The Dogbone Connection: Part II -

ated states of triaxial tension,etc. The reinforcement reducesstress levels within this vulnera-ble region near the column face,and forces the large stresses andinelastic strains further into thebeam. Reinforcing the connec-tion, however, increases its cost.Further, if excessive reinforce-ment is used, new problems canbe created resulting from theneed for very large welds withhigh shrinkage, and higherdegrees of restraint and triaxialtension.

An alternative to reinforcing amoment connection that providesbenefits similar to reinforce-ment, but may avoid some of thedisadvantages, is the “dogbone”moment connection. A distin-guishing feature of the dogbone,also known as the ReducedBeam Section (RBS) connection,is that portions of the beamflange are trimmed away in theregion adjacent to the beam-to-column connection (Figure 1).Various shape cutouts are possi-ble. The result is similar to rein-forcement, i.e., the connection isstronger than the beam. In this

case, however, the connection ismade stronger than the beamnot by increasing the strength ofthe connection, but rather bydecreasing the strength of thebeam. The dogbone can beviewed as a ductile fuse. It forcesyielding to occur within thereduced section of the beam, anarea that can sustain largeinelastic strains. At the sametime, the dogbone acts as a fuse,limiting stress at the less ductileregion near the face of the col-umn. Previous work has beenconducted on the constant cutand tapered cut dogbone shapesshown in Figure 1. In the case ofthe tapered cut, the taper isintended to follow the momentdiagram in order to promote uni-form yielding over the full lengthof the dogbone.

At first glance, it may seemcounterintuitive that removing aportion of a structure actuallyimproves the performance of thestructure. In the case of the dog-bone, however, this is exactly thecase! The dogbone results in onlya small reduction in lateralstrength and stiffness of a framebut can provide a large increasein ductility, the key to survival ofa structure in a strong earth-quake. Trading a small amountof strength in return for a largeamount of ductility representsan excellent bargain for earth-quake resistant design.

The size of moment framebeams is normally controlled bycode-mandated drift limitationsrather than by code strengthrequirements. The dogbone gen-erally results in only a slight

Modern Steel Construction / August 1996

By Michael D. Engelhardt,Ted Winneberger, Andrew J.

Zekany and Timothy J.Potyraj

SINCE THE 1994 NORTHRIDGEEARTHQUAKE, INTENSIVERESEARCH AND TESTING

EFFORTS have been underway tofind better methods to designand construct seismic resistantsteel moment connections. Awide variety of solutions havebeen proposed over the last twoyears, many of which haveshown greatly improved perfor-mance in the laboratory com-pared to the previous “Pre-Northridge” connection. Theoverall goal in the developmentof new connections is to providehighly ductile response, reliableperformance, and economy.

Many of the new moment con-nections combine improvementsin welding with some type ofreinforcement at the connection(cover plates, ribs, haunches,side plates, etc.). The purpose ofthe reinforcement, in the mostgeneral terms, is to provide aconnection that is stronger thanthe beam. A strong earthquakewould be expected to developplastic hinges at the beam endsin a traditional fully restrained(FR) moment frame. The rein-forcement is intended to forcethe plastic hinge away from theface of the column, where prema-ture fractures can occur due topotential weld defects, stressconcentrations at weld accessholes, stress concentrations dueto column flange bending, highlevels of restraint and the associ-

THE DOGBONECONNECTION: PART II

Selectively trimming a portion of a beam allowsconnection strength to exceed beam strength without

the need to develop a stronger connection

Figure 1: Typical “dogbones”

decrease in frame stiffness.Consequently, in many practicalcases, the use of the dogbone willlikely not necessitate a change ofbeam size in order to meet codestrength and stiffness require-ments.

A significant amount ofresearch and full scale testinghas already been done on thedogbone concept. An article byNestor R. Iwankiw, P.E., andCharles J. Carter in the April1996 Modern Steel Constructionsummarized some of the recenttesting. Early work was conduct-ed by S.J. Chen and C.H. Yeh inTaiwan, and by A. Plumier inBelgium. More recently, addi-tional work has been conductedby AISC at Smith-EmeryCompany in Los Angeles, and byOve-Arup & Partners workingwith the University of Californiaat San Diego. This previousresearch, conducted on eitherconstant cut or tapered cut dog-bones (Figure 1) has shown verypromising performance. Typ-ically, large plastic rotationshave been obtained. In a fewcases, fractures developed duringtesting, either at the beamflange to column connection orwithin the dogbone, but onlyafter large levels of plastic rota-tion were achieved.

