United States Patent [I91I11111 11111111 Ill lllll lllll lllll Ill11 1111111111 1111111111111111 Ill lllll Ill1

USOO539258OA[I 11 Patent Number: 5,392,580

Baumann 1451 Date of Patent: Feb. 28,1995

[761

WIP21r511[521

1581

1561

M O D U L A R R E I N F O R C E M E N T C A G E S F O RD U C T I L E C O N C R E T E F R A M E M E M B E R SAND METHOD OF FABRICATING ANDE R E C T I N G T H E S A M E

Inventor: Hams U. Baumann, 312 EmeraldBay, Laguna Beach, Calif. 92651

Appl. No.: 879,971Filed: May 6,1992

Int. Cl.6 .. . . . . . . . . . . ..“................................. E04C 5/00U.S. Cl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52/660; 52/646;

52/653.1; 52/649.1Field of Search . . . . . . . . . . . . . .52/250, 251, 252, 653.1,

52/653.2, 253, 414, 677, 649.1, 649.2, 649.3,660-665, 686, 646; 211/151, 70.4; 256/l

References Cited

U.S. PATENT DOCUMENTS865,336 9/1907

1,389,942 9/19211,512,763 lo/19241,748,843 2/19301,911,018 5/19332,766,016 lo/19562,815,656 12/19573,003,290 lo/19613,221,463 12/19653,238,684 3/19663,245,189 4/19663,269,557 8/19663,331,179 7/19673,378,981 4/19683,473,285 lo/19693,604,180 9/19713,611,665 lo/19713,744,207 7/19733,916,592 11/19754,280,310 7/19814,409,764 lo/19834,454,702 6/19844,838,726 6/1989

Gardner ................................ 52/253Freyssinet ............................. 52/662Holmgren ............................. 52/660Kuckel ................................ 211/151Goeltz ................................... 52/646Miller et al. ............................ 256/lKlein et al. ............................. 72/16Lemer ................................... 50/407Schoch .................................. 52/665Wood .................................... 52/481Reiland .............................. 52/649.2Wahl ................................... 211/151Ernst et al. ........................... 52/686Home ................................... 52/677Reiland .............................. 52/649.3Wood .................................... 52/653O’Brien ................................. 52/723Oroschakoff ......................... 52/664Morohashi et al. ................... 52/252Tolliver ................................ 52/646Wilnau ............................... 52/127.3Bonilla-Lugo et al. .............. 52/745Lucas Huerta ..................... 403/397

FOREIGN PATENT DOCUMENTS3-90760 4/1991 Japan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52/721

OTHER PUBLICATIONS“Building Code Requirements For Reinforced Con-

crete etc.” by AC1 Committee 31%Standard BuildingCode, Nov. 1989, pp. 309, 311-314, 319-321.“Notes on AC13 18-83 Building Code Requirements forReinforced Concrete” pp. 30-12, 30-14, 30-20, 30-30,30-35, 30-36, 30-93.“Earthquake Design of Concrete Masonry Buildings”:vol. 1: Response Spectra Analysis and General Earth-quake Modeling Considerations, by Robert E. En-glekirk et al, Shear Wall Response Using Inelastic Re-sponse Spectra-pp. 9 l- 1 0 5 .“Lessons Learned from Recent Earthquakes and Re-search and Implications for Earthquake-Resistant De-sign of Building Structures in the United States”, Earth-quake Spectra, vol. 2, No. 4, 1986, pp. 825-826, 853,856.“Earthquake-Resistant Design”, Section 3, by N. M.Newmark et al., pp. 3-l through 3-27.Uniform Building Code, 1988 Edition, 2624-2625, pp,492-501.

Primary Examiner-James L. Ridgill, Jr.Attorney, Agent, or Firm-Stetina Brunda & Buyan

1571 A B S T R A C T

A generally rectangular wire grid of welded construc-tion is utilized to define and maintain the positioning ofrebar charged therethrough during the formation ofstructural column and girder cages. Pre-positioned tiesguide the rebar through the grid. The pre-positionedties are then tightened such that the rebar is held firmlyin place at the close tolerance positions defmed by theprefabricated grid. A plurality of such grids are assem-bled into expandable bundles such that they may beexpanded in an accordion-like fashion about rebarcharged therethrough, resulting in properly spacedgrids for defining and maintaining the position of therebar. Additional rebar members may then be chargedtherethrough to complete the construction of a columnor girder cage. The modular reinforcement cages of thepresent invention thus eliminate piecemeal engineeringrequirements by providing modular building conceptsin which a unique rebar bundle pattern facilitates im-proved containment.

18 Claims, 7 Drawing Sheets

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31

MODULAR REINFORCEMENT CAGES FORDUCTILE CONCRETE FRAME MEMBERS ANDMETHOD OF FABRICATING AN’D ERECTING

THE SAME

FIELD OF THE INVENTIONThe present invention relates generally to building

construction and more particularly to a ductile rein-forced concrete frame comprising prefabricated weldedgrids for defining and maintaining the position of rebar. . 1.. .

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charged therethrough sucn that high tolerances aremaintained, metal usage is minimized, and improvedstructural strength is obtained. Ductility is improved, 15thereby reducing the amount of earthquake resistingmaterial required by reducing the seismic forces that thestructure must resist. The present invention thus pro-vides a unique rebar bundle pattern for improved con-finement. Modular building concepts eliminate piece- 2.meal engineering requirements.

BACKGROUND OF THE INVENTIONFrames comprised of reinforced concrete columns

and girders for constructing buildings are well known. 25Such contemporary columns and girders are commonlyconstructed by first forming a latticework of rebar, i.e.,a cage, which reinforces and contains the concrete. Thecage, generally defining the column or girder, is sur-rounded by a form, commonly constructed of steel or 3.fiberglass. Concrete is then poured into the form suchthat the cage is encapsulated thereby. The concrete isthen typically vibrated to remove any voids formedtherein. The form may be constructed in place such thatthe resulting column or girder need not be moved after 35the concrete cures. Alternatively, the form may beconstructed at a convenient location, and the column orgirder thus fabricated subsequently moved to its finallocation.

