US3160988A - Stress-gradient anchor - Google Patents

Stress-gradient anchor Download PDF

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Publication number
US3160988A
US3160988A US76339A US7633960A US3160988A US 3160988 A US3160988 A US 3160988A US 76339 A US76339 A US 76339A US 7633960 A US7633960 A US 7633960A US 3160988 A US3160988 A US 3160988A
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United States
Prior art keywords
anchor
undulations
axis
concrete
coupling portion
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US76339A
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English (en)
Inventor
Chester I Williams
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Individual
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Individual
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Publication date
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Priority to US76339A priority Critical patent/US3160988A/en
Priority to GB10841/61A priority patent/GB955729A/en
Priority to DE19611434518 priority patent/DE1434518A1/de
Application granted granted Critical
Publication of US3160988A publication Critical patent/US3160988A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
    • E04G21/14—Conveying or assembling building elements
    • E04G21/142—Means in or on the elements for connecting same to handling apparatus
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/38—Connections for building structures in general
    • E04B1/41—Connecting devices specially adapted for embedding in concrete or masonry
    • E04B1/4114—Elements with sockets
    • E04B1/4121—Elements with sockets with internal threads or non-adjustable captive nuts
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/38—Connections for building structures in general
    • E04B1/41—Connecting devices specially adapted for embedding in concrete or masonry
    • E04B1/4157—Longitudinally-externally threaded elements extending from the concrete or masonry, e.g. anchoring bolt with embedded head
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G11/00—Forms, shutterings, or falsework for making walls, floors, ceilings, or roofs
    • E04G11/06—Forms, shutterings, or falsework for making walls, floors, ceilings, or roofs for walls, e.g. curved end panels for wall shutterings; filler elements for wall shutterings; shutterings for vertical ducts
    • E04G11/20—Movable forms; Movable forms for moulding cylindrical, conical or hyperbolical structures; Templates serving as forms for positioning blocks or the like
    • E04G11/28—Climbing forms, i.e. forms which are not in contact with the poured concrete during lifting from layer to layer and which are anchored in the hardened concrete