Based on the earlier laborato-ry successes of the dogbone, thisconcept was recently applied to a25-story steel office building inSalt Lake City. In applying thisconcept, some further refine-ments were made to the dogboneapproach and verified by fullscale laboratory testing. Theremainder of this articledescribes this building project,and the associated connectiontesting program

AMERICAN STORES COMPANYHEADQUARTERS

When the American StoresCompany and HowaConstruction Company decidedto build the new AmericanStores Headquarters Building inSalt Lake City, HKS Inc. ofDallas designed a 25 story,650,000-sq.-ft. structure with

steel moment frames as its pri-mary lateral force resisting sys-tem. W&W Steel Company ofOklahoma City was responsiblefor detailing, fabricating anderecting the building’s 7,900 tonsof structural steel.

The typical floor of the build-ing is triangular shaped in plan(Figure 2). The plan measures302-ft. along the long face and121-ft. along the width. A promi-nent feature of the plan is anenclosed atrium on the west sideof the building. The atrium con-sists of a series of individualfour-story and two-story openspaces that stack above eachother throughout the height ofthe building. Surrounding theatriums are the elevator coresand lobbies, conference rooms

and typical office space. Theoffice space is designed for maxi-mum flexibility and is pro-grammed to be an open spaceplan layout, requiring 43-ft.-4-in.spans for the floor framing.

The floor framing wasdesigned using composite steelbeams with 31/4-in. lightweightconcrete slabs over 3-in. compos-ite deck. The AISC Load andResistance Factor DesignSpecification (LRFD) was uti-lized in the design of the beamsand columns. ASTM A572 Gr. 50steel was used for all members.

The primary frames are locat-ed around the building perimeterand around the elevator cores. Athree dimensional perspectiveillustration of the lateral fram-ing members is shown in Figure


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Figure 2 (above): Typical floorframing plan

Figure 3 (left): 3D view of lateralframing members

A test program with fivelarge-scale specimens wasundertaken to evaluate suitabili-ty of the dogbone for use in the2,000 moment connections of theAmerican Stores Companyheadquarters building. The spec-imens, designated DB1 to DB5are outlined in Table 1. The con-cept adopted for these specimenswas to combine the dogbone cutin the beam, together with ahigh quality welded beam-to-col-umn connection at the face of thecolumn. Both welding and designimprovements were incorporatedinto the beam-to-column connec-tion to provide significantlyimproved capabilities comparedto the Pre-Northridge type con-nection. With these improvedconnection capabilities, togetherwith a reduced demand on theconnection due to the presence ofthe dogbone, the hope was for aseismic resistant moment con-nection system capable of devel-oping large plastic rotationsunder severe cyclic loading con-ditions.

For the beam-to-column con-nection at the face of the column,each of the five specimens usedessentially the same detail. Atypical detail is illustrated inFigure 4. An all-welded connec-tion was used, in which the beamflanges and beam web were con-nected to the column flangeusing complete joint penetrationgroove welds. It was believedthat the welded web connection,although somewhat more costlythan a more conventional boltedweb connection, would provide ahigher level of ductility. Thewelded web connection cantransfer significant momentfrom the beam to the column,thereby reducing demands onthe beam flange welds. The rela-tively thin shear tab provided atthe beam web connection servesto support the beam during erec-tion and also acts as backing forthe beam web groove weld.

Testing done since theNorthridge Earthquake hasraised questions on previousdesign criteria for continuityplates in seismic resistant


Spec. Column Beam Dogbone Plastic CommentsType Rotation

DB1 W14x426 W36x160 Constant Cut 0.020 rad. Fracture at dogboneDB2 W14x426 W36x150 Radius Cut 0.030 rad. No conn. failureDB3 W14x426 W36x170 Radius Cut 0.038 rad. No conn. failureDB4 W14x426 W36x194 Radius Cut 0.037 rad. No. conn. failureDB5 W14x257 W30x148 Radius Cut 0.040 rad. No conn. failure;

signif. column panelzone participation

Table 1: Description of Test Specimens & Results

Table 2: Beam Tensile Properties

Spec. Beam Yield Stress (ksi) Tensile Strength (ksi)Flange Web Flange Web

DB1 W36x160 54.7 53.5 75.6 79.2DB2 W36x150 41.4 47.1 58.7 61.8DB3 W36x170 58.0 58.5 73.0 76.7DB4 W36x194 38.5 43.6 58.6 59.8DB5 W30x148 46.6 48.5 64.5 65.4

3. W36 and W40 frame columnsizes were utilized to controldrift. The building design calledfor 1,000 moment resistingframe beams, ranging in sizefrom W27x114 to W36x210.