In multi-level commercial buildings, the steel lattice- 40works or cages for such columns and girders are com-monly constructed by first disposing a plurality of elon-gate members or rebar upon a series of supports orhorses and then positioning a plurality of sections ofsmaller diameter rebar or wire formed into generally 45rectangular hoops about the larger elongate rebar mem-bers to generally define the desired cage. Further elon-gate members may then be charged through these rect-angular hoops and secured in position via wire ties.

As can be appreciated, this process is extremely labor 50intensive. Additionally, very loose tolerances, typicallyapproximately 4 inch, are maintained due to the difficultnature of handling and aligning such materials. Thus,the lateral position of an elongate rebar member at theintersection of one rectangular hoop may vary by as 55much as 1 inch relative to its position at the intersectionof another rectangular hoop. Such large tolerances arenot desired. They are tolerated by building codes be-cause of the present-day method of preforming thehoops and hooked cross-ties. 6 0

Typically such columns and girders are formed inthirty foot lengths, which are commonly required inbuilding construction. Splice bars are shorter lengths,typically approximately sixteen feet, of rebar which arewire tied to the abutting ends of adjacent columns such 65that they may be joined thereby. As can be appreciated,such splicing greatly increases material usage, weight,and cost as well as requires substantial labor in the prac-

tice thereof. Column bars are spliced by overlappingtheir offset ends. Girder bars are usually just capped.

The need for frame structures to exhibit a compara-tively high degree of ductility is particularly importantin geographic locations known to experience substantialseismic activity. In such geographic locations it is notuncommon for frame structures to experience sufficientforce to cause crushing or brittle failure of the concreteduring seismic activity. Such crushing or brittle failuremay result in catastrophic failure of the structural mem-ber.

For example, a portion of the encapsulating concretemay break away as a result of seismic activity. Thebreaking away of such a portion of the encapsulatingconcrete may then expose a portion of the rebar lattice-work or cage, allowing it to degrade from environmen-tal factors, i.e. moisture, smog, etc., and also allowing itto move outward due to the lack of a retaining effectprovided by the encapsulating concrete.

Furthermore, rectangular hoops are subject to rup-ture or breakage upon experiencing substantial seismicforces. Such substantial seismic forces may urge therebar restrained by the rectangular hoop outward withsufficient force to pull apart the bent ends of the rectan-gular hoop. Columns using cross-ties with 90-degreebends, when subjected to bending and axial forces, haveexhibited brittle failures caused by the 90-degree bendsstraightening out. Also intermediate longitudinal barsbetween cross-ties buckle outward due to lack of posi-tive confinement, thus causing a brittle failure of theconcrete. Thus, such construction is inadequate for usein geographic locations known to experience substantialseismic activity.

The prior art construction methods are thus laborintensive, require excessively large tolerances, utilize90-degree bends which are failure prone, and addition-ally utilize intermediate bars which tend to buckle pre-maturely.

As such, although the prior art has recognized, to alimited extent, the problem of fabricating structuralmembers such as columns and girders in a mannerwhich will withstand substantial seismic forces, theproposed solutions have to date been in effective inproviding a satisfactory remedy.

SUMMARY OF THE INVENTIONThe present invention specifically addresses and alle-

viates the above mentioned deficiencies associated inthe prior art. More particularly, the present inventioncomprises dimensionally stable structural frames utiliz-ing generally rectangular wire frames or grids, prefera-bly of welded construction, to replace the prier arthoops and to define and accurately maintain the posi-tioning of rebar members charged therethrough. Pre-positioned ties guide the rebar through each grid. Thepre-positioned ties are then tightened such that therebar is held firmly in place at the close tolerance posi-tions defined by the prefabricated grid.

A plurality of such grids may optically be assembledinto laterally expandable cages or grid bundles such thatthey may be expanded in an accordion like fashionabout rebar members charged therethrough. Positionerdevices, preferably wire loops, define the relative posi-tions of the grids once the bundle is expanded. Thisresults in properly spaced grids for defining and main-taining the position of the rebar in the finished cages.Additional rebar members may then be chargedthrough the grid bundles prior to expansion thereof to

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complete the construction of a column or girder cage.Such rebar members are attached to the grids via ties,

modules and/or the grids of columns or girders during

preferably formed of wire. The cage is disposed withinthe fabrication process, prior to the completion of weld-

a form and the form is then filled with concrete to com-ing. Snap-on split-sleeve rollers may be attached at any

plete the fabrication of a column or girder.time. Both spool-type and snap-on split-sleeve rollers

Bundles of grids with positioner devices attached can5 are preferably fabricated of steel. However, those

alternatively be expanded first and then have longitudi-skilled in the art will recognize that various other mate-

nal rebar members charged therethrough, instead ofrials, i.e., plastic, are likewise suitable.

being charged first and then expanded as describedThe split-ring snap-on rollers may be conveniently

attached to the grids of columns and girders when andabove. As a further alternative, only key, i.e., two upper 10 where required. Split-rings snap-on rollers are config-comer, rebar members are charged through the bundlefirst. Subsequently, the bundle is expanded and then the

ured as a generally cylindrical sleeves having a split

remaining bars are charged therethrough.formed longitudinally therein such that the sleeve may

The grids are of integral construction such that theybe pried open by manually enlarging the split therein.

need not be assembled at the job site. Thus, each of the 15This allows the sleeve to be positioned upon a wire

individual members of the grid are permanently inter-member or the like and the sleeve then closed by bend-

connected, i.e., by welding, to one another such thating the split shut.

interconnection need not be performed by constructionUse of the spool-type rollers and split-ring snap-on

personnel. Those skilled in the art will recognize thatrollers in various combinations are contemplated. Forexample, the spool-type rollers may be used at intervals

various other means of forming such integral grids are 20 along a column or girder to maintain alignment of thelikewise suitable. For example, integral grids can beformed by forging, molding, machining, the use of bolts

rebar charged therethrough during the charging pro-

or other fasteners, etc.cess while split-sleeve snap-on rollers are used interme-

For certain special applications such as reinforceddiate adjacent spool-type rollers to reduce friction and

columns using high strength concrete, the grids are 25thereby further improve the charging process.

made of prewelded elongated hoops of paperclip-likeThreaded couplings may optionally be used to attach

configuration positioned at go-degree orientation to oneadjacent columns and/or girders. The threaded cou-

another. Longitudinal reinforcement is chargedplings are initially threaded completely onto threaded

through the ends of these hoops. Grids or hoops couldportions of rebar extending from a first structural mem-ber. The threaded portions of rebar of the first struc-

be made of other materials, such as graphite pultrusion, 30 tural member are then aligned with correspondingetc.

