Presents the major design and construction features ofthe East Huntington Bridge over the Ohio River in WestVirginia. The author discusses the conceptual plan,component design and erection method used to buildonly the second, long span prestressed concretecable stayed bridge completed in North America.

Design and Construction ofthe East Huntington Bridge

Arvid GrantPrincipal EngineerArvid Grant & Associates, Inc.Olympia, Washington

The East Huntington Bridge (Fig. 1)over the Ohio River in West Virginia

is the second, long span, precast pre-st essed concrete cable stayed bridgecompleted in North America. The proj-ect is an extension of the successfulfeatures incorporated in our firm's firstcable stayed bridge built over the Col-umbia River at Pasco-Kennewick. E•4

This paper will describe the new designelements of the East Huntington Bridgeand discuss some of the key features in-volved in the design and construction ofcable stayed bridges.

In order to promote engineering de-velopment, the United States govern-ment requires two different competingdesigns for all major bridges. When analternate concrete design was au-thorized tor the East Huntington Bridge,a steel girder system had already beencompleted. Also, the main river piers forthe designed steel system had alreadybeen built.

In competitive construction contractbidding for both designs, steel and con-crete, the concrete alternate received a$1.0,000,000 lower bid ($23,500,000 ver-

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Fig. 1, Scale model of the East Huntington Bridge.

sus $33,500,000) and was accepted. Thebridge was opened to traffic in August1985.

The East Huntington Bridge is a pre-cast prestressed concrete cable stayedbridge with one tower only and mainspans of 900 and 608 ft (274 and 184 m).The structure is built using 250 ton (227t) prefabricated high strength pre-stressed concrete elements and incor-porates steel floor beams in a hybrid ar-rangement.

The bridge's dynamically insensitivestructural system is lighter than concretecable stayed bridges built earlier, and isespecially suitable for spans longer than1650 ft (500 m) without modification.

The southern 640 ft (195 m) of the2000 ft (610 m) long bridge girder wasbuilt using the cast-in-place segmentalcantilever method and travelling form-work; the remainder of the girder wasassembled segmentally using 45 ft (13.7m) long, 250 ton (227 t) precast concrete

elements. The main section of thebridge (Fig. 2) is supported from a 420 ft(128 m) high stay cable tower and 62

stay cables. The two stay cable sup-ported spans — 900 and 608 ft (274 and185 m) long — are of a constant 5 ft (1.52m) depth and incorporate steel cross-beams in the precast elements.

Only two expansion joints accommo-date longitudinal movements in the2000 ft (610 m) girder. At the bridgetower, the girder is permitted to moveonly vertically. This structural con-figuration comprises one-half of a tradi-tional, symmetrical two tower cablestayed bridge with an equivalent mainspan of 1650 ft (500 m), proving thatsegmental concrete cable stayed bridgescan be built to accommodate very longspans.

The plan, elevation and typical crosssection of the bridge are shown in Fig. 2.

Special Design ConsiderationsThe presence of the previously con-

structed piers, which were designed tosupport the originally intended steelcable stayed bridge, required that theconcrete alternate not exceed the load

PCI JOURNALJanuary-February 1987 21

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Fig. 2. Plan, elevation and typical cross section of East Huntington Bridge.

Fig. 3. A 250 ton (227 t) precast girder segment being transported to project site.

carrying capacities of the existing piersand foundations.

All major bridges built earlier in theEast Huntington area are steel and useof concrete as a primary structural mate-rial was not well established. The ob-jective for the concrete design was todevelop a system that was not too heavy,yet could accept all loads and forcesnecessary for satisfactory service anddurability.

A research program was initiated priorto design to develop applicable data onlocal production and availability of highstrength concrete. As a result of thesepreparations, a 28 (lay concrete designstrength of 8000 psi (55 MPa) wasadopted.