Located in UBC Seismic Zone3, earthquake safety was animportant design concern for thisbuilding. The design and con-struction team was faced withthe challenge of developing amoment resisting connectionthat would perform as intendedby the UBC for a SpecialMoment Resisting Frame.Working together with TheUniversity of Texas at Austin,HKS and W&W Steel exploredseveral options, including rein-forced connections, bolted con-nections, and the dogbone con-nection. Connection design wassomewhat complicated by thevery short 17-ft. clear spans onmany of the building’s momentframe girders since connectionconcepts that move the plastichinge away from the face of thecolumn are more difficult toimplement on short spans. Thehigh moment gradients associat-ed with short spans cause a largeamplification of moment fromthe point of plastic hinge forma-tion back to the face of the col-

umn. This, in turn, increasesstress levels at the face of thecolumn, and negates some thebeneficial effects of forcing theplastic hinge away from the col-umn.

Considering the options, thedogbone emerged as the mostcost effective solution for thisproject. Although the dogbonealready had a good track recordin earlier testing, Andy Zekanyof HKS requested additionaltesting using representative W36beams. These tests would permitevaluation of details specific tothis project, and help build confi-dence in the connection.Remarkably, the decision wasmade to embark upon this testprogram after construction onthe American Stores CompanyHeadquarters had already begunon an extremely fast track sched-ule. Stuart King with AmericanStores and Rick Howa of HowaConstruction required the mosteffective and economical momentconnection available for seismic-resistant steel framing. Theirconsistent direction in meetingthis goal and their support of theengineers’ recommendations ledto the test program.

TEST PROGRAM

moment connections. For thisproject, the decision was made toprovide continuity plates at allconnections, with the thicknesschosen to be comparable to thebeam flange thickness. For thetest specimens, beam flangethickness ranged from 0.94 to1.26 in. One-in. thick continuityplates were used for all speci-mens.

Welding at the beam-to-col-umn connection was accom-plished by self-shielded flux-cored arc welding process usingan electrode with a minimumspecified Charpy V-Notch tough-ness of 20 ft.-lbs. at -20 degreesF. For the beam flange groovewelds, properly oriented weldrunoff tabs were used, and thenremoved after completion of theweld. At the bottom flangegroove weld, the backing bar wasremoved, and a reinforcing filletweld was placed at the root ofthe weld joint. Removing thebacking bar permits visualinspection of the weld root, mini-mizing the chance of undetectedroot defects, and eliminating anypossible notch effects of thebacking bar.

The top flange backing barwas left in place. There were sev-eral reasons for this. First, rootdefects are less likely at the topflange since neither the grooveweld nor the ultrasonic testing ofthe groove weld is interrupted bythe beam web, as they are at thebottom flange. Further, removalof the top flange backing bar ismore difficult and costly than atthe bottom flange, since the arc-gouging must be done throughthe weld access hole.Consequently, for this projectthe top backing bar was left inplace. However, a continuous fil-let weld was provided betweenthe backing bar and the columnflange (see Figure 4). From atheoretical perspective, this filletweld reduces the potential notcheffect of a left in place backingbar.

For welding quality control,both in-process inspection andultrasonic testing were specified.Inspection and testing were

based on AWS D1.1-94,Structural Welding Code - Steel.Items emphasized for in processinspection included checking thejoint fit-up, preheat, and enforc-ing the Welding ProcedureSpecification (WPS) for the pro-ject. Ultrasonic testing was donefor the complete joint penetra-tion groove welds, with accep-tance criteria based on Table 8.2of AWS D1.1-94.

The member sizes used for thetest specimens are listed inTable 1. Each of the test speci-men columns were A572 Gr. 50steel. Four of the specimens usedW14x426 columns, taken fromthree different heats of steel. Forthe beam sections used in thetests, mill certificates were notavailable. Tensile coupon testswere run on the beam sections,and the results are shown inTable 2. Actual beam flangeyield stresses varied from 38.5ksi to 58 ksi. Consequently, awide range of beam strengthswere represented in the testspecimens. Member sizes inSpecimens DB1 to DB4 wereselected to force virtually all ofthe inelastic deformations intothe beam. Specimen DB5 wassized to encourage shear yieldingof the column panel zone, inorder to evaluate its effects onthe dogbone connection.