The use of such prefabricated grids eliminates a sub-threaded portions of rebar of a second structural mem-

stantial portion of the labor required in the fabricationber such that the threaded portions of rebar abut. The

of structural members such as columns and girders uti-threaded couplings are then twisted such that theythread onto the threaded studs of the second structural

lized in the construction of building frames. Addition- 35 member. When the threaded couplings are positionedally, the high tolerances, typically within approximatelyl/16 inch, afforded by the use of such prefabricated

such that they envelope approximately equal portions

grids substantially enhances the structural strength andof the threaded studs of both structural members, at-

ductility of the building frames fabricated therewith andtachment is complete.

A substantial savings in weight is realized in the prac-additionally reduces the quantity of material required 40 tice of the present invention because the use of thefor such fabrication. Vastly improved ductility reducesthe amount of material required to resist earthquake

prefabricated grids eliminates a substantial portion of

forces in the entire building structure.the rectangular hoops utilized in the prior art construc-

Interconnection modules facilitate the convenienttion of the steel latticework. The ends of the hoops,which are typically bent inwards about a rebar member,

attachment of girders to columns to allow rapid charg- 45 are not present in the grids of the present invention.ing of splice bars through the girder and column cages.A ledge formed along the lower surface of the intercon-

Because of the large number of such rectangular hoops

nection module provides vertical alignment of the cageutilized in the construction of any given structural

attached thereto and supports the cage during the at-member, this savings is substantial. Additionally, thewelded construction of the grids reduces the number of

tachment process. Alignment members facilitate hori- 50 wire ties required. Additionally, the use of high strengthzontal alignment of the cage by providing an easilyobservable indication of horizontal alignment. Thus, the

wire ties for reinforcing the column and girder grids

girder cage or precast girder need merely be placedresults in a substantial weight reduction.

upon the ledge of the intercomrection module and posi-Strength and ductility is improved since every rebar

member is confined within a welded comer or weldedtioned in alignment with the alignment members to 55 T intersection of a grid when the cages are formed.facilitate correct alignment thereof, greatly reducingthe amount of labor involved in the attachment process.

There are no non-welded or weak comers in the present

Rollers positioned upon the interconnection moduleinvention which are particularly subject to failure dur-

and/or the prefabricated grids of the column cage oring seismic activity.

Because of the accuracy with which the steel rein-girder cage facilitate charging thereof. Such rollers 60 forcing lattices of the present invention are formed,both act as guides for charging and also substantiallyreduce the amount of work required by allowing the

they do not tend to distort or corkscrew as they are

rebar thus charged to roll thereover, thus reducingbeing erected. Such distortion or corkscrewing repre-

friction.sents a substantial problem in the prior art. It makes thefabrication and handling processes substantially more

Two types of rollers are disclosed. A fast or spool- 65 difficult and prevents uniform construction of the struc-type of roller comprises partitions for separating andproperly positioning two or more rebar members.

tural members. The resulting rigidity and high tolerance

Spool-type rollers are attachable to the interconnectionconstruction of the steel latticeworks of the presentinvention therefore substantially enhance and improve

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the erection process. Thus, the erection process requiressubstantially less time and is consequently less costly.

The prior art, using structural steel columns, is at adisadvantage because the structural steel columns resistearthquake forces in only one direction. Also, steelanide flange columns have a weak axis which reducestheir ability to support gravity loads. The present inven-tion, on the other hand, allows for the maximum num-ber of principal reinforcement bars to be arranged nearthe four outside edges of the concrete column wherethey will be efficiently resisting both axial gravity andbending moments, caused by lateral forces in both or-thogonal directions. At the same time the present inven-tion allows the girder bars to pass through the columnin a modular configuration.

By using bundled bars in both the column cage andthe girder cage, the present invention provides a modu-lar way to arrange reinforcement bars so that they canpass each other very efficiently in a four-way column-girder joint.

At the same time the rebar arrangement provides forconfinement of every rebar member, which is not thecase in the prior art.

This positive confinement of every column andgirder rebar member is achieved and the closely spacedorthogonally oriented high strength wires in the col-umn and girder grids are ideally positioned to resist thebursting forces created in the joint which cause brittlefailures of reinforced concrete joints.

The configuration of the present invention providesfor the equivalent of an external hydrostatic pressure ofseveral thousand psi. This new pattern of intersectingvertical and horizontal bars confined with orthogonallyoriented high strength wires at very close spacing cre-ates a new type ofconcrete frame which will allow thesafe use of reinforced concrete in much taller buildingsin seismic zones. At the same time, by automating thefabrication and erection of these highly ductile concreteframes, the cost of these tall buildings will be substan-tially less while their resistance to earthquakes will besubstantially greater. This new pattern of reinforcementand confinement thus allows much stronger frames tobe constructed whose members are significantly smallerin dimension.

Thus, for taller buildings, less rentable space is lost tocolumns and girders in the present invention. In addi-tion, because of the vastly increased ductility of thisnew kind of concrete frame, much less principal rein-forcing steel and concrete in both columns and girdersis required. This, in turn, reduces the dead weight of thebuilding which further reduces the lateral earthquakeforces and gravity loads.

Thus, the present invention has a three-fold advan-tage over prior art in both concrete and structural steel.The first is that rebar pattern allows for more reinforce-ment in smaller members. The second is that verticaland horizontal rebar members pass through the joint inan efficient modular way which makes erection muchfaster. The third is that the present column rebar patternallows the column to resist lateral forces from bothorthogonal directions, while at the same time resistingaxial forces more efficiently even though it is smaller.

These standard modular columns and girder cagesare all predesigned to tit together without interferencewhile erecting. Also these standard modular columnsand girders will best tested so that each has a knownductility ratio and known capacity.

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6During computerized analysis and design, the stan-

dard modular girder cage and column cage pattern isselected for each member based on its previously testedultimate capacity. Computerized shop drawings, in-cluding bill of materials, may be prepared using thestandard modular patterns of intersecting girder andcolumn reinforcement and of the adjustable forms. Acomplete computerized material take-off and labor orequipment estimate can then be prepared using the in-formation generated during preparation of the shopdrawings.

