aspire spring08
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T H E C O N C R E T E B R I D G E M A G A Z I N E
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.aspirebridge.org
S P R I N G 2 0 0 8
Protecting Against & EvaluatingFIRE DAMAGE!
DES PLAINES RIVER VALLEY
BRIDGE ON I-355
Lemont, Illinois
MAROON CREEK BRIDGE
REPLACEMENT
State Highway 82, Aspen, Colorado
LOOP 340 BRIDGES
Waco, Texas
TAXIWAY SIERRA UNDERPASS
Sky Harbor Airport, Phoenix, Arizona
http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/http://www.aspirebridge.org/ -
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NEW configurations and licenses available to match the way you work!Please contact us for more information. (888) 793-5490 [email protected] www.bentley.com/LEA
ONE Central ApplicationLEAP Bridge acts as the central informationhub for your projects. Exchange data withAASHTOWares BRIDGEWare Database.Transfer important data with any LandXMLcompliant applications (MicroStation,GEOPAK, InRoads and more).
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2008 Bentley Systems, Incorporated. Bentley, the B logo, LEAP Bridge, CONBOX, CONSPAN, CONSPLICE, CONSYS, GEOMATH, and RC-PIER are either registered or unregistered trademarks or servicemarks of Bentley Systems, Incorporated or one of its direct or indirect wholly-owned subsidiaries. Other brands and product names are tr ademarks of their respective owners.
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ASPIRE, Spring 2008|
C O N T E N T S
FeaturesCH2M Hills Holistic Approach 8Combining design and construction services helpsfirm meet owners growing needs for speed andconstructibility.
Protecting Against Fire 18Concrete can help bridges resist a blazes high heatand return quickly to service.
Evaluating Fire Damage 24A Case Study.
Des Plaines River Valley Bridge on I-355 28Deep Spliced Girders Save Tollway $8 Million.
ASBIs First 20 Years and the Future 34
Maroon Creek Bridge Replacement 38
Loop 340 Bridges 44Preassembled Bridge Facilitates Overpass Construction.
Taxiway Sierra Underpass 48Aircraft Bridges Take Off.
Social Benefits of Sustainable Concrete Bridges
Photo:IllinoisStateTollHighwayAuthority.
Photo:P
arsons.
Photo: HDR Inc.Photo:TxDOT.
Photo:CH2MHill.
Ben
icia-MartinezBridge
Photo:CH2MHill.
DepartmentsEditorial 2
Reader Response 4
Concrete Calendar 6
PerspectiveSustainability, Social Benefits ofConcrete BridgesHow Green is Our Valley? 16
Aesthetics Commentary 42
Concrete Connections 52
Safety and Serviceability 53
FHWA 54
STATEConcrete Bridges in Arizona 58
COUNTYBoone County, Iowa 62
AASHTO LRFD Specifications 64
8
38
28
48
44
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Photo: Ted Lacey Photography. John S. Dick,Executive Editor
2|ASPIRE, Spring 2008
EDITORIAL
In this issue of ASPIRE, we continue our year-long program to define sustainable issues in
bridge design and construction. On page 16, KevinEisenbeis, a Principal with Harrington & CortelyouInc., Kansas City, Missouri, outlines the societalaspects of sustainability: life safety, accelerated bridgeconstruction, context sensitive designs, long service life,and aesthetics.
One life-safety issue impacting bridges is their fireresistance. Fire is an ever-present concern of all owner
agencies. As more and more flammable materials arecarried over the highway system, fires will continue tooccur with increased frequency.
Accordingly, this issue contains two articles on firethat should be of interest to owners and designers alike.In the first, on page 18, we report on eight concretebridge fire events that occurred in recent years. Thebridges covered illustrate that even after exposure to firesof various intensities, concrete can remain in service,circumventing long-term closures or long-distancedetours. The primary beneficiary of this concrete-bridgecapability is the traveling public, who can continueto use these important arteries while owners consideralternatives for repair or replacement.