TEST RESULTS

Testing was conducted at TheUniversity of Texas FergusonLaboratory. All tests were con-ducted on single cantilever typespecimens, with cyclic loadsapplied to the tip of the beam fol-lowing the loading protocol ofATC-24. The goal of the test pro-gram was to develop plastic rota-tions of at least 0.03 radian, assuggested by the SAC InterimGuidelines.

The first specimen, DB1, com-bined the all-welded connectiondescribed above with a constantcut dogbone (Figure 1(a)).Previous successful tests hadbeen run on both constant cutand tapered cut dogbones. Theconstant cut was elected for thisfirst test. During testing,

Specimen DB1 showed excellentperformance in the initial inelas-tic cycles. However, a fracturedeveloped within the dogbone atthe end of the flat portion of thecutout that was closest to theface of the column. A stress con-centration resulting from thechange of cross-section at thispoint apparently contributed tothis fracture. Despite this frac-ture, the specimen still sus-tained 0.02 radian of plasticrotation. Further, there were nosigns of distress anywhere with-in the beam-to-column connec-tion at the face of the column.

Although the first test did notmeet full performance expecta-tions, the results were stillencouraging. It appeared thatachievement of the higher per-formance goal might be possibleby changing the shape or dimen-sions of the dogbone cutout toreduce stress concentrationswithin this region. In order toprovide a cutout region withminimum stress concentrationsand one that would still be eco-nomical to fabricate, the conceptof a circular radius-cut dogbonewas suggested by TedWinneberger of W&W Steel Co.This ultimately proved success-ful in the testing program.

The remaining four test speci-mens were all constructed with aradius-cut dogbone. Figure 5shows the shape and dimensions.The same all-welded beam-to-column connection described ear-lier was used. A typical speci-men, DB4, is shown in Figure 4.

Each of the four radius-cutdogbone specimens (DB2 to DB5)showed excellent performance.The plastic rotations developedby each specimen at the end ofthe test are listed in Table 1. Ineach case, testing was stopped asa result of limitations in the testequipment, rather than becauseof specimen failure. Conse-quently, the specimens wouldhave likely developed largerplastic rotations had the testingbeen continued.

At large plastic rotations, thebeams of the test specimens typi-cally exhibited considerable


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twist that accompanied localflange and web buckling in thebeam. This resulted in a gradualreduction in flexural strength.Testing was stopped in each caseto avoid damage to the testequipment from this twisting. Itshould be noted however thatthe twisting experienced bythese dogbone specimens was nomore severe, and perhaps some-what less severe, than reinforcedconnections previously tested atThe University of Texas.

At the point at which testingwas stopped, no fractures haddeveloped within the dogboneregion for any of the radius-cutspecimens. Further no failuresoccurred at the beam-to-columnconnections. The connection onSpecimen DB3 showed smallcracks near the weld access holesthat developed during the cyclesat 0.02 radian. These smallcracks, however, did not growduring the remainder of the testand had no impact on theresponse of the specimen. Forthe remaining specimens, theweld access holes were enlargedand were provided with asmoother transition to the beamflange. The small cracksobserved in DB3 were notobserved in the remaining speci-mens.

Figure 6 shows photos ofSpecimen DB4 during testing.Figure 6(a) is a view lookingdown at the top beam flange at aplastic rotation of 0.012 radian.The darkened regions are areaswhere the whitewash coatinghas flaked off, providing a quali-tative indication of where yield-ing has occurred. This photoshows yielding concentratedwithin the dogbone region of thebeam, and indicates the connec-tion was performing as intended.Figure 6(b) shows the specimenat plastic rotation of 0.022 radi-an. Finally, Figure 6(c) showsthe specimen at a plastic rota-tion of 0.037 radian, the point atwhich testing was stopped.