Definitions

  • the ability of theanchor to withstand stresses is also related to the behavior of the concrete itself. yIt is characteristic of concrete that it is weakest in tension, and it will therefore fail on planes at which the tensile stresses are at a maximum. In the case of embedded anchors,
  • Vthe outer end ⁇ of the anchor ispositioneda few inches from the surface of theconcrete, and the anchor extends from there to greater depth, it may be presumed that the grip of the concrete over the entire length of the anchor is required *to resist the forces involved. ⁇ The grip of the concrete-on the rst few inches of the an- ⁇ chor will therefore usually be inadequate to resist the total loading, since the anchor would pull out lthe surrounding concrete if all the resistance were centered there.
  • an anchor can create a very desirable stress gradient over its length, and a correspondingly unconcentrated load transfer to the concrete, if it is provided with a conformation having a series of undulations graduated in amplitude per unit of length of undulation. ThisV can be accomplished in several ways, among these being:
  • the concentrations of stress near the surface of the concrete can be climinated by providing a tangential relationship of the anchor with respect to the axis of pull at the-point of connection to the anchor.
  • This tends to be an application of the same principles outlined above, if the anchor is ⁇ provided with an arcuate or curved contiguration such that each point along the length of the anchor is progressively disposed at a greater angle with respect to the axis of pull.
  • An arcuate formation at a relatively constant radius, or a parabolic configuration (with the point of increased curvature at the inner end of the anchor) will satisfy this requirement.
  • This conguration may be used alone, or in combination with the graduated undulations referred to above. In the latter case, the continuous curvature is applied to the axis of the undulations; ⁇
  • FIGURE 1 presents a view in side elevation of an anchor formed in a parabolic curve, the anchor itself being of rod stockfwhich is corrugated by the provision of a rolled thread on its surface.
  • FIGURE 2 ⁇ presents a view in side elevation of a modified form of the invention ⁇ illustrating an anchor having a progressively increased amplitude of undulations and a substantially constant undulation period, or lengt vThe axis of the undulations is itself formed in a parabolic curve.
  • FIGURE 3 presents a modified form of the invention .in Whichjthe plane of theundulations is generally per-V pendicular to the plane of the parabolic curvature.
  • FIGURE 4 presents a modified form of the invention involving a progressively increased curvature of undulations.
  • FIGURE 5 presents an varcuate formation of the anchor shown-fin FIGURE 4, in side elevation.
  • FIGURE6 illustrates a furthermodification of the inventionyshowing undulations Vof substantially constant amplitude and progressively decreasing period.
  • FIGURE 7 illustrates a cluster of anchor rods secured to a connector.
  • FIGURE 8 illustrates the attachment of an eye itting for a single anchor rod.
  • the anchor illustrated in FIGURE 1 is essentially a piece of steel rod indicated at 10 with a threaded coupling portion at the outer end 11 emerging from a recess 12 shown in dotted lines in the concrete.
  • the threaded end 11 establishes the axis of pull on the anchor, the loading normally being applied to the anchor by a so-called she-bolt which secures the forms in place.
  • the surface of the rod may be corrugated, if desired, by an annularor helical pattern indicated at 13.
  • the axis of the rod 10 is formed substantially along the curvature of a parabola, with the maximum curvature existing at the inner end portion identified at 14. It will be noted that the curvature of the rod with respect to the axis of pull progressively increases with distance from the point of connection. Stated another way, the angle of a rod element to the axis of pull near the end 14 is greater than the angle of the axis of a rod element nearer the threaded end 11.
  • the anchor 15 is kinked or undulated in a plane approximately the same as the plane of the parabolic curvature of the neutral axis of the undulations.
  • the period (length) of each undulation is relatively constant over the length of the anchor so that the distance between the peaks shown at 16 is substantially the same as that shown at 17.
  • the amplitude ot the undulations progressively increases over the length of the rod from the outer threaded end to the inner end indicated at 18.
  • the amplitude of the undulations may be considered as the distance from the dotted lines 19 or 20 to an undulation axis disposed exactly between these lines.
  • the modification shown in FIGURE 3 is similar in general principle to that shown in FIGURE 2, except that the undulations are formed in a plane perpendicular to the plane of the parabola of the undulation axis. Tension is applied to the modiiication shown in FIGURE 3 at the threaded outer end 21, and the amplitude of the undulations of both the FIGURE 2 and FIGURE 3 modifications is the primary variable. In most cases, the amplitude of undulations may increase until the distance between the lines 19 and 20 is approximately one and one-half diameters of the rod of which the anchor xs made. In some instances, it may be desirable to increase this final amplitude, as is the case in FIGURE 3.
  • the graduated amplitude will normally not have to exceed the one and one-half diameter rule in order to adequately secure the rod in the concrete, and it will usually decrease the concentration of stresses in the concrete to adhere to this limitation.
  • the manufacture of the anchors will usually be easier with the arrangement shown in FIGURE 2, since the same bending operation which establishes the parabolic configuration can also be used to form the undulations; while in the FIGURE 3 mod1fication,it will normally require two bending operations.
  • the period of the undulations shown at 22 is substantially the same as that identified at 23.
  • the final end 24 and also the end 18 shown in FIGURE 2 be left of more or less indeterminate configuration, since the shape of this point is not excessively critical.
  • FIG- URE 2 and FIGURE 3 are essentially arcuate portions at the lateral extremities of the undulation, connected by relatively straight portions which are tangential to the curves. This arrangement is by no means critical, however, and the showing of FIGURES 4 and 6 will illustrate undulations in which no tangential portions are used, the curves leading directly into each other.
  • the anchor shown in FIGURES 4 and 5 has the threaded outer end 25, with the undulations 26, 27, 28, and 29.