That raises a frequent question addressed byour second fire-resistance article, on page 24: Howcan fire-damaged concrete be evaluated? From thePacific Northwest, the Washington State Departmentof Transportation (WSDOT) provides details of theirinvestigation into a 3000 F bridge inferno. RichardStoddard, Bridge Design Engineer with the Bridgesand Structures Office of WSDOT, offers importantinformation about what they did when tragedy struck.Without precedent, they quickly established definitiveanalytical methods and determined that the bridge
could be reopened to traffic while more long-termsolutions were sought. A more complete report on theirwork is available atwww.aspirebridge.org/resources/.Additional photos are also available on the websit efollowing the article.
Further expanding on the sustainability theme, M.Myint Lwin, Director of the Office of Bridge Technologyat the Federal Highway Administration, describes theFHWA green programs now underway (see page 54).FHWA is actively participating in the Green Highways
Partnership, a voluntary public/private initiative.
Sustainable Bridge Design Awards
Also in the sustainable-bridge area are two awardpro grams announced in thi s iss ue. The Precas t/Prestressed Concrete Institute (PCI) is soliciting entriesfor its Bridge Design Awards program (see the noticeon page 43). One category available to designers is theSustainability Award. The purpose is to recognize theconstruction of responsible, innovative designs that aresensitive to the environment while meeting the needsof the public and the owner. Deadline for entries isMay 23, 2008. Details are available on the PCI website(www.pci.org, select News and Events).
Also, the Portland Cement Associa tion (PCA) hascreated the Sustainable Leadership Awards. PCAdeveloped these awards to honor public officials whoutilize concrete and other cement-based productsin public works projects such as highways, streets,bridges, dams, pipe, or water systems that are energyefficient and beneficial to the community. Be sureto notify your colleagues about this opportunity foragency recognition. Deadline for entries is May 30,2008. Details are available at www. cement .org/sustainableleadership/.
Executive Editor:John S. Dick
Managing Technical Editor:Dr. Henry G.Russell
Managing Editor:Craig A. Shutt
Editorial Staff:Daniel C. Brown, Roy Diez,Wayne A. Endicott
Editorial Administration:James O. Ahtes Inc.
Art Director:Mark Leader, Leader GraphicDesign Inc.
Layout Design:Marcia Bending, LeaderGraphic Design Inc.
Electronic Production:Chris Bakker,Jim Henson, Leader Graphic Design Inc.
Ad Sales:Jim OestmannPhone: (847) 577-8980 Cell: (847) 924-5497 Fax: (847) [email protected]
Reprint Sales:Mark Leader(847) 564-5409e-mail: [email protected]
Publisher:Precast/Prestressed Concrete Institute,
James G. Toscas, President
Editorial Advisory Board:David N. Bilow,Portland Cement Association(PCA)
John S. Dick,Precast/Prestressed ConcreteInstitute (PCI)Clifford L. Freyermuth,American Segmental
Bridge Institute (ASBI)Theodore L. Neff,Post-Tensioning Institute (PTI)Dr. Henry G. Russell,Managing Technical Editor
POSTMASTER:Send address changestoASPIRE, 209 W. Jackson Blvd., Suite 500,Chicago, IL 60606-9887. Standard postage paidat Chicago, IL, and additional mailing offices.
ASPIRE(Vol. 2, No. 2), ISSN1935-2093ispublished quarterly by the Precast/PrestressedConcrete Institute, 209 W. Jackson Blvd., Suite500, Chicago, IL 60606-6938.
Copyright 2008, Precast/Prestressed ConcreteInstitute.
If you have a project to be considered forASPIRE,send information toASPIRE,209 W. Jackson Blvd., Suite 500,Chicago, IL 60606-9887
phone: (312) 786-0300www.aspirebridge.orge-mail: [email protected]
Cover: Puyallup River Bridge (main photo)Wash.See Protecting Against & Evaluating
Fire Damage articles beginning onpage 18 for additional credits.
Bridge Sustainability, Part Two:Societal Issues
Log on NOW at www.aspirebridge.organd take theASPIREReader Survey.