Computerized fabrication of the grids and principalreinforcement with ends offset can be accomplished.Computerized fabrication or joint cubes and grid bun-dles can then be performed as the final operation in theshop. In the field or in the shop, a computerized cageassembly machine can assemble the cages.

The modular reinforcement cages for ductile con-crete frame member of the present invention thus pro-vide a unique rebar bundle pattern for improved con-finement. This results in structural members which areless susceptible to the forces generated by earthquakes.

A building structure utilizing the present inventioncan be safely designed and constructed with approxi-mately half the amount of earthquake resisting materialthan is required in the prior art, which does not have theability to have the core concrete strained without battlefailure.

Furthermore, the improved dimensional toleranceand standardized construction techniques facilitated bythe present invention lend the structural membersformed thereby to the use of automation, i.e. robotics.Thus, the present invention both represents a substantialadvance in the art and facilitates such further advances.

These, as well as other advantages of the presentinvention will be more apparent from the followingdescription and drawings. It is understood that changesin the specific structure shown and described may bemade within the scope of the claims without departingfrom the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGSFIG. la is a plan view of a rectangular hoop utilized

in prior art column and girder fabrication;FIG. lb is a plan view of two of the rectangular

hoops of FIG. la having ten rebar members chargedtherethrough according to the prior art,

FIG. 2 is a perspective view of a welded grid havingpre-positioned ties formed thereon for use in the fabrica-tion of reinforced concrete columns according to thepresent invention;

FIG. 3 is a perspective view of a welded grid havingpre-positioned ties formed thereon for use in the fabrica-tion of reinforced concrete girders according to thepresent invention;

FIG. 3a is an enlarged perspective view showing theintersection of two rebar members representative ofthose of FIGS. 2 or 3 and illustrating the positioning ofa wire tie formed thereon;

FIG. 4 is a perspective view of an interconnectionmodule for interconnecting a plurality of girders and/orcolumns according to the present invention;

FIG. 4a is an enlarged view of three representativeintersecting rebar members of FIG. 4, illustrating thewelded construction of the positioner wire;

FIG. 5 is a perspective view of a collapsed expand-able cage or grid bundle constructed of the grids ofFIG. 2 interconnected via loops such that the bundle

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8may be expanded so as to properly position the rectan-gular grids relative to one another;

to be encompassed within the spirit and scope of theinvention.

FIG. 5a is an enlarged view of the comer portion oftwo of the rectangular grids of FIG. 5 illustrating the

The ductile frame of the present invention is illus-

expansion thereof;trated in FIGS. 2-19 which depict a presently preferred

FIG. 6 is a perspective view of a horse supporting5 embodiment of the invention. FIGS. la and lb depict

four rebar members;devices utilized according to prior art construction

FIG. 6a is an enlarged perspective view showing themethodology.

adjustable interconnection of two members of the horseReferring now to FIG. la, a prior art rectangular

of FIG. 6;hoop 10 is formed from a section of rebar such that it

FIG. 6b is an enlarged perspective view of a grid10 has four sides 12, 14,16, and 18, and is generally config-

bundle support of FIG. 8;ured as a rectangle. The rectangular hoop has comers

FIG. 7 is a perspective view of the overall column22,24,26, and 28. The ends 20 and 21 of sides 12 and 18,

fabrication process showing two sections of rebar heldrespectively, are bent inward such that they may be

in position by a plurality of horses, the rebar sections l5disposed about either side of a rebar member (31 in FIG.

having expandable cages or rebar bundles and intercon-lb) charged through the rectangular hoop 10 and posi-tioned at the comer 22 thereof.

nection modules depending therefrom;FIG. 8 is an elevational side view of the column fabri-

Referring now to FIG. lb, the prior art construction

cation process of FIG. 7 additionally illustrating theof a column or girder cage is illustrated. Two rectangu-

charging process;lar hoops 10 are disposed about ten rebar members 11,

FIG. 9 is an enlarged perspective view of an intercon-2o 30, and 31 such that the rebar members 11, 30, and 31

nection module of FIG. 7 having rebar membersare captured and contained within the rectangular

charged therethrough as in the fabrication of a columnhoops 10. As is well known to those skilled in the art, aplurality of such rectangular hoops 10 charged with

cage;FIG. 10 is a perspective view of a partially formed 25

rebar members 11,30, and 31 thus form a latticework or

girder cage according to the present invention;cage about which concrete is poured to form the de-sired structural member. Intermediate rebar members

FIG. 11 is an enlarged perspective view of one end ofthe girder cage of FIG. 10 illustrating splice bars ready

11 are not confined at a comer and are consequently

to charge horizontally through the column cage;more subject to moving due to this lack of containment

FIG. 12 is an enlarged portion of the end of the girder3. than are rebar members 30 and 31.

cage of FIG. 11 better illustrating the spool-type rollers;Referring now to FIG. 2, a generally square column

FIG. 13 is an elevational end view of the girder cagegrid 40 of the present invention is illustrated. The col-

of FIG. 11;umn grid 40 comprises a plurality, i .e. four, of first or

FIG. 14 is a perspective view of a column cage beinglongitudinal wire members 42 disposed perpendicularly

lifted by a crane into its final position;35 to a like plurality of second or transverse wire members

FIG. 15 is a perspective view of a plurality of column44 such that intersections 66, preferably welded joints,are formed. The first 42 and second 44 wire members

cages and girder cages attached together via intercon-nection modules to define a portion of a ductile frame

thus generally define a square. That is, the longitudinal

for a building;42 and transverse 44 wire members form plural orthog-

FIG. 16 is a top plan view of an interconnection4o onal cells. The total area of the grid 40 is approximately

module attaching four girder cages to a column accord-equal to, i .e., slightly less than, the cross-sectional area

ing to the present invention;of the structural member, i.e. girder, to be fabricatedtherefrom.