Reasons for SelectingVery High Strength Concrete

Long term durability is the uppermostpriority of any new bridge. For concrete,the density of the material, wear resis-tance, and residual tensile stress capac-ity are the features which fulfill thisquality. Although high strength con-cretes have been found to be less ductilethan conventional concretes at the ulti-mate load state, very high strength con-cretes can assume a broader spectrum ofstresses at normal loading ranges. Thisis due primarily to the fact that they are

more dense and have a higher tensilestress capacity than ordinary con-cretes.

Perhaps the most important propertyis the residual tensile stress capacity ofvery high strength concrete to resist themany small, cumulative and incidentalservice load effects which may lead tothe structure's slow deterioration. TheEast Huntington Bridge incorporatedprecasting techniques for low water-cement ratio, densely consolidated con-cretes.

Hybridization ofSteel and Concrete

Reinforced concrete by its very con-stitution is a hybrid material. When thedesigner extends this technique evenfurther, via hybridization of major steelmembers with concrete elements, notonly can member size and structuralweight be reduced, but so can overallunit cost.

In order to achieve these benefits, thedesigner must also adequately providefor temperature changes and distribu-tion forces. In the East HuntingtonBridge, the successful interactive ar-rangement of the steel and concretemembers reduced the bridge's size,weight and cost, as well as the complex-ity of the required workmanship.

PCI JOURNALIJanuary-February 1987 23

Fig. 4, The southern portion of the bridge was built using cast-in-place segmentalcantilever construction and traveling formwork.

Concrete GirderThe 640 ft (195 m) long bridge girder

on the south approach is of the tradi-tional, varying depth, continuous boxgirder design. The high concretestrength permitted a girder with a veryslender shape, only 13 ft (4 in) deep overthe piers, varying to less than 7 ft (2 m)elsewhere.

The cable stayed part of the concretegirder is made tip of precast concreteelements, 45 ft (13.6 m) long, 40 ft (12.2m) wide, 5 ft (1.5 m) deep and weighing250 tons (227 t) each. Each precast con-crete girder element has anchorages fortwo stay cables, one in each side of thegirder.

The girder cross section is simple — itconsists of reinforced concrete edgebeams, 5 ft (1.5 m) deep by 3.5 ft (1 m)wide, and an 8 in. (200 mm) thick road-way slab. This slab is supported by 33in. (840 mm) deep rolled steel beams,framed into the concrete edge beams

and spaced 9 ft (2.75 m) apart.The girder face is hlunt. The stream-

lined, aerodynamic shape of the girderused earlier has been omitted as unnec-essary. The standard size, rolled steelcross beams are modified for the re-quired camber, with attachments to de-velop fixity at the concrete edge beams.Simplicity in arrangement for prefabri-cation of the precast elements was in-tended and achieved.

TowerThe hollow, sloping tower legs con-

tain an electric elevator for access to thecable anchorages. These legs terminateat the towerhead. The concrete tower-head is I-shaped and features a centralcore 6 ft (1.83 m) thick for receiving the62 cable anchorages and their compres-sion forces,

The cable anchorage part of the tow-erhead is 89 ft (27 m) high. The anchor-

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age area is protected from weather con-ditions with dark colored precast con-crete panels 3 1 in. (90 mm) thick.

Cable SystemBBR type cables with Hi-Am anchor-

ages were specified and used. These ca-bles consist of straight 6 mm wires en-cased in forged steel anchorage as-semhlies, covered with polyethylenepipes and filled with grout for corrosionprotection.

The cable sizes vary from 83 to 307wires each; their length varies from 200to 769 ft (61 to 233 in). The cables wereprefabricated to their prescribed Iengthand installed from top to bottom withforce adjustments at the bottom anchor-ages.

Both upper and lower stay cable an-chorages contain rigid steel pipes sur-rounding the part of the cable end inwhich neoprene dampers were installedto control potential cable vibrations.The use of these neoprene dampers hasproven to be very successful. For exam-ple, the stay cables used in the Pasco-Kennewick Bridge have the dampers atthe lower end only and the cables oc-casionally experience slight, barely per-ceptible oscillations. At East Hun-tington, cable oscillations seldom occurand are not easily perceptible.