Precast/PrestressedConcrete Institute
Post-TensioningInstitute
Portland CementAssociation
American Coal AshAssociation
Wire ReinforcementInstitute
Expanded Shale Clayand Slate Institute
National Ready MixedConcrete Association
Silica FumeAssociation
1American Segmental
Bridge Institute
mailto:[email protected]:[email protected]:[email protected]://www.aspirebridge.org/http://www.pci.org/http://www.pci.org/http://www.post-tensioning.org/http://www.post-tensioning.org/http://www.cement.org/bridges/http://www.cement.org/bridges/http://www.acaa-usa.org/http://www.acaa-usa.org/http://wirereinforcementinstitute.org/http://wirereinforcementinstitute.org/http://www.escsi.org/http://www.escsi.org/http://www.nrmca.org/http://www.nrmca.org/http://www.silicafume.org/http://www.silicafume.org/http://www.asbi-assoc.org/http://www.asbi-assoc.org/http://www.asbi-assoc.org/http://www.asbi-assoc.org/http://www.silicafume.org/http://www.nrmca.org/http://www.escsi.org/http://wirereinforcementinstitute.org/http://www.acaa-usa.org/http://www.cement.org/bridges/http://www.post-tensioning.org/http://www.pci.org/http://www.aspirebridge.org/mailto:[email protected]:[email protected]:[email protected] -
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AN EQUAL OPPORTUNITY EMPLOYER
Pennsylvania Turnpike Commissioncontinuestheir capital plan with the replacement of theI-76 bridge at Oakmont, Pennsylvania, across theAllegheny River. Pennsylvania's first cast-in-placeconcrete segmental bridge was designed by FIGGand is being built by Walsh Group. Twin 2,350' longstructures are being constructed from above topreserve and maintain vehicular, river and railtraffic below. Spans of 285/380/380/444/532/329cross the river and Fourteen Mile Island.The bridge is on schedule to open in 2010.
Long Span Bridge Landmark
Twin wall piers are cast with an inlaid stone pattern. The completed superstructure box girder pier tabl
is revealed with removal of formwork (02.18.08).
The curved rectangular piers reflect the curved
shape of the superstructure.
If you share our passion forcreating bridge landmarks, join theFIGGTeam. For an exciting careeras a Bridge Design Engineer, CADDDesigner, Construction SiteEngineer or Inspector, pleasecontact us at 1.800.358.FIGG (3444)or www.figgbridge.com.
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THE CONCRETE BRIDGE MA GA ZINE
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WINTER2008
TorreyPinesRoadBridgeSanDiego,California
ERNESTF. LYONSBRIDGEREPLACEMENT
Stuart,Florida
ST.ANTHONYFALLS(I-35W)BRIDGE
Minneapolis,MinnesotaFIFTHSTREETPEDESTRIANPLAZABRIDGE
Atlanta, Georgia
DEVILSSLIDEBRIDGEPacifica, California
DAGGETTROADBRIDGEStockton, California
4|ASPIRE, Spring 2008
READER RESPONSE
Dr. Ah lborns
Persp ect ive on Sus tainab il ity
correctly champions the role of education in the
realization of a sustainable future. Innovative
so lut ion s are defin ite ly needed; however,
none of the three tenets of sustain-ability
(environmental, social and economic) deserve
relegation to a diminutive role. Will merely
shif ting the focus of engineer ing education
to social and economic tenets rather than
environment issues solve our problems? Another
question concerns whether an economic cost-benefit analysis accurately reflects environmental
values. Social and economic well-being of our
species, as we know life, depends on a healthy,
sustainable environment . . . Engineering
education must not restrict itself to the free-body
diagram boundaries within an engineering
project. It may not be appropriate to only
examine efficiencies of a bridge joint when
we need to holi stically examine the entire
transportation system and its relationship to our
other life-support systems.
Roger PatockaEstherville, Iowa
[Editors Note: Mr. Patocka raises significantissues concerning our standard design practice fortransportation systems and our focus toward theenvironment. Individually, we may not have directcontrol over long-range solutions needed to affectchange for the planet, but we do have choicesin our design solutions and the materials that
we select on a daily basis that will have positiveimpacts. This is one of the ultimate challenges ofsustainability, changing our design philosophies
to truly think holistically. See the article on page16 that provides another installment in our goalof environmental awareness.]