FIG. 17 is an elevational side view of the column,girders, and interconnection module of FIG. 16;

Disposed at a substantial number, preferably all, of

FIG. 17a is an enlarged perspective view of a split-45 the interior comers formed by the intersections 66 of

sleeve snap-on roller for facilitating charging of thethe longitudinal 42 and transverse 44 wire members are

columns, girders, or interconnection module with rebar;pre-positioned ties 46, preferably formed of wire. Those

FIG. 18 is a perspective view illustrating the use of askilled in the art will recognize that other materials, i.e.plastic, string, cord, tie wraps, perforated plastic ties,

threaded coupling to interconnect a precast concrete 50 etc., are likewise suitable. During the charging processcolumn and a precast concrete girder utilizing the cagesof the present invention; and

these pre-positioned ties 46 define apertures through

FIG. 19 illustrates the use of a plurality of threadedwhich rebar members are charged. After the charging

couplings to interconnect a column and a girder.process, these ties 46 firmly secure the charged rebarmembers in place.

DETAILED DESCRIPTION OF THE 55

PREFERRED EMBODIMENTThe detailed description set forth below in connec-

tion with the appended drawings is intended as a de-scription of the presently preferred embodiment of the 60invention, and is not intended to represent the only formin which the present invention may be constructed orutilized. The description sets forth the functions andsequence of steps for constructing and operating theinvention in connection with the illustrated embodi- 65ment. It is to be understood, however, that the same orequivalent functions and sequences may be accom-plished by different embodiments that are also intended

Each pre-positioned tie 46 is firmly attached at oneend thereof to a wire member 44 or 42. Those skilled inthe art will recognize that various means, e.g. welding,hot glue, etc., are suitable for attaching the ties 46 to thewire members 42 and 44. The other end of each tie 46 isdisposed proximate an intersecting wire member 42 or44 such that after charging, the wire tie may be tight-ened about the captured rebar member.

The use of such ties 46 with a prefabricated grid 40make possible high tolerances, i.e., approximately l/16inch, in the positioning of the rebar members chargedtherethrough. Such close tolerance positioning of therebar charged through the grids 40 minimizes metalusage, improves structural strength, and reduces the

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amount of time and labor required to form the structuralmembers.

The uniformly constant confinement provided by thepresent invention’s tight tolerance fabrication gives thereinforced concrete member much greater ductilitythan is present in the prior art. These consistently exactdimensions improve the reliability of the reinforcedconcrete structure and permit it to withstand violentearthquake forces.

The more exact dimensions of the grids of the presentinvention provide for the use of automated fabricationand assembly methods. They thus reduce the time re-quired for erection, as well as for the connection of thecages and precast members of the present invention.

The increase ductility of the structural members ofthe present invention makes them more resistant tolateral seismic forces. Thus, the members can be con-structed utilizing significantly less concrete and steelwhile maintaining the same earthquake resistance.

Referring now to FIG. 3, a generally rectangular grid60 for use in the formation of girders 130 (best shown isFIGS. 10 and 15) of the present invention is illustrated.The girder grid 60 comprises a plurality, i.e., three, firstor vertical wire members 62 disposed perpendicularlyto a plurality, i.e., four, of second or horizontal mem-bers 64. As in the column grids 40, pre-positioned wireties 46 are formed at the interior comers of intersectingwire members 62 and 64 and provide like benefits.

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Referring now to FIG. 3a, the intersection 66 of twowire members 62 and 64 having a pre-positioned tie 46attached thereto is illustrated. A weld joint preferablyinterconnects the two wire members 62 and 64. Suchwelded construction is preferably utilized in both thecolumn grids 40 of FIG. 2 and the girder grids 60 ofFIG. 3, because of the high strength union formedthereby. Alternatively, the column 40 and girder 60grids may be formed by molding, machining, utilizingfasteners, or forging. Those skilled in the art will recog-nize that various other materials and methods of form-ing prefabricated integral, one-piece, grids are likewisesuitable.

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40

An assembly fixture is utilized to hold the longitudi-nal 42 and transverse 46 wire members of the columngrid 40 or the vertical members 62 and horizontal mem-bers 64 of the girder grid 60 in position while the wiremembers 42 and 46 or 62 and 64 are interconnectedand/or the ties 46 are attached thereto.

A substantial savings in weight is realized in the prac-tice of the present invention because use of the prefabri-cated column 40 and girder 60 grids eliminates the ends20 and 21 of the rectangular hoops 10 (as shown inFIGS. 1 and 2) which are present in the prior art. Be-cause of the large number of such rectangular hoops 10utilized in the construction of any given structuralmember, this savings is indeed substantial. Labor is alsosaved by reducing the number of pieces that the workermust install.

4 5

5 0

55

The elimination of the ends 20 and 21 of the prior art_ .rectangular hoops 10 facilitates passage of the wet con- 60Crete through the grids of the present invention. It alsoenhances the vibration process such that voids are bet-ter eliminated in the present invention. Thus, concreteflow is improved and the integrity of the structuralmember is enhanced. More rebar can be used in smaller 65members without inhibiting the pouring and vibratingof the wet concrete. Thus, smaller members havegreater weight bearing capacity.

10Strength is improved since every rebar member is

confined within a welded corner or welded T intersec-tion of the grid. There is no non-welded or weak comerwhich is particularly subject to failure during seismicactivity.

Because of the accuracy and rigidity with which thesteel reinforcing lattices or cages of the present inven-tion are formed, they do not tend to distort or cork-screw as they are being erected. The resulting rigidityand high tolerance construction of the steel cages there-fore substantially enhances and improves the erectionprocess. Thus, the erection process requires less timeand is consequently less costly.

Referring now to FIG. 4, an interconnection module80 is illustrated. The interconnection module 80 com-prises a plurality of first 82 and second 84 perpendicu-larly intersecting horizontal wire members, preferablydefining prefabricated grids. The intersecting first 82and second 84 wire members define a plurality of sepa-rate planes which are interconnected via a plurality ofthird or vertical members 86. Three alignment members88 are preferably positioned vertically upon each verti-cal face of the interconnection module 80 to define theposition at which a girder is attachable. An anglebracket 90 having upper 92 and lower 94 perpendicularedges is attached at the lowermost portion of each ofthe four vertical faces of the intersection module 80 tofacilitate abutting attachment of girders thereto. Adja-cent angle brackets, i.e., those on adjacent faces of theinterconnection module are preferably formed at differ-ent heights or offsets relative to one another. Theseoffsets prevent the rebar members of perpendicularlyintersecting girders from interfering with each other.