As noted earlier, at large plas-tic rotations the specimensexhibited flange and web localbuckling within the plastic hinge


Figure 4 (top): Test specimen DB4

Figure 5 (above): Radius cut dogbones

region. Flange buckling is visiblein Figure 6(c). Such local buck-ling has been observed in manytests on reinforced or other modi-fied connection concepts.However, this severe local buck-ling typically occurs at very largeplastic rotations. Figure 6(b)shows Specimen DB4 at a plasticrotation of 0.022 radian. At thislevel of demand, the degree oflocal buckling is still very slight,and in fact, is hardly noticeable.Analytical studies of steelmoment frame buildings affectedby the Northridge Earthquakesuggest that most buildingsexperienced maximum plasticjoint rotations on the order of0.005 to 0.00 radian. Under thislevel of demand, these test speci-mens had no visible damage,other than yielding patternsindicated by whitewash flaking.Such connections would likelyrequire no repair after experi-encing this level of demand.

For all test specimens, withthe exception of DB5, plasticrotations were developed byinelastic deformations in thebeams. Specimen DB5 wasdesigned to permit significantshear yielding of the columnpanel zone. During testing, agreat deal of yielding was in factobserved in the panel zone.Analysis of test data indicatesthat of the total plastic rotationof 0.040 radian developed byDB5, approximately 25% wascontributed by the column panelzone. For this specimen, inelastic


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deformations of the panel zonehad no apparent detrimentaleffect on the connection, and con-tributed to the ductility of thetest specimen.

Based on the successfulresults of this testing program,the overall cyclic loading perfor-mance of the radius-cut dogboneconnection was judged as excel-lent.

COST COMPARISONS

The test program indicatedthat the radius-cut dogbone con-nection was capable of providinga high level of performance.However, because of the large

number of moment connectionsin this building, the cost of thedogbone connection relative toother options was also a criticalconcern.

To address the issue of cost,W&W Steel developed cost esti-mates for a number of momentconnection options for this pro-ject. The results are shown inTable 3. Relative costs are pro-vided with respect to the Pre-Northridge welded flange-boltedweb moment connection. Costcomparisons were based on aW36x194 girder of A572 Gr. 50steel with weld metal toughnessrequirements for all cases except

Figure 6a (above): View of beamflange of specimen DB4 at 0.012rad. plastic rotation (column is atleft)

Figure 6b (left): Specimen at0.022 rad. plastic rotation

Figure 6c (top): Specimen at endof test; plastic rotation equals0.037 rad.

Connection Type RelativeCost

Pre-Northridge weldedflange-bolted web 1.00Radius-cut dogbone 1.71Constant or taperedcut dogbone 2.18Cover plate 2.50Flange ribs 2.91Bottom haunch 3.01Proprietary side plates 3.76Side plates 3.96Top & bottom haunch 4.00Column tree 6.38

Table 3: Cost Comparisons

dimensions as small as possible,in order to minimize the amplifi-cation of moment from the hingelocation in the dogbone to theface of the column. The dimen-sion “a” must be large enough,however, to permit stress in thereduced beam flange to spreaduniformly over the flange widthat the face of the column.Similarly, dimension “b” shouldbe large enough to avoid exces-sive inelastic strains in the dog-bone. Consequently, the suggest-ed dimensions above are acompromise between differentrequirements.

The depth of the cut, dimen-sion “c” in Figure 5 is a criticaldimension for the dogbone. Thefollowing approach was used todetermine this dimension. First,it was assumed that the maxi-mum moment that can developat midlength of the dogbone wasequal to the plastic moment ofthis reduced section, increasedby 10 to 15 percent to allow forstrain hardening. This momentwas then projected to the face ofthe column using a moment gra-dient based on an assumed pointof inflection at midspan of thebeam. The maximum moment atthe face of the column was thenlimited to approximately 90 to100 percent of the plasticmoment of the full cross sectionof the beam. It was believed thatthe all-welded connection com-bined with the welding detailsused in these tests was capableof sustaining such levels of bend-ing moment. The reduced beamsections were also checked forconformance with flexuralstrength requirements of theLRFD Specification for all fac-tored gravity and lateral loadcombinations. Following thisbasic approach, the depth of cut,“c,” was chosen. For all of theradius-cut specimens, the depthof cut resulted in removingapproximately 40 percent of thebeam flange width.

The maximum moment devel-oped at the face of the columncan be reduced by increasing thedepth of cut in the dogbone. Thewriters view removal of about 50


Figure 7:Mechanizedplasma arccutting ofdogbones infabrication shop

the Pre-Northridge connection.The various connection typeslisted in Table 3, other than theradius-cut dogbone, are connec-tion options illustrated in theSAC Interim Guidelines. Thecost data presented in Table 3were developed for this project,and will vary for other projectsdepending upon location, laborfactors, and connection designvariations.

