100) couple to the outer surface of the strand (12).
The method of claim 6, wherein:
the wedge ring (101, 101') is adapted to fit into the grooves of the wedges (100) and to retain the wedges (100) to the strand (12) while allowing a clearance fit between the wedges (100) and the strand (12) when the wedges (100) are installed to the strand (12); and

further including maintaining the clearance fit between the wedges (100) and the strand (12) when the wedges (100) are installed to the strand (12).
The method of claim 9, wherein the wedge ring (101, 101'):
further comprises one or more hooks (115) adapted to elastically retain a radial space between the wedges (100) and the strand (12) to maintain the clearance fit; optionally, wherein, once installed to the anchor (10), the wedges (100) couple to the outer surface of the strand (12); and/or,

further comprises a gap adapted to allow the wedges (100) adjacent the gap to separate, allowing the wedges (100) to be installed to the strand (12) in a direction perpendicular to the longitudinal axis of the strand (12).
The wedge assembly of claim 1, wherein:
at least one wedge (100) includes a guide (111) formed therein, the guide (111) adapted to assist in the separation of the wedges (100) when the wedges (100) are installed to the strand (12) from the side of the strand (12); and

wherein the wedge ring (101, 101') gap is positioned proximate the guide such that the separation of the wedges (100) substantially elastically expands the wedge ring (101, 101').
The wedge assembly of claim 11, wherein:
the wedge ring (101, 101') is adapted to be coupled to the groove (103) in a direction substantially perpendicular to the longitudinal axis of the strand (12); and/or,

one wedge (100) proximate the gap includes a guide (111); and/or,

both wedges (100) proximate the gap include guides (111); and/or,

the guide (111) comprises one or more chamfers, ramps, curves, fillets, or combinations thereof.
The method of claim 6, wherein:
at least one wedge (100) includes a guide (111) formed therein, the guide (111) adapted to assist in the separation of the wedges (100) when the wedges (100) are installed to the strand (12) from the side of the strand (12); and

wherein the wedge ring (101, 101') gap is proximate the guide (111) such that the separation of the wedge ring (101, 101')s substantially elastically expands the wedge ring (101, 101');

aligning the wedge assembly with the guide (111) such that the guide (111) is aligned with the strand (12);

pressing the guide (111) against the strand (12) such that the wedges (100) are separated and the gap is expanded and the wedge ring (101, 101') expands elastically as the wedge ring (101, 101') is installed on the strand (12).
The method of claim 13, wherein:
one wedge (100) proximate the gap includes a guide (111); and/or,

both wedges (100) proximate the gap include guides (111); and/or,

the guide (111) comprises one or more chamfers, ramps, curves, fillets, or combinations thereof.