Thus, a girder cage 130 (FIG. 10) may be attached toa column cage 150 (FIG. 9) having an intersection mod-ule 80 formed thereon by positioning one edge of thegirder cage 130 upon the lower edge 94 of the anglebracket 90 and aligning the girder cage 130 with thealignment members 88. Alignment of the vertical wiremembers 62 of the girder cage 130 with the verticalalignment members 88 of the interconnection module 80is thus attained. Ties may then be utilized to connect thegirder cage 130 to the interconnection module 80. Theweight of the girder cage 130 may be supported by theangle bracket 90 during the attachment process. Attach-ment of the girder 130 to the column having the inter-connection module 80 formed thereon is further accom-plished by extending splice sections of rebar along thegirder rebar members charged through the columngirder 130 and attaching the splice sections of rebarthereto, generally via ties, preferably wire ties. Girderrebar splice bars are changed horizontally through thecolumn cage 150. The girder splice bars are tied to thegirder cage bars. A minimum of eight feet of splicerebar is generally desired within the girder cage 130being attached to the column cage 150.

Splice member overlap length reduction is achieveddue to better confinement. Because of the uniform con-finement among the full length of the splice, tests haveshown that the required lap length is much less than thatrequired by code. Consequently shorter overlaps save asubstantial amount of reinforcement steel. If an oppos-ing girder cage 130 is attached to the interconnectionmodule 80, then the splice sections of rebar extendthrough the interconnection module 80 such that theyare attached to both opposing girder cages 130.

Referring now to FIG. 4a, the welded interconnec-tion 85 of the first 82, second 84, and third 86 rebar

1 15,392,580

1 2members is illustrated. Welded construction is pre-ferred, although those skilled in the art will recognize

recognize that various other sizes of rebar may likewise

that various other methods are likewise suitable.be suitable. A plurality of expandable grids 100, prefera-bly still shrink-wrapped, depend from the rebar sections --’

Referring now to FIGS. 5 and 5a, an expandable cageor grid bundle 100 is comprised of a plurality of individ-

112. Similarly, a plurality of interconnection modules 805

ual column grids 40. The grids 40 are attached togetherdepend from the rebar sections 112. Each interconnec-

via loops 102 disposed about adjacent rebar members,tion module 80 is preferably further supported by a

i.e. adjacent horizontal wire members 44 and/or adja-support 220 (FIG. 66). The expandable bundles 100

cent vertical rebar members 42. The loops 102 limit theexpand to till the distance between interconnectionmodules 80 in the manner illustrated in FIG. 5a. Col-

expansion of the wire cage 100 and define the final 10 umns up to sixty feet in height, the standard uncutpositions of the grids 40. The grids 40 preferably expandsuch that adjacent grids are approximately three inches

length of rebar as purchased from the mill, can easily be

apart after expansion. Similar construction is utilized infabricated utilizing the process of the present invention.

fabrication of an expandable cage or grid bundle com-With particular reference to FIG. 8, the charging

process is illustrated. During charging, a plurality ofprised of girder grids 60. The loops 102 are preferably 15 additional elongate rebar sections 116, preferably like-comprised of steel, however, those skilled in the art willrecognize that various other materials, e.g. copper,

wise formed of #11 rebar, are pushed through the open-

aluminum, plastic, rope, fabric, etc., are likewise suit-ings of the expandable cages or grid bundles 100 and

able. Additionally, tie wraps and/or perforated plasticinterconnection modules 80. Charging is preferably

wraps may be utilized as the loops 102.performed with the grid bundles 100 still shrink-

The column grids 40 (as well as the girder grids 60)20 wrapped. By charging the grid bundles 100 while they

can be configured such that they may be nested forare still shrink wrapped, the individual grids comprising

storage and transportation. Nesting allows each grid tothe bundles are maintained in a desired, i.e. collapsed or

be positioned as close as possible to adjacent grids, suchnonexpanded, configuration which facilitates their han-

that a compact assembly is formed. To nest the column 25dling and thus makes the charging process easier. This is

grids 40, for example, every other column grid 40 isaccomplished by pushing the rebar sections 112 and 116

turned around such that the first wire members 42, forthrough the plastic shrink wrap. The shrink wrap is

example, are disposed next to each other, i.e., one aboveremoved prior to expanding the grid bundle 100.

and one below. Thus, for each such turned grid, theEach of the elongate rebar sections 112 and 116 pass

through the ties 46 of the individual grids 40 comprisinglength of the assembly is reduced by the diameter of the 30 the grid bundle 100. The ties 46 are tightened afterwire member 42 and space is correspondingly con-served.

expanding the expandable grid bundle 100 to securely

The entire expandable cage or grid bundle, whetherattach the individual grids 40 to the charged rebar mem-

in a nested configuration or not, is preferably shrink-bers 112 and 116. Interconnection modules 80 are simi-larly attached at the desired locations along the charged

wrapped to facilitate handling. Shrink wrapping envel- 35 rebar sections.opes the grid bundle with plastic to prevent movementof the grids relative to one another during shipping and

After a steel reinforcing cage is formed as described

handling, as well as during the cage assembly process.above, forms, typically comprised of fiberglass or steel,

Referring now to FIGS. 6, 6a, and 6b, a horse 110are secured about the latticework or cage and concreteis then poured into the forms. As in prior art structural

supports upper elongate rebar sections 112. Lower 40 member construction, the concrete substantially encap-rebar sections 113 may be supported, as required. Thehorse comprises parallel base bars 210 which extend the

sulates the steel cage. Although the fabrication of a

distance of the structural member to be formed there-column cage according to the method of the present

upon, vertical support bars 212, and cross members 214invention is described above, the method of fabricatinga girder cage is an analogous process wherein girder

adjustably attached to the vertical support members 45 grids 60 are substituted for the column grids 40.212. Base cross members 218 interconnect the basemembers 210.

