Abstract:
Anchor systems for joining structural members include a resiliently deformable member such as a dished washer to permit easy visual determination that the anchor system is correctly tightened in place. Post-tensioned anchor systems of the kind disclosed are particularly suitable for joining structural members, such as end-to-end columns. One of a number of mold parts, including a threaded tapered mold part, forms a threaded tapered hole in a poured concrete structural member for use with anchors, and passages permitting the introduction of a resinous securing agent may be formed in cooperation with the threaded tapered holes. Highway barriers can be formed with such holes and joined with the resin filling the holes and space between barrier ends.

Description:
This application is a continuation-in-part of application Ser. No. 08/388,526, filed on Feb. 14, 1995, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to anchor systems for joining structural members, methods of making and using those systems and combinations of structural parts joined by the anchor systems. More particularly, the invention relates to tensioned anchor systems that give an indication that the system is under the appropriate tension, mold parts used to adapt poured concrete structural members for use with the anchor systems and joined structural members, such as columns and road barriers, employing the anchoring systems of the invention. 
     Threaded anchors that are secured with a securing agent in a hole into which the anchor is inserted are well known. In an improved anchoring system a fast setting polymer resin is introduced into the hole to fill the bottom portion of the hole, and a significantly slower setting resin securing agent fills the remaining upper portion of the hole. Then, once the faster setting securing agent has set, the anchor is tensioned by turning down a retaining nut on the exterior end. The torque induced tension to which the anchor is drawn is calculated to be higher than any subsequent forces the anchor will subsequently receive when loaded. The tension is maintained in the anchor portion extending from the quick-setting securing agent to the nut as the slower setting securing agent hardens. The load transfer via the resins to the surrounding concrete structure is accomplished on a molecularly bonded radially distributed basis over the height of the now adhesively secured, strained steel anchor. The bonded, extended anchor thus has its torquing energy distributed to the concrete causing compression within the structure. The stored energy in these systems is available to react to subsequent loads. The molecular bonding provides much more efficient load transfer than a mere mechanical action from commonly used non-shrink cementitious grouts. 
     In the improved systems as just described it was not evident if subsequently the anchor had loosened, for example, by elongation due to creep. Nor was there a means for continuing to apply tension to an elongated anchor member. 
     Structural members such as columns supporting bridges or freeways have utilized adjoining openings between which extend an anchor member that may have been grouted in at least one of the openings, but that was itself passive or free of loading. During earthquakes, these joined structural members have been known to fail at such junctions. Typically the rebars joining the members are not pre-loaded, nor bonded to the concrete. Thus, they have very little capacity to resist enormous multi-directed lateral and vertical seismic forces. 
     A means for quickly readily forming a structural member to accept chemically secured-in-place anchors without leaving behind a residue of release agent in the freshly poured concrete has been needed to assure that a liquid securing agent introduced into a hole molded in the concrete had purchase on the interior surface of the hole and readily transfer loads on a molecular basis by virtue of the bond anchor and the concrete. Known hole firming devices have acted as bond breakers to the concrete. The result has been mechanical load transfer from the anchor to the concrete rather than load transfer at a molecular level. 
     Road barriers have been joined end-to-end in the past, but have not been readily adapted for the introduction of grout into anchor receiving openings, and they have not been joined end-to-end with an anchor especially adapted to permit their being situated at an angle other than 180°. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with this invention there is provided improved anchoring systems and their methods of use, whereby a deformable indicating member is located between a retaining member or nut and the surface into which the anchor protrudes. Upon tightening, the deformed member is resiliently deformed. However its elastic memory urges its return towards its previous, undeformed condition so that, should the anchoring system tend to loosen by virtue of elongation of the anchor, the tendency of the deformable member to return to its initial condition indicates this fact and continues to place the anchor in tension. 
     The use of a post-tensioned anchor system to join columns end-to-end by introduction of the anchor system into a diagonally formed hole opening through the side of one of the columns places the columns in compression at their adjoining faces unlike the passive anchors previously used and found to be vulnerable in earthquakes. The system is especially suitable for retro-fitting columns joined in the manner previously described. Because load transfer in these chemically secured anchors operate at the molecular level an extremely secure adherence of the anchor to the structural member is afforded, one that typically exceeds the tensile strength of the anchor. 
     In securing road barriers to road surfaces superior force resistance has been observed by use of a tensioning method similar to that mentioned above for joining columns. A hole in the road surface is filled or partially filled with a fast setting resinous cement or securing agent, and an anchor is introduced into the hole through an aligned hole in the barrier. After the fast setting cement has set, a slower setting grout or securing agent is introduced to fill or partially fill the aligned holes in the road surface and the barrier. Before the slower setting grout or securing agent sets, the anchor is tensioned as described above to bring the road surface and barrier into compression by turning down a nut on the protruding threaded end of the anchor. Again, a stored energy system is created that is very resistive to impact or other external forces. The dished washer can again serve as a visual indicator of the tensioned condition of the anchor. 