Aerodynamic StabilitySuspended girder response to wind

has been studied extensively and theknowledge gained from such studies hasbeen beneficial for the proper design ofsuspension bridges. Lacking compar-able knowledge about cable stayedbridge girder behavior in wind, the sus-pension bridge criteria were used forthe cable stayed bridge girder design.

The presence of many cable stays,high longitudinal forces in the girder,and the effects of girder mass in con-crete bridges measurably enhance the

concrete cable stayed girder's dynamicstability. The Pasco-Kennewick Bridge,being the first of its kind, receivedstringent suspension bridge treatment.The Pasco-Kennewick girder has astreamlined, aerodynamic shape andsubsequent motion studies have re-vealed that the expected motions do notoccur or are not measurable.s

Conventional wind tunnel sectionmodel studies were carried out in ac-cordance with FHWA policy. 6 The testsection exhibited vortex induced oscil-lations of less than 2,5 percent of gravityfor 12 to 15 miles per hour (5.4 to 6.7rn/sec) wind speeds. Actual bridge mo-tion noted to date has been impercept-ible.

The girder is also safe against flutterinstability in an extremely strong wind.Aided by the stiff A-frame tower, the tor-sional to vertical oscillation frequencyratio is 3.0 at 2 percent critical damping.The potential flutter producing windspeed has been estimated at the 230miles per hour (103 rnlsec) level orhigher.

Other Design ParametersCritical elements for structural organ-

ization were:1, Steel cross beam framing into the

concrete edge beams, and managementof differential temperature stresses inthe region where the steel girders frameinto the edge beams, both during castingof the girder elements and in service.

2. Stress array distribution in thetower head core would have to with-stand all forces generated from the en-tire cable system. Critical were theupper cables because their forces arethe highest.

3. The areas where the girder stiffnessand tower stiffness change rapidly, forexample, at the cable stayed girder endsand at the ends of the tower legs.

To avoid concrete transitions withundue rapid stress rises or stress con-

PCI JOURNALJanuary-February 1987 25

Fig. 5. Aerial view of tower. Fig. 6. Closeup of towerhead beforeinstallation of cables.

centrations, local prestressing and lib-eral distribution of local mild steel re-inforcement have been provided at re-gions where large force and stiffnesstransitions Occur.

Construction

In order for the bridge constructionprocess (Figs. 3 to 12) to conclude withall design objectives accomplished, it isimperative that a high level of work-manship and quality control disciplinebe maintained. All operations must bethoroughly planned in advance and con-structors must adhere to such planswithout improvisation. The design en-gineer should guide the work sequenceand quality control procedures to ensurecompliance.

These principles were adhered toduring construction of the East Hun-tington Bridge. The concrete operationsprogram was developed beforehand andstrictly implemented. Due to the own-er's rigid guidelines pertaining to theminimum strength requirements of the

concrete, all concrete was made to10,000 psi (69 MPa) 28 day strength. Theconcrete mix had a water-cement ratio of0.30 and was produced in a speciallybuilt floating concrete plant equippedwith electronic moisture monitoring andbatching controls.

The cable stayed girder elementswere match cast in a specially built, longline casting yard near the bridge site,then barged and lifted by a 600 ton (544t) floating crane into position. Match castsurfaces were coated with epoxy andprestressed onto the previously erectedgirder parts. To control the stability ofthe tall tower on the narrow foundation,and to resist the effects of imbalance onthe long girder, temporary stability ca-bles were used during erection of thegirder.

AestheticsThe purpose of engineering design is

to organize the least complicated systempossible that will fully serve all objec-tives. If correctly done, an observer of

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Fig. 7. Towerhead with cables in place. Fig. 8. Closeup of towerhead afterinstallation of cables.

the East Huntington Bridge will per-ceive the purpose of the visible order,will accept its simplicity, and will sensethe latent power and strength of thestructure.