After pouring the concrete into the form, it is typi-

With particular reference to FIG. 6a, the height oftally vibrated to minimize voids or air pockets formed

each cross member 214 can be varied by looseningtherein during the pouring process. Use of the columngrids 40 or girder grids 60 of the present invention

adjustable fittings 216 and sliding the cross member 214 50 enhance both the pouring and void elimination pro-up or down as desired. Retightening the adjustablefitting 216 firmly secures the cross member 214 in place.

cesses. Pouring is facilitated by eliminating extraneous

With particular reference to FIG. 6b, adjustable sup-protuberances which would otherwise inhibit the flow

port 220 comprising support surface 222 disposed atopof concrete through the steel latticework of the cage.The locked ends 20 and 21 of the rectangular hoops 10

adjustable vertical support members 224 and attached 55 (shown in FIGS. la and lb) are eliminated. Thesesto cross member 226 may be utilized to support theinterconnection modules 80. As with the adjustable

superfluous members represent a substantial impedanceto the flow of concrete through the steel latticework

cross members 214, the height of the support surface222 is adjustable via adjustment couplings 228.

due to their large number. Furthermore, the amount ofsteel utilized in wire ties is reduced both by maximizing

Adjacent interconnection modules 80 are preferably 60 the efficiency of the attachment process through the usespaced approximately three feet six inches apart. Suchhorses 110 are utilized to support sections of rebar dur-

of pre-positioned wire ties 46 and by utilizing prefabri-

ing the charging process wherein columns and girderscated column 40 and girder 60 grids. The vibration or

are formed according to both the prior art and presentvoid elimination process is likewise enhanced through

invention.the elimination of superfluous steel since such protrud-

Referring now to FIGS. 7 and 8, horses 110 are illus-6 5 ing steel both contributes to the formation of voids and

trated supporting two elongate rebar sections 112, pref-inhibits their elimination.

erably formed of #ll rebar. Those skilled in the art willReferring now to FIG. 9, an interconnection module

80 having a plurality of elongate rebar sections 112 and

a

135,392.580

116 charged therethrough is illustrated. As can be seen,the rebar sections 112 and 116 extend through the open-ings in the interconnection module 80. The interconnec-tion module 80 may be secured to the elongate rebarmembers 112 and 116 via ties. Those skilled in the artwill recognize that various other means, i.e. welding,for securing the interconnection module 80 to the rebarmembers 112 and 116 are likewise suitable.

Referring now to FIGS. 10-13, a girder cage 130constructed according to the present invention is illus-trated. The girder generally comprises a plurality ofrebar members 132, preferably #ll, charged through aplurality of girder grids 60, at the comers thereof. Addi-tionally, rebar members 133 are charged intermediatethe comer rebar members 132.

,14

5Splice rebar members 182 interconnect opposing

girders 130. The splice rebar members 182 are disposedparallel to and adjacent the rebar members 132 compris-ing the girder cage. The splice rebar members 182 areattached to the rebar members 132 of the girder cagesvia ties. Those skilled in the art will recognize that

10 various other means of attaching the splice rebar mem-bers 182 to the girder rebar members 132 are l ikewise

1 5Additionally, cross members 134 and spool-type rol-

lers 136 (best shown in FIG. 12) may optionally beprovided to improve the charging process. The crossmembers 134 are welded at the appropriate heightsalong selected vertical rebar members 62 of girder grids60 to provide proper support for the rebar members 132charged therethrough. Rollers 136 are comprised offirst 138 and second 140 rebar supporting portions, eachdisposed outboard of corresponding partitions 142. Thepartitions 142 maintain positioning of the associatedrebar sections 132. The spool-type rollers 136 prefera-bly comprise a metal material, i .e. steel, although theymay alternatively comprise a plastic material, prefera-bly a low-friction plastic material such as TEFLON (aregistered trademark of Du Pont de Nemours, E. I., &Co., Inc.). Those skilled in the art will recognize thatvarious other materials are l ikewise suitable. Ties 46secure elongate rebar sections 132 ln position after theyhave been charged through the girder grids 60.

Referring now to FIG. 14, a column cage 150, such asthat being assembled in FIGS. 7 and 8, is being posi-tioned by crane 152. The expandable grid bundles 100have been expanded and secured in position via ties 46.The interconnecting modules have likewise been se-cured in position with ties 46. If concrete is appliedprior to erection, then rebar couplers, as shown inFIGS. 18 and 19, must be used to connect column sec-tion to column section and girders to columns.

Referring now to FIG. 15, a ductile frame 160 iscomprised of columns 150 and girders 130. The girders130 are attached to the columns 150 at interconnectionmodules 80. Distance “A” between adjacent girders ispreferably approximately thirteen feet and distance “B”between adjacent columns is preferably approximately30 feet. When a tall building must accommodate below-grade parking, columns must be spaced at approxi-mately thirty feet on center in both directions.

Referring now to FIGS. 16, 17, and 17a, the steelstructures or lattices associated with the interconnec-tion of girders 130 and columns 150 are illustrated.Split-sleeve snap-on rollers 180 (as best shown in FIG.17~) may optionally be installed upon any rebar mem-bers having other rebar members charged thereover tofacilitate such charging. Such split-sleeve snap-on rol-lers preferably comprise a metal material, such as steel.However, they may alternatively comprise a plasticmaterial, such as TEFLON. Those skilled in the art willrecognize that various other materials are likewise suit-able.

2 0

2 5

3 0

3 5

40

4 5

5 0

5 5

6 0

The split-sleeve snap-on roller is preferably contig-ured such that the split 181 may be pried apart oropened sufficiently to facilitate attachment thereof to arebar member or the like. Thus, such split-sleeve snap-

6 5

on rollers are disposable upon preformed column grids40, and interconnection modules 80 in order to facilitatethe charging of rebar members therethrough.

The rebar members 116 of the column 150 furthercomprise tapered portions such that they may readilyinterconnect to additional column rebar cage members190 for attachment thereto. Each attachment may beaccomplished via ties. Those skilled in the art will rec-ognize that various other means for attachment arelikewise suitable.

Referring now to FIGS. 18 and 19, the use of athreaded coupling 170 to interconnect columns and/orgirders is illustrated. The threaded coupling 170 is ini-tially threaded completely onto first threaded rebarmembers 172 which are partially embedded within acolumn 150 or a girder 130. Complimentary secondthreaded studs 174 are positioned in alignment and abut-ting relation to the first threaded studs 172 upon whichthe threaded couplings 170 are attached. The threadedcouplings 170 are then unthreaded partially from thefirst threaded studs 172 such that they thread upon thecomplimentary second threaded studs 174, thereby in-terconnecting the first threaded studs 172 and the com-plimentary second threaded studs 174. The threadedcouplings may optionally comprise a ductile material ormechanism to facilitate minor relative motion betweenthe columns and/or girders joined thereby.