Congratulations on a great inaugural year
and your vision that has been realized. This
is a great magazine that allows the bridge
professional to review the state-of the-art of
concrete bridges in one publication. One of
the few that I put in my briefcase to read
whenever I have a moment.
Jon Grafton
President, Pomeroy CorporationPerris, Calif.
The number of deficient bridges in most
states . . . makes the focus of ASPIRE mag-
azine very timely. ASPIRE gives us a good tool
to learn from each other: about what works,
what looks good, and what can get the job
done with the least impact on the traveling
public. Please keep it going!
Hank BonstedtExecutive DirectorCentral Atlantic Bridge Associates
Allentown, Pa.
First of all, I wanted to congratulate you
on the quality of ASPIRE magazine. I thought
the first issue was great and it just seems to
get better with every issue! The latest issue of
Aspire has PB as its company highlight. Im
especially interested in this issue because Ive
recently relocated to PBs Honolulu office
and the cover shot is of Keehi Interchange justdown the street from us.
Taka KimuraPrincipal Engineer, PB
Honolulu, Hawaii
Innovative, Proven and Durable.BRIDGE POST-TENSIONING SYSTEMS:
www.vsl.net 888.489.2687
Owners and design teams rely on VSL to
provide innovative technology and proven
systems to maximize the durability of
transportation structures. A world leader in
post-tensioning, VSL has evolved into a multi-
disciplined bridge partner capable of providing
contractors and engineers with design support,
as well as construction systems and services
for precast segmental, cast-in-place and stay
cable bridges.
SYSTEMS
BONDED MULTISTRAND
VSLAB+BONDED SLABS
STAY CABLES
VIBRATION DAMPING
SERVICES
SYSTEM INSTALLATION DESIGN SUPPORT
HEAVY LIFTING
REPAIR & STRENGTHENING
EQUIPMENT RENTAL
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ASPIRE, Spring 2008|
photo courtesy of Kiewit Pacific Company
Future Technology forConcrete Segmental Bridges
NOVEMBER 17-19, 2008Fairmont Hotel, San Francisco, CA
PROGRAM INFORMATIONAVAILABLE May 1, 2008
www.asbi-assoc.org/news/symposium/
i i
Photos courtesy of Caltrans
Two Harrison Street, Suite 500, San Francisco, California 94105
tel: 415.291.3700 |fax: 415.433.0807 |www.tylin.com
New Benicia-
Martinez BridgeBenicia, California
Built to withstand earthquakes
in a high-seismic zone, thenew five-lane, 7,400-ft.
Benicia-Martinez Bridge is
a lifeline structure for San
Francisco Bay Area residents,
a challenging designation for
a bridge with such long span
lengths. To learn more, visit
www.tylin.com/ads.
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Photo:TedLaceyPhotography.
6|ASPIRE, Spring 2008
CONCRETE CALENDAR 2008
April 14-15ASBI Grouting Certification TrainingJ.J. Pickle Research Center, University of Texas at Austin, Austin, Texas
April 24-27PCI Annual Committee DaysIncludes meeting of PCI Bridge Committee and AASHTO Technical Committee on Concrete Design (T-10)Westin Hotel. Chicago, Ill.
May 4-6PTI Technical Conference & ExhibitionHyatt Regency St. Louis, St. Louis, Mo.
May 4-7NCBC-FHWA 2008 Concrete Bridge ConferenceHyatt Regency St. Louis, St. Louis, Mo.
May 5-10PCI Quality Control & Assurance Personnel Training & Certification Schools
Embassy Suites Hotel - Nashville Airport, Nashville, Tenn.
May 18-22AASHTO Subcommittee on Bridges and Structures MeatingHilton Omaha and Qwest Center, Omaha, Neb.
May 20-22NRMCA Concrete Technology Forum: Focus on Sustainable DevelopmentMarriott Denver Tech Center, Denver, Colo.
June 2-4International Bridge Conference & ExhibitionPittsburgh Convention Center, Pittsburgh, Pa.