     Poured concrete structural elements such as columns, footings for lamp standards, and concrete highway barriers, to name just a few, need to have holes formed to receive hardening securing agent if a chemically secured-in-place anchor is to be used. These holes can be molded efficiently through the use of an inventive, tapered mold part threaded along its length and formed of a plastic that readily releases from the hardened concrete around it. The tapered or conical shape permits quick removal by just a few turns until the threads of the mold part are free of the threads it has formed in the concrete structural member, at which time the mold part and can be lifted out. The use of a rod-like mold part in communication with the tapered mold part readily defines passages from the exterior of the structural concrete member to the interior of the tapered, threaded hole formed by the tapered, threaded mold part. By that means liquid securing agent can be introduced through the passages left by the rod-like mold part. 
     Additional means for forming a hole for anchors subsequently to be bonded to the inside walls of the formed hole include: 
     1. a longitudinally slit non-adherent sheath or sleeve that covers a metal rod. Upon withdrawal of the rod, the sheath snaps inward to its relaxed condition and is easily withdrawn. 
     2. A hard mold part covered with a plastic or other chemically removed covering of sufficient thickness such that when the mold part is withdrawn following chemical destruction of the covering, there results an annular space between the mold part and the molded concrete structural member of sufficient width to permit the introduction of securing adjacent. The hard mold part may be the anchor itself. 
     3. A mold part covering of polystyrene foam or other material that is sufficiently resistive to compressive forces to withstand the unhardened concrete in which it is immersed, but that will crumble upon withdrawal of the mold part. 
     4. A plastic forming device particularly useful in elaborate molded passages and holes and filled with ice or another hardened material capable of being melted after the concrete structural member sets, whereupon easy withdrawal is effected. 
     Structural member combinations that are efficaciously formed by the anchoring systems of the invention include joined columns and joined road barriers. In the case of road barriers intended to be used on a curve, these can be brought end-to-end at less than 180°, so as to follow the curve, and between them, extending into the openings molded therein, a similarly bent anchor member, which may be a length of rebar, extends from within one of the holes in one of barriers to an aligned hole in the adjacent barrier. 
     The above and further advantages of the invention will be better understood from the following detailed description of a preferred embodiment taken in consideration with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view partly in section of a grout-in-place anchor system with a deformable load indicating washer; 
     FIG. 2 is a further side elevation view partly in section of the anchor system of FIG. 1 showing its anchor under tension and the washer deformed; 
     FIG. 3 is a fragmentary side elevation view of a typical installation suitable for use of the anchor system of FIGS. 1 and 2; 
     FIG. 4 is a fragmentary, partially sectional view of an anchor system like that of FIG. 1 installed to join columns abutting end-to-end; 
     FIG. 5 is a further fragmentary partially sectional view of a further embodiment of the installation of FIG. 4; 
     FIG. 6 is a fragmentary side elevation view partly in section and shows a tapered mold part and the hole formed thereby in a concrete structural member; 
     FIG. 7 is a side elevation view of an alternative embodiment of a tapered mold part; 
     FIG. 8 is a fragmentary perspective view of a system of mold parts to form a tapered hole and connecting passages in a cast concrete structural member; 
     FIG. 9 is a fragmentary sectional view of the cast concrete structural part formed with the mold part assemblage of FIG. 8; 
     FIGS.  10 - 13  are fragmentary side elevational views partly in section of further embodiments of mold parts suitable for use in making poured concrete structural members in accordance with the invention. 
     FIG. 14 is a fragmentary perspective view of poured concrete columns with holes and passages for the introduction of a liquid securing agent; 
     FIG. 15 is a fragmentary perspective view of a cast concrete road barrier with holes and passages; and 
     FIG. 16 is a fragmentary top plan view of a pair of barriers like that of FIG. 11 joined angularly by a pre-bent anchor member. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     In FIG. 1 an anchoring system  20  includes a threaded anchor  22  with a retaining nut  24  threaded thereon, a washer  25 , and a dished and resiliently deformable washer  27  such as a belleville washer. The anchor  22  which is an elongate threaded member extends into a hole  28  in a structural member  31 . The anchor  22  is shown extending through an opening in a plate  33 . 
     In FIG. 3, in a typical use of the anchoring system  20  of FIG. 1, the plate  33  is the mounting flange of a light standard, for example, which is secured to a footing which is the structural member  31 . A multitude of other, readily apparent uses of the anchoring system will be recognized. 