All three of the above are positive,gratifying perceptions that are easilymade. And, when positive feelings doresult, the work is termed aestheticallyacceptable, aesthetically correct orpleasing, and satisfying.

With regard to the overall organi-zation of the East Huntington Bridge,the observer notes that the river is wide,the tower is tall, the girder is slender,and the cables are white and thin. Thesystem is simple and graceful andstrong, all at the same time. This per-ception communicates a message and afeeling that great strength can be ob-tained, and much service received, froma simple arrangement. This emotionalacceptance of the whole structure is ac-claimed freely by the users of the com-pleted bridge; and this is the essence ofaesthetics in the work of a bridge en-gineer.

Concluding Remarks

The completed work, built on piersoriginally meant for a steel bridge, re-duced the expected project costs consi-derably. The main span material — con-crete — was made in the field to veryhigh strength requirements. The resultwas an overall reduction of the struc-ture's weight, increased durability, andthe availability of residual tensile stresscapability for accommodating incidentalstresses. In addition, the low water-cement ratio in the concrete markedlyreduced concerns about concrete creepand shrinkage.

Incorporation of structural steelmembers in the concrete girder resultedin simple workmanship, low girderweight and low project costs. It alsoproved that the hybridization of con-crete and steel components can be usedsuccessfully in concrete bridges. Fur-thermore, the concrete bridge systemincreased the original steel bridge'sfoundation loads by less than 20 per-cent, making foundation changes un-

PCI JOURNAL/January-February 1987 27

Fig. 9. Nearly completed East Huntington Bridge.

the East Huntington Bridge is capableof supporting a 1650 ft (500 m) or longermain span when used in a two tower,symmetrical configuration. This is pos-sible without altering member size.

The East Huntington Bridge was awinner in the 1985 PCI ProfessionalDesign Awards Program.

CreditsOwner: West Virginia Department of

Highways, sponsored by the FederalHighway Administration.

General Contractor: Melbourne Bros.,Inc., North Canton, Ohio. Stay cablesmanufactured by Shinko Wire, Japan.

Engineer for Project Design and Con-struction Control Guidance: ArvidGrant & Associates, Inc., ConsultingEngineers, Olympia, Washington.Arvid Grant, project concept and sys-tem; Conrad Bridges, detaileddesign;David Goodyear, construction control.

References

1. Grant, Arvid, "The Pasco-Kennewick In-tercity Bridge," PCI JOURNAL, V. 24, No.3, May-June 1979, pp. 90-109.

2. Bridges, Conrad P., and Coulter, CliffordS., "Geometry Control for IntercityBridge," PCI JOURNAL, V. 24, No. 3,May-June 1979, pp. 112-1225.

3. Grant, Arvid, "Pasco-Kennewick Bridge,The Longest Cable-Stayed Bridge inNorth America," Civil Engineering, V. 47,No. 8, August 1977.

4. Bridges, Conrad P., "Erection Control ofPasco-Kennewick Intercity Bridge,"Cable-Stayed Bridges, Structural Engi-neering Series, No, 4, Bridge Division,Federal Highway Administration,Washington, D.C.

5. Bampton, M. C. C., and Ramsdell, J. V.,"Dynamic Characteristics of the Pasco-Kennewick Cable-Stayed Bridges,"Fourth U.S. National Conference on WindEngineering and Research, BattellePacific Northeast Laboratories, Seattle,Washington, July, 1981.

Fig. 11. Roadway view of the EastHuntington Bridge.

Fig. 12. Finished view of East HuntingtonBridge at twilight.

6. Cermak, J. E., Bienkiewicz, B., andPeterka., J. A., "Wind Tunnel Study of theEast Huntington Bridge Concrete Alter-native," Colorado State University, FortCollins, Colorado, 1980.

PCI JOURNAUJanuary-February 1987 29