July 27-30
Sixth National Seismic Conference on Bridges & HighwaysOrganized by the Federal Highway Administration (FHWA), the Transportation Research Board (TRB),the South Carolina Department of Transportation (SCDOT) and MCEER, University at Buffalo, N.Y.Francis Marion Hotel, Charleston, S.C.
July 28-29ASBI Seminar on Segmental Construction PracticesHilton Sacramento West and Arden West, Sacramento, Calif.
August 4-6PCI Quality Control & Assurance Personnel Training & Certification SchoolsEmbassy Suites Hotel Nashville Airport, Nashville, Tenn.
October 6-8PCI-FHWA National Bridge Conference
Rosen Shingle Creek Resort, Orlando, Fla.
November 2-6ACI Fall ConventionRenaissance Grand & Americas Center, St. Louis, Mo.
November 3-8PCI Quality Control & Assurance Personnel Training & Certification SchoolsEmbassy Suites Hotel Nashville Airport, Nashville, Tenn.
November 17-19ASBI International Symposium on Concrete Segmental BridgesFairmont Hotel, San Francisco, Calif.
M. Myint Lwinis Director
of the FHWA Office of Bridge
Technology in Washington,
D.C. He is responsible for the
National Highway Bridge Program direction, policy, andguidance, including bridge technology development,
deployment and education, and the National Bridge
Inventory and Inspection Standards.
CONTRIBUTING AUTHORS
Dr. Dennis R. Mertzis
Professor of Civil Engineering
at the University of Delaware.
Formerly with Modjeski and
Masters, Inc. when theLRFD Specificationswere first written,
he has continued to be actively involved in their development.
Kevin Eisenbeisis a
Principal with Harrington &
Cortelyou Inc., Kansas City,
Mo. His responsibilities include
management of major highway
and railway projects including
the design of eight Missouri River
bridges.
Dr. Henry G. Russellis an engineering consultant,
who has been involved with the applications of concrete in
bridges for over 35 years and has published many papers
on the applications of high performance concrete.
MANAGING
TECHNICAL EDITOR
James M. Barkerwas Vice President with HNTB Corp.
and is currently teaching at the Civil Engineering School
of Purdue University.
Frederick Gottemoelleris
an engineer and architect, who
specializes in the aesthetic aspects
of bridges and highways. He is
the author ofBridgescape, a
reference book on aesthetics and was Deputy Administrator of
the Maryland State Highway Administration.
For links to websites, email addresses,or telephone numbers for these events,
go to www.aspirebridge.org.
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High above the Carquinez Straight, the new Benicia-Martinez Bridge now carries five lanes
of northbound traffic, significantly reducing daily traffic congestion for the 100,000 vehicles
using I-680. CH2M HILL, in a joint venture with TY Lin International, used lightweight
concrete and a cast-in-place method in constructing the 1.6-mile-long bridge.
CH2M HILL applies innovative technology to complete complex projects. Were a
leading design-build firm with more than 60 years of design, construction, and program
management expertise. CH2M HILL can help you take your next concrete infrastructure
project to new heights.
Solutions Without Boundariesch2mhill.com/transportation
Taking concrete innovations to new heights
CH2M HILLs recentpreservation of the historic
Rainbow Bridge in Idaho
was recognized as the
International Concrete Repair
Institutes 2007 Project of
the Year.
TB022008003MKT
2008 CH2M HILL
http://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportationhttp://www.ch2mhill.com/transportation -
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FOCUS
CH2M Hills engineering, construction, andoperations capabilities have served a largevariety of clients throughout the worldsince the firms founding in 1946. Thoseskills are being integrated closer than evertoday, especially as the company meetsa wider array of needs from owners ofbridges and other transportation structures
throughout the United States.
We are a full-service provider, explainsJoe Showers, Chief Bridge Engineer.We have the depth and breadth ofcapabilities under one roof to provideflexibility to the client as we participatein a project. These range from theenvironmental document and planningstages through the final design stageand include being a designer-constructor.We span the length of the project fromconcept to completion.