     In the hole  28 , the anchor system  20  includes a quantity of a fast-setting polymer resin or other securing agent  35 . This fills the bottom of the hole  28  in surrounding relation to the lower end of the anchor  22 . Above the quick-setting securing agent  35 , a quantity of slower-setting resin or securing agent  36  fills the remainder of the hole  28 . A typical fast-setting polymer resin suitable for use as the resin  35  of FIG. 1 is the product sold under the trademark Keligrout by Kelken Construction Systems of Princeton, N.J. The slower-setting resin may be one of the products sold under the trademark Kelipoxy or Keliresin by the same Kelken Construction Systems. 
     Once the quick-setting resin  35  has set, securing the immersed end of the anchor  22  at the bottom of the hole  28 , the retaining nut  24  is tightened down upon the deformable washer  27 , flattening the washer and placing the anchor  22  in known and readily discernible tension between the quick-setting resin and the retaining nut  24  as seen in FIG.  2 . The dished washer  27  provides a visible indication that the anchoring system  20  has been correctly tightened. The slower-setting resin  36  sets after the anchor has been thus-tensioned. This forms, in effect, a post-tensioned, bonded, pre-loaded system and causes the tension force that elongates the anchor to be stored as reserve energy, compressive forces in the concrete. 
     Should the anchor system  20  loosen, for example by elongation of the anchor  22  as a result of creep, or by loosening of the nut  24 , the deformed washer  27  will return towards its dished condition thanks to its elastic memory and this indicates the loosened condition of the system. The memory urging the dished washer  27  towards its undeformed, dished shape applies tension to the anchor  22  via the nut  24 , as well. 
     In FIG. 4 an anchor system  40 , similar to system  20  of FIG. 1, secures together a pair of end-to-end columns  41  and  42 . A slanted or diagonal hole  44  opens out of the side of the upper column  41  at an area  46  adapted to receive the washers  25  and  27  and a nut  45 . The hole  44  or an aligned hole proceeds diagonally to the interface  48  of the two columns and proceeds into the lower column  42 . 
     The portion of the hole  44  that is in the lower column  42  is filled with the quick-setting resin  35 . The portion of the hole  44  extending upward from the interface  48  to exit the side of the upper column  41  is filled with the slower-setting resin  36 . Again, the anchor  47 , here a length of threaded rebar, is tensioned between the nut  45  and the hardened quick-setting resin  35 . This places the columns  41  and  42  in compression at the interface  48 . 
     In similar fashion, other upper members such as road barriers may be secured to such lower members as road surface for an improved system capable of withstanding significant external forces. In such a case, the member  42  would be the surface of the road and the member  41  would be the barrier. The aligned holes in the lower and upper members would be diagonally formed if necessary or simply vertically formed depending on the dimensions and formation of the barrier. 
     In FIG. 5 an alternative column-connecting configuration differs from that of FIG. 4 only in its use of a shoe  49  that provides an engaging surface for the nut  45  at the side of the column  41 . By the tensioning of the anchor  47  to tightly compress together the adjoining faces of the columns, the anchoring arrangements of FIGS. 4 and 5 are intended to better withstand the upheaval of an earthquake. These anchoring configurations may be used to retrofit columns previously joined by, for example, passive anchors extending from the lower column, where they might be grouted in place, into the upper column, but without the post-tensioning effect. Failure of structures at such locations has been observed following earthquakes. 
     In FIG. 6 a mold part  52  has a tapered and threaded exterior surface  54 . Below it is shown a corresponding hole  58  formed by the mold part  52  in a poured concrete structural member  59 . Threads  61  formed in the hole interior surface facilitate the securing of resin in the hole when used with a system like that of FIG. 1, for example. The mold part  52  is made of high density polyethylene or any high strength material that has good release ability against the just-formed concrete. Alternatively the mold part  52  may be coated with such a plastic. Because it uses no lubricating release agent, no residual release agent remains in the hole  58  to interfere with the molecular bonding of the polymer resin to the interior of the formed hole capable of transferring the elastic load in the anchor to the concrete. 
     The taper of the mold part  52  also assists in the quick breaking away of that part from the freshly-formed hole. After a few turns, the part may be withdrawn upward as the threads on the external surface of part  52  will have cleared the threads on the internal surface of the hole  58 . 
     In FIG. 7 an alternative mold part is shown in which two generally conical tapered exterior surfaces  63  and  64  are shown joined at a step down in diameter  66 . Although the tapered surfaces of both of the mold parts  52  and  62  may be conical, as shown, other tapered shapes will suffice. Both mold parts are provided at their upper ends with a threaded projection  57  and  67 , respectively, having an opening through there and providing a means for grasping the part from above. 
     In FIG. 8 the tapered mold part  52  is shown in a system of mold parts. The system includes a cup-shaped part  71  that receives the tapered end of the mold part  52 . Rod-like parts  73  extend to the exterior of a mold, a portion of which is illustrated at  75 . 