It is understood that the exemplary ductile framedescribed herein and shown in the drawings representsonly a presently preferred embodiment of the invention.Indeed, various modifications and additions may bemade to such embodiment without departing from thespirit and scope of the invention. For example, the gridsmay be comprised of various materials and formed byvarious processes which provide a high strength, inte-gral construction. Also, members other than contempo-rary rebar, i.e. angle iron, square tubing, etc., may beutilized in the construction of the present invention.Furthermore, the grids need not be rectangular inshape, but rather need only conform generally in shapeto the cross-section of the structural member beingfabricated therewith. Additionally, those skilled in theart will recognize that stay-in-place forms may be uti-lized in the construction of columns, beams, and similarconstruction members according to the present inven-tion. The structures and methodology of the presentinvention need not be limited to use in the fabrication ofcolumns and girders. Rather, those skilled in the art willrecognize that the structures and methodology of thepresent invention may be utilized in the construction ofvarious other structural members as well. Thus, theseand other modifications and additions may be obviousto those skilled in the art and may be implemented toadapt the present invention for use in a variety of differ-ent applications.

What is claimed is:1. A ductile reinforced concrete construction mem-

ber comprising:

suitable.

5,392,58015 16

(a) a plurality of prefabricated grids disposed in gen-erally parallel stacked relationship;

(b) a plurality of rebar members charged through saidprefabricated grids; and

10. The ductile reinforced concrete constructionmember as recited in claim 4 wherein said links com-prise wire links.

(c) concrete generally encapsulating said grids and 5rebar members;

(d) at least one roller formed upon at least one of saidgrids such that at least one of said rebar membersmay be charged through said grid thereover, saidroller reducing friction between said rebar member 1Oand said grid to enhance the charging process priorto encapsulation of said grids and said rebar mem-bers in concrete.

2. The ductile reinforced concrete construction mem-ber as recited in claim 1 wherein said roller comprises a 15plurality of partitions, said rebar members being sepa-rated from one another by said partitions.

3. The ductile reinforced concrete construction mem-ber as recited in claim 1 wherein said roller comprises asplit-sleeve snap-on roller which is attachable to said ,n. _

11. The ductile reinforced concrete constructionmember as recited in claim 7 further comprising at leastone roller formed upon at least one of said grids suchthat at least one of said rebar members may be chargedthrough said grid thereover, said roller reducing fric-tion between said rebar member and said grid to en-hance the charging process.

12. The ductile reinforced concrete constructionmember as recited in claim 11 wherein said roller com-prises a plurality of partitions, said rebar members beingseparated from one another by said partitions.

13. The ductile reinforced concrete constructionmember as recited in claim 11 wherein said roller com-prises a split-sleeve snap-on roller which is attachable tosaid grid.

14. A ductile reinforced concrete construction mem-ber comprising: .

g n d . S” a) a plurality of prefabricated grids disposed m gener-

4. A grid for use in the fabrication of ductile rein-ally parallel stacked relationship, each of said grids

forced concrete construction members, said grid com-comprised of intersecting first and second rebar

prising:members;

(a) a plurality of first generally parallel steel wireb) a plurality of links interconnecting adjacent gener-

members; 2 5ally parallel stacked grids for defining a distancetherebetween;

(b) a plurality of second generally parallel steel wiremembers welded to said plurality of first generally

c) a plurality of third rebar members charged throughsaid prefabricated grids;

parallel steel wire members, said first wire mem- d) concrete generally encapsulating said grids andbers being generally perpendicular to said second rebar members; andwire members such that intersections thereof are 30 e) a plurality of wire ties disposed at a plurality of theformed; intersections of said first and second rebar mem-

(c) said first and second wire members defining a bers, one end of said wire ties being attached firmlyrectangle; and to the first rebar member and the opposite end

(d) at least one roller disposed upon at least one of thereof being attached loosely to the second rebarsaid first and second wire members such that at 35 member to facilitate tightening thereof about saidleast one rebar member may be changed through third rebar members charged through said grids.

said grid thereover, said roller reducing friction15. The ductile reinforced concrete construction

between said rebar member and said grid to en-member as recited in claim 14 wherein said links com-

hance the changing process.prise wire links.

16. A ductile reinforced concrete construction mem-5. The grid as recited in claim 4 wherein said roller J.O her comprising:

comprises at least one partition.6. The grid as recited in claim 4 wherein said roller

a) a plurality of prefabricated grids disposed in gener-

comprises a split-sleeve snap-on roller which is attach-ally parallel stacked relationship, each of said grids

able to said grid.comprised of intersecting first and second rebar

7. A ductile reinforced concrete construction mem- 45members;

ber comprising:b) a plurality of third rebar members charged through

a) a plurality of prefabricated grids disposed in gener-said prefabricated grids;

ally parallel stacked relationship, each of said gridsc) at least one roller formed upon at least one of said

grids such that at least one of said third rebar mem-comprised of intersecting first and second rebar bers may be charged through said grid thereover,members;

b) a plurality of third rebar members charged through 5osaid roller reducing friction between said rebarmember and said grid to enhance the charging

said prefabricated grids; process;c) concrete generally encapsulating said grids and d) concrete generally encapsulating said grids and

rebar members; and rebar members; andd) a plurality of wire ties disposed at a plurality of the e) a plurality of wire ties disposed at a plurality of the

intersections of said first and second rebar mem- 55 intersections of said first and second rebar mem-bers, one end of said wire ties being attached fumly bers, one end of said wire ties being attached tirmly

to the first rebar member and the opposite end to the first rebar member and the opposite endthereof being attached loosely to the second rebar thereof being attached loosely to the second rebar

member to facilitate tightening thereof about said member to facilitate tightening thereof about said

third rebar members charged through said grids. 60third rebar members charged through said grids.

8. The ductile reinforced concrete construction mem-17. The ductile reinforced concrete construction

ber as recited in claim 7 wherein said wire ties are at-member as recited in claim 16 wherein said roller com-

tached firmly to the first rebar member via at least oneprises a plurality of partitions, said rebar members being

of welding and hot glue.separated from one another by said partitions.

9. The ductile reinforced concrete construction mem- 6518. The ductile reinforced concrete construction

ber as recited in claim 7 further comprising a pluralitymember as recited in claim 16 wherein said roller com-

of links interconnecting adjacent grids for defining aprises a split-sleeve snap-on roller which is attachable to

distance therebetween,said grid.

* * * * *