Design-build is a delivery method that
we use frequently, and we consciouslydeveloped consulting and constructionmethods to allow it to happen. Moreowners are growing comfortable withthe design-build format, because theyrecognize that the benefits can helpachieve their goals. Design-build has beenused with buildings for some time, and
its moving into the transportation fieldtoday, because owners are being drivenby pressure on schedules in particular.
The design-build format can condensethe time needed for the project, asconstruction can commence beforeall the design is completed. That notonly saves time but can save money,shorten labor schedules, and reduceuser costs incurred through detours andcongestion delays. A cost savings oftenis produced, but design-build definitelycreates a savings in the schedule, which
is the critical component in most cases.
CH2M HILLS
Combining design
and construction
services helps firm
meet owners
growing needsfor speed and
constructibility
by Craig A. Shutt
HOLISTICAPPROACH
8|ASPIRE, Spring 2008
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Some of the 72-in.-deep precast,
prestressed concrete I-girders are
delivered and set for the I-794
bridges at the east end of the
Marquette Interchange project
in Milwaukee. The project was
designed for the Wisconsin
Department of Transportation
by Milwaukee Transportation
Partners, a joint venture of
CH2M Hill and HNTB.
All photos: CH2M Hill.
The Kathleen Road Bridge
over I-4 in Florida was created
under a design-build approach
and consists of a cast-in-place
concrete deck, pretensioned
concrete beams, cast-in-place
concrete piers, prestressed
concrete piles, and concrete
panels for the mechanically
stabilized embankment walls.
The structure replaced a smaller
1958 design.
Designs Are MoreComplicatedOwners are looking for new ideasto aid designs in every way possible,because bridge construction hasbecome more complicated in the past20 years, he adds. Owners are very
cost-conscious today, due to increasesin costs for materials and labor. Withcost escalations as high as 10 percentper year, it can be difficult to createbudget estimates for bridges that willbe constructed well after the design andmaterial choices are finalized.
Design-build formats in particularbring design engineers and constructorstogether on the same team, workingtoward a common goal, as opposed tobeing adversaries, he says. More oftentoday, the engineer and contractor work
closely together rather than separately.
The functions used to be fairly splitapart, but now owners understand thevalue of marrying the two closer to aidcommunication and input.
We have to look at the total projectfor savings and constructibility, and
the emphasis has become the totalproject cost, not just savings in designor construction. Our designs definitelyfocus on creating the most cost-effectivebridge to be constructed, not justdesigned.
Traffic Control KeyIngredientOwners also are putting an emphasison traffic control, a result of projectsbecoming more congested as infra-
structure expands outward from citiesand becomes more complex. There arefew green-field sites today, Showerssays. Many of our projects involverehabilitation and widening of corridorsunder traffic, and we have to deal withthose challenges. They definitely areaffecting how we plan projects.
An example of the attention paid tothis factor is the Marquette Interchangeupgrade in Milwaukee. The $1-billionproject encompasses 12 miles of urban
freeways, including the design of 50ramps and construction of more than180 bridge structures. It also featuresfive levels of roadways and 300,000vehicles per day. The project, a jointventure of CH2M Hill and HNTB,features 72-in.-deep precast, prestressedconcrete I-girders for the bridges.
The four-year reconstruction was thelargest and most complex transportationproject ever undertaken in Wisconsin,Showers says. As a result, Publicperception of impacts and alternative
routes around the construction were
More often today, the engineer and contractorwork closely together rather than separately.
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As the largest highway-
construction project in the
Colorado Springs history, the$150-million COSMIX project
involved reconstruction of 16
bridges and widening four more.
Rockrimmon Constructors, a
CH2M Hill-led joint venture with
SEMA Construction, also provided
design-build services to expand
12 miles of highway capacity
and reconfigure two major
interchanges.
identified as extremely importantto the overall projects success. TheWisconsin Department of Transportationcommitted to keeping two lanes open ineach direction during construction.