  • the graduations in these undulations are in the degree of curvature, this degree progressively increasing to the right, as shown in FIGURE 4.
  • These undulations are formed by a decrease in the radii of curvature from that shown at 3f) to that indicated at 31.
  • the radii of the undulations 28 and 29 are the same.
  • the amplitude of the undulations has not been maintained constant.
  • FIGURE 5 illustrates the anchor shown in FIGURE 4 on a plane perpendicular to that of FIGURE 4, FIG- URES 4 and 5 being in projection.
  • the anchor 32 is formed in an arc of continuous curvature, the radius of curvature being indicated at 33. This curve is tangential to the axis of the threaded end-25, and it will be noted that the angle of the axis 34 of the undulations is disposed at a progressively increasing angle with respect to the axis 35 of the threaded end 25, over the length of the anchor.
  • the force applied to the anchor at the threaded cnd 36 of the modification shown in FIGURE 6 is transferred through the rod, and is resisted by the engagement of the undulations 37-41 with the surrounding concrete.
  • These undulations are formed with a progressively increasing curvature, as indicated by the decreasing length of the radii 42-47.
  • the amplitude of the undulations is maintained substantially constant throughout the length of the anchor shown inFIGURE 6, the line 48 down through the center of the vcross-section of the rod moving between the boundaries 49 and 50 which are equally displaced on opposite sides of .the axis of the threaded end 36.
  • the extreme inner end V51 may be left at a random configuration to simplify the bending operation, if desired.
  • the anchor shown in FIGURE 6 may be left with the axis of the undulations coincident with the axis of the threaded end 36, or it may be displaced in an arcuate, parabolic, or some other curved arrangement.
  • the curvature of the undulation axis is usually arranged to create a downward deviation, since the anchors are frequently embedded not only near a vertical face, but also near the top of the pour. This deviation permits the anchor to engage a deeper portion of the concrete than would be Ythe case if the undulaton axis were an extension of the axis of the threaded end.
  • FIGURE 7 illustrates an arrangement that is commonly used with other types of anchors where the forces to be 'transmitted at a given degree of set of the concrete ex- 5 ceed the holding power of a single rod.
  • This form of cluster anchor is adaptable to the type of rods discussed herein, and the undulated rods 52-54 are shown welded to the several turns of the helical coil S5 of steel rod which forms a thread ⁇ system for engagement with the threaded end 56 of the she-bolt 57.
  • FIGURE 8 shows an alternative form for the embedded end of an anchor.
  • the positioned anchors Prior to and during the pouring of the concrete, the positioned anchors present troublesome points on which to accidentally catch tools, equipment, and the clothing of Workmen. The possibility oi physical injury at these points is also present.
  • the end of the anchor 58 may be formed in an eye 59 to present a rounded contour.
  • An achor for engagement with poured concrete said anchor comprising: at least one rod member having'a threaded coupling portion and an engaging portion extending from said coupling portion, said engaging portion having undulations of increasing curvature proceeding from said coupling portion, said undulations being formed With respect to an axis having continuous curval ture and extending in tangential relationship to the axis of said coupling portion.
  • An anchor for engagement with poured concrete said anchor comprising: at least one rod member having a threaded coupling portion and an engaging portion extending from said coupling portion, said engaging portion having undulations of increasing ratio of amplitude to period proceeding fromvsaid coupling portion, said undulations being formed with respect to an axis having continuous curvature andv extending in tangential relationship to the Vaxis of said coupling portion.
  • An anchor for engagement with poured concrete said anchor comprising: at least one rod member having a threaded coupling portion and anengaging portion extending fromr saidcoupling portion, said engaging portion having undulations of increasing curvature proceeding from said coupling portion, said undulations being formed with respect to an axis extending in tangential relationship to ⁇ the axis of said coupling portion.
  • An anchor for engagement with poured concrete said anchor comprising: at least one rod member ⁇ having a threaded coupling portion and an engaging portion extending from said coupling portion, said engaging portion having undulations of increasing ratio of amplitude to period proceeding from said coupling portion, said undulations being formed with respect to an axis extending in tangential relationship to the axis of said coupling portion.
  • said anchor comprising: at least one rod member having yan end provided with coupling means and an engaging portion extending from said end, said engaging portion having undulations of decreasing period at constant amplitude proceeding from said coupling portion.
  • An anchor for engagement With cast material said anchor comprising: at least one rod member having an end provided with coupling means and an engaging portion extending from said end, said engaging portion having undulations ofdecreasing period proceeding from said coupling portion.
  • Anfanchor for engagement With cast material said anchor comprising: at least one rod member having an end provided with coupling means and an engaging portion extending from said end, said engaging portion having undulations of increasing ratio of amplitude to period proceeding from said coupling portion.
  • An anchor for engagement with east material said anchor comprising: at least one rod member having an endprovided with coupling means and an engaging portion extending from said end, said engaging portion having undulations of increasing curvature proceeding from said coupling portion.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Mechanical Engineering (AREA)
  • Joining Of Building Structures In Genera (AREA)
  • Reinforcement Elements For Buildings (AREA)
  • Management, Administration, Business Operations System, And Electronic Commerce (AREA)
US76339A 1960-12-16 1960-12-16 Stress-gradient anchor Expired - Lifetime US3160988A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US76339A US3160988A (en) 1960-12-16 1960-12-16 Stress-gradient anchor
GB10841/61A GB955729A (en) 1960-12-16 1961-03-24 Anchor for concrete
DE19611434518 DE1434518A1 (de) 1960-12-16 1961-03-27 Spannungsgradientanker