     In FIG. 9 a poured concrete structural member  78  has internal openings formed by the system of mold parts of FIG. 8. A tapered hole  81  communicates with passages  82  and  83  through the retained cup-like part  71 . The passages  82  and  83  permit the introduction of resin even when the upper end of opening  81  is not accessible. Typically an anchor member will be introduced into the opening  81  and extend into the interior of the cup-like part  71 . In an alternative system of mold parts the tapered part  52  may be press fit directly into openings formed at preselected locations in rods or tubes like the parts  73 , eliminating the retained cup shaped parts  71 . 
     Additional means for forming holes to accommodate anchors and passages for the introduction of resin are shown in FIGS.  10 - 13 . 
     In FIG. 10, a hole in a structural member  86  is formed by a mold part that includes a core element  87  shown as a length of rebar and a longitudinally slotted sleeve  88 . Before the concrete member  86  is poured, the sleeve  88  is resiliently spread to fit over the end of the element  87  and located appropriately with respect to the mold for the structural member  86 . After the poured concrete has set, the core element  87  is withdrawn. The sleeve  88  contracts elastically to its original diameter and is readily withdrawn from the newly formed hole. To assure return of the sleeve  88  from its expanded condition, a suitable soft filler may be inserted in the slot  89  to prevent the entrance of the poured concrete, but allowing elastic return of the sleeve  88  to its original, reduced diameter. The FIG. 10 core element and sleeve may be used either to form the hole that is subsequently to receive an anchor, as shown, or in the same manner as the rod-like member  73  of FIG. 8, to form the resin introduction passages  82  and  83  of FIG.  9 . 
     In FIG. 11 a plastic sleeve  91  surrounds a core element  92  to form a molded hole in a structural element  93 . The plastic of the sleeve  91  is degradable by use of an appropriate, known solvent, indicated at  94 . Preferably the sleeve  91  is destroyed after removal of the core element  92 , but alternatively while the element  92  is in place, which element may be the anchor to be retained. 
     In FIG. 12 a hole in a structural element  96  is molded by a mold part that is a core element  98  and a sleeve  99  that may be polystyrene foam or another material of similar characteristics. The polystyrene foam  99  has sufficient resistance to compression to withstand the inward pressure of the poured concrete of the structural element  96 , but upon withdrawal of the core element  98 , the polystyrene of the sleeve crumbles. The crumbled sleeve is easily removed to leave a clean, dry hole. 
     A fourth alternative embodiment, shown in FIG. 13, utilizes thin, hollow plastic members  101  and  102  that are given their sufficient structural integrity by a hardened core material  104  such as ice. Melting of the core material  104  after formation of the structural element  106  enables easy withdrawal of the remaining plastic pieces  101  and  102 . 
     In FIG. 14 a typical installation is illustrated. Here two poured concrete structural members  110  and  111  meet at adjoining faces. Aligned holes  113  in the upper and lower structural members receive anchors extending between them (not shown in FIG.  14 ). Resin is introduced into the anchor-containing holes through passages  115  and the retained cup-like parts  116 . 
     A further arrangement utilizing molded interior holes and passages is shown in FIG. 15. A cast concrete road barrier  120  has internally threaded conical holes  121  formed therein. The holes  121  communicate with passages  124  through retained cup-like parts  123 . Into the holes  121  and the cup-like parts  123  extend anchor members  126  that are, in this case, sections of rebar. 
     A second barrier, not shown, similarly equipped with holes and passages is brought into alignment with the end of the barrier  120  to receive the free ends of the anchor members  126 . Resin introduced through an opening  127  of the passage  124  fills the cup-like mold parts  123  and the threaded holes  121  to secure the anchor members  126  and thus connect the barriers end-to-end. 
     In a further embodiment of the highway barrier system just described, as shown in FIG. 16, a pair of barriers  131  and  132 , are arranged end-to-end. To accommodate a curve in a highway, the barriers are arranged at an angle other than 180°. The anchor member  134  joining together the two barriers  131  and  132  is pre-bent accordingly to permit this relationship. The conical holes  121  allow the pre-bent anchor member to be placed at any attitude so as to accommodate a wide variety of angles between the joined barriers. A butyl rubber seal  135  closes one side of the space between the end faces of the barriers, and a compressed length of suitable compressible plastic or plastic foam  136  is forced into and seals the larger side of the intermediate space. Again the resin is introduced through openings  127  to fill the interior cups  123 , the threaded conical holes  121 , and the sealed space  139  formed between the ends of the barriers. 
     Although preferred embodiments of the invention have been described herein it will be recognized that further modifications and alterations may be made by those skilled in the art without departure from the spirit and scope of the invention as defined in the appended claims.