To achieve that, CH2M Hill developed a
detailed schedule to clarify ramp and laneclosure times and locations. In additionto creating disincentives for missingthe schedule, the team also introduceda lane rental program, which gavecontractors an allotment of hours in whichto close freeway and ramp lanes withoutdisincentives. The lane-rental programwas an effective tool to reduce unneededlane closures and minimize disruptions tothe public. The team also found pathsfor temporary roadways to pass underexisting structures through the core of theinterchange.
Aggress ive communicat ion withbusinesses about detours also hasbecome commonplace on projects,Showers says. That was a key element in
the success of the $150-million ColoradoSprings Metro Interstate Expansion(COSMIX) project, which reconstructed16 concrete bridges and widenedanother four. CH2M Hill created a jointventure with SEMA Construction toprovide design-build services.
Those services included weekly meetingswith local business owners, as well asmaps and signage placed along theroutes to ensure changes were wellknown. More than 20 informal andformal town-hall meetings were heldduring the projects course, which usedmore than 300,000 cu yd of concrete torebuild I-25 through the metro area.
Durability Is StressedDurability also has come to the fore,
as owners look to decrease costsand create added safety. Ownersare focusing more on life-cycle coststoday and understand that its worthspending more upfront, because its agood investment if you dont have to
Owners are more willing to spend anotherdollar today to save $10 down the road.
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Working with the Idaho Transportation
Department, CH2M Hill strengthened
and restored the concrete-arched
Rainbow Bridge between Boise and
Cascade in Idaho. Key elements
included replacing ornate concrete
bridge rails, repairing corrosion-
damaged stringers, and repairing andreplacing corrosion-damaged columns.
Sharing the WealthCH2M Hill opened its doors in Corvallis,Oregon, in January 1946 as a partnershipamong three Oregon State College
engineering graduates and one of theirprofessors: Holly Cornell, T. Burke Hayes,James Howland, and Fred Merryfield. Some25 years later, the company merged withClair H. Hill & Associates to create CH2M Hill.
The founders concepts were simple butunusual: Grow the company by solvingclients problems, hire creative people tofind new approaches to those challenges,and share the benefits of the companyssuccess with them. The employees own thecompany through a stock-sharing program.
The company has won a number of awardsfor being employee-friendly. For instance,it was named one of Fortunemagazines100 Best Companies to Work For in 2006,one of Denvers Best Places to Work bythe Denver Business Journal, and one of theTop 50 Companies to Work For byWomanEngineermagazine.
By the end of the 1960s, the companyhad achieved revenues of $6.2 million,generated by 310 employees. The firmgained momentum with the 1971 Hilladdition and publicity from their partnershipon a ground-breaking wastewater treatmentfacility. One decade later, the companyhad revenues of $95 million and 1800employees.
Ralph Peterson was elected president in1991, ushering in a period of rapid growthand diversification. By the mid 1990s, CH2MHills 6000 employees produced revenuesclose to $1 billion. In 2006, the companyreported revenues of $5 billion achievedwith 23,000 employees from activities in 31
countries.
spend money on maintenance later on.They realize the key is total costs, notnecessarily just initial costs, and theyremore willing to spend another dollartoday to save $10 down the road.
Current specifications for a 75-yearlife contain the rules of the road, henotes, but some bridge owners areasking us to design for service lives of100 to 150 years. European engineersalready are evaluating ways to createsuch service lives routinely and aredeveloping models for it. Well seesome of that here in the coming years.
Likewise, sustainabil ity is gainingground, although Showers notes thatit hasnt become as major a concern in
America for bridges as it is in Europealready. Its growing in interest here,certainly. Energy costs are becoming akey aspect of designing bridges, andthe projects carbon footprint is beingdiscussed more.