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US76339A US3160988A (en) 1960-12-16 1960-12-16 Stress-gradient anchor

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US3160988A true US3160988A (en) 1964-12-15

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DE (1) DE1434518A1 (de)
GB (1) GB955729A (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3513609A (en) * 1968-03-13 1970-05-26 Du Pont Tendons for post-tensioned concrete construction
US3653217A (en) * 1970-08-03 1972-04-04 Chester I Williams Rock bolt rod configuration
US3830461A (en) * 1972-10-31 1974-08-20 C Williams Inner tie rod for securing wall forms
FR2319752A1 (fr) * 1975-08-01 1977-02-25 Papke Harald Dispositif pour la fixation de charges dans des ouvrages en beton arme
US4065903A (en) * 1974-12-03 1978-01-03 National Research Development Corporation Fixation and/or support means
AU568845B2 (en) * 1983-04-07 1988-01-14 Firma Pfeifer Seil-Und Hebetechnik G.m.b.H. & Co. Anchor tie
US5190270A (en) * 1991-07-16 1993-03-02 Huston Jerry D Apparatus for erecting foundation reinforcing bars and the like
US5954455A (en) * 1996-01-11 1999-09-21 Jennmar Corporation Combination bolt system
US20120279145A1 (en) * 2008-02-12 2012-11-08 Case Verige Pty Ltd Anchor for lifting a concrete component
US20120328896A1 (en) * 2010-03-02 2012-12-27 Anil Krishna KAR Reinforcing bar and method for manufacturing the same
US20170247892A1 (en) * 2016-02-29 2017-08-31 Midwest Concrete Masonry and Supply, Inc. Lifting anchor for precast concrete structures
US10273805B2 (en) * 2016-01-21 2019-04-30 Graden Colby Spring suspension clip

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT71212B (de) * 1914-04-11 1916-02-25 Carl De Rochi Steinschraube.
FR834613A (fr) * 1937-07-29 1938-11-25 Boyer Metallurg Système d'ancrage amovible pour le support et le maintien des coffrages dans les constructions en béton armé et autres application
US2724165A (en) * 1955-11-22 williams
US2788652A (en) * 1952-02-07 1957-04-16 Richmond Screw Anchor Co Inc Concrete anchorages

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2724165A (en) * 1955-11-22 williams
AT71212B (de) * 1914-04-11 1916-02-25 Carl De Rochi Steinschraube.
FR834613A (fr) * 1937-07-29 1938-11-25 Boyer Metallurg Système d'ancrage amovible pour le support et le maintien des coffrages dans les constructions en béton armé et autres application
US2788652A (en) * 1952-02-07 1957-04-16 Richmond Screw Anchor Co Inc Concrete anchorages

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3513609A (en) * 1968-03-13 1970-05-26 Du Pont Tendons for post-tensioned concrete construction
US3653217A (en) * 1970-08-03 1972-04-04 Chester I Williams Rock bolt rod configuration
US3830461A (en) * 1972-10-31 1974-08-20 C Williams Inner tie rod for securing wall forms
US4065903A (en) * 1974-12-03 1978-01-03 National Research Development Corporation Fixation and/or support means
FR2319752A1 (fr) * 1975-08-01 1977-02-25 Papke Harald Dispositif pour la fixation de charges dans des ouvrages en beton arme
AU568845B2 (en) * 1983-04-07 1988-01-14 Firma Pfeifer Seil-Und Hebetechnik G.m.b.H. & Co. Anchor tie
US5190270A (en) * 1991-07-16 1993-03-02 Huston Jerry D Apparatus for erecting foundation reinforcing bars and the like
US5954455A (en) * 1996-01-11 1999-09-21 Jennmar Corporation Combination bolt system
US20120279145A1 (en) * 2008-02-12 2012-11-08 Case Verige Pty Ltd Anchor for lifting a concrete component
US9663960B2 (en) * 2008-02-12 2017-05-30 Pre-Form Systems Duo Anchor for lifting a concrete component
US20120328896A1 (en) * 2010-03-02 2012-12-27 Anil Krishna KAR Reinforcing bar and method for manufacturing the same
US10273805B2 (en) * 2016-01-21 2019-04-30 Graden Colby Spring suspension clip
US20170247892A1 (en) * 2016-02-29 2017-08-31 Midwest Concrete Masonry and Supply, Inc. Lifting anchor for precast concrete structures

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Publication number Publication date
DE1434518A1 (de) 1968-10-31
GB955729A (en) 1964-04-22

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