The cost comparisons for thisproject indicated that the radius-cut dogbone was the most eco-nomical alternative of all theoptions considered. Based on thesuccessful testing program, com-bined with the favorable econom-ics, the radius-cut dogbonemoment connection was acceptedfor use on the American StoresCompany HeadquartersBuilding.

DESIGN AND FABRICATIONCONSIDERATIONS

In designing the radius-cutdogbone test specimens, it wasnecessary to establish dimen-sions of the dogbone. Key dimen-sions are shown in Figure 5, andwere established based on thejudgment of the writers. Thisjudgment relied on these testresults, results of previous dog-bone tests, and experience withother connection test programsover the last several years.Based on this judgment, the dis-tance “a” from the face of the col-umn to the start of the dogbonecut was chosen to be approxi-mately 50 to 75 percent of thebeam flange width. The length ofthe cut, dimension “b” in Figure5, was chosen in the range ofabout 65 to 85 percent of thebeam depth. In general, it ispreferable to keep the “a” and “b”

percent of the beam flange widthas a maximum practical cut.Note that for a given depth ofcut, a greater reduction inmoment at the face of the col-umn is possible in longer spanbeams with smaller moment gra-dients. If further reduction ofstress at the face of the columnis desired, some reinforcementcould be added to the connection,for example, thin cover plates orribs. In these tests, the actualmaximum moments developed atthe face of the column rangedfrom 92 percent to 113 percent ofthe actual plastic moment of thebeam. These moments were sus-tained without connection fail-ure. Consequently, no additionalreinforcement was provided atthe connection. It was felt thatsuch additional reinforcementwould largely negate the econo-my of this connection and wasunnecessary.

Once the length of the dog-bone “b” and depth of cut “c”have been chosen, the radius ofthe cut follows simply from thegeometry of a circular arc, asindicated by the formula inFigure 5.

Once the radius-cut dogbonewas accepted for use on theAmerican Stores Company build-ing, W&W Steel was faced withthe task of cutting dogbones intoboth flanges of both ends of1,000 moment frame girders.This required making 8,000 cuts.In order to make these cuts aseconomically as possible, W&Wdevised a mechanized processemploying plasma arc cutting.Figure 7 shows two cuts beingmade simultaneously in the fab-rication shop. The mechanizedplasma arc cut left a very highquality surface. The cutting wasfollowed by the use of a 3M pad-dle wheel grinder. Grinding wasdone parallel to the beam flangeto minimize stress concentra-tions due to grinding marks.

Figure 8 shows views ofmoment frame girders withradius-cut dogbone moment con-nections during erection at theconstruction site in Salt LakeCity. The structural steel fram-

ing is expected to be completedin November of 1996.

CONCLUSIONS

The test program conductedon the radius-cut dogbone con-nection showed excellent perfor-mance. Together with a numberof other connection types devisedand tested since the NorthridgeEarthquake, the dogbone connec-tion promises to deliver a muchhigher level of ductility and safe-ty as compared to the “Pre-Northridge” moment connection.

Structural engineers can nowchoose from a fairly wide varietyof seismic resistant moment con-

nection concepts that haveshown good performance in labo-ratory cyclic loading tests.Engineers must carefully consid-er currently available test datacombined with the economics ofa project when choosing the mostappropriate moment connectiondetail. This represents a rapidlychanging picture in the currentenvironment of intensiveresearch and testing. Based onthe experiences from this project,however, the dogbone connectionappears to be one of the morepromising moment connectionconcepts capable of deliveringboth performance and economy.

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Figures 8a & 8b: Moment frame during erection

Michael D. Engelhardt, is anAssociate Professor of CivilEngineering, The University ofTexas at Austin, Ted Winne-berger, is Senior Vice President,Engineering, W&W SteelCompany, Oklahoma City, OK,Andrew J. Zekany, is VicePresident, Structural Eng-ineering, HKS Inc., Dallas, andTimothy J. Potyraj, is aGraduate Research Assistant,The University of Texas atAustin. The testing program wasfinancially sponsored by W&WSteel Co. and the AmericanInstitute of Steel Construction,Inc. Additional support was pro-vided through National ScienceFoundation Grant Nos. CMS-9358186 and CMS-9416287. Thewriters thank Nestor Iwankiwand Charlie Carter of AISC, Inc.


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The Dogbone Connection: Part II -