Emphasizing ContextSensitivityAlong with sustainability is the need forcontext-sensitive solutions (CSS), whichCH2M Hill emphasizes in its designs.The company literally wrote the bookon this concept, as its staff served asprimary authors on National CooperativeHighway Research Program Report480: A Guide to Best Practi ces forAchieving Context Sensi tive Solut ions.CSS is an emerging trend andrequirement in the planning and design
of highways, and CH2M Hill has beenat the forefront, says Showers. Thegoal is to bring clients, stakeholders,agencies, and the public together inthe earliest phases of projects to
achieve sustainable solutions sensitiveto the project context. This approachaddresses safety, mobility, aesthetics,and other community values priorto design being finalized rather thanreacting to issues later in the process.This need has been driven by thepublic, he notes. People are becomingmore sensitive to the infrastructure andthe public involvement in designinghighway and railroad bridges in theircommunities. He likens it to the early1900s City Beautiful movement, whenemphasis was put on a citys physicalstate and how it could be improved.That urban-architecture movementfound its way into bridge designs, and asimilar movement seems to be underwaytoday.
Recreating bridges that have becomelocal landmarks poses challenges,Showers adds. To make an exactreplica of a 100-year-old bridge is toughtoday, because we dont build like thatanymore. If we can create a designthat harmonizes with that style, newtechnologies and advances in concretematerials give us far more capabilitiesfor achieving a high-quality, functional,and still complementary design.
An example can be seen in the RainbowBridge project, in which a 1933 concrete
CH2M Hill has been at the forefront of using
context-sensitive solutions to meet challenges.
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CH2M Hill supplied design-
build services for the new
I-5/41st Street Interchange
(at center) and a new flyover
bridge (far left) that replaced
an outdated left lane exit
in Everett, Washington. The
project included the widening
of about 10 miles of highway
and rebuilding bridges and
interchanges.
treat concrete as a highly engineeredmaterial, and thats an evolving change.These advances affect what can beaccomplished with bridge engineering,and thats really exciting. The changeshave been particularly notable in theprecast concrete field, with techniquesachieved with formliners, coloring, andother aesthetic options. There really area lot of new options being created.
Its up to designers to stay up to dateand incorporate new ideas whenapplicable, he stresses. Designersare gaining awareness, and theyreasking questions about what can beaccomplished. For that reason, CH2MHill works closely with concrete suppliersearly in the design process. We dontwant to overspecify materials, so wework closely with concrete producers,and theyre very constructive with helpat the concept level. And since we alsoare contractors, we can integrate theideas throughout the process.
The new concepts are expanding
concrete applications in new directions,
spandrel-arch bridge over the PayetteRiver between Boise and Cascade, Idaho,was rehabilitated. CH2M Hill providedboth design and construction servicesfor the $2.9-million project, whichinvolved reconstruction of corrosion-damaged deck-stringer ends and repairof columns, piers, and arches. Existingdecorative bridge rails also were replacedwith an identical railing. Throughout thedesign, the original historic fabric of thebridge was retained whenever possible.
Concrete Helps MeetChallengesConcrete materials can help meet anumber of the challenges presented bythese trendsand that, too, has beena trend for some time, he states. Theindustry has been headed toward moreconcrete designs for the past 30 or 40years. Earlier, virtually every interstateoverpass, especially spans of more than
100 ft, was constructed with steel girders.
Everything is changed now. Wereseeing precast, prestressed concrete usedmuch more often, with box girder spansas short as 80 ft. At the same time,some prestressed spliced girders areextending to 350-ft-long spans. Spliced-girders and segmental technology haveexpanded the use of concrete in bridges,and post-tensioning is more widespreadthan ever.
The concrete industry has changeddramatically in recent years, he adds,increasing its capabilities significantly.In the 1980s and 1990s, many of theadvances in bridge engineering couldbe attributed to computer software thatallowed designs to be modeled and betterforecasts and calculations to be created.But in the last 5 to 10 years, the changesweve seen have been due to changes inmaterials and better performance, andthat includes concrete.
High performance concrete is a key
example. Designers are starting to
Designers are starting to treat concreteas a highly engineered material.
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The new multiple-span Benicia-
Martinez Bridge traverses the
Carquinez Strait between the
City of Benicia in Solano County
and the City of Martinez in
Contra Costa County, California.
The cast-in-place, segmental
bridge is built to be a lifeline
structure, remaining open to
emergency traffic after a majorearthquake.
he adds. For instance, the firm hasworked with the Colorado Departmentof Transportation on one of seven bridgesthe department has developed using acurved, spliced-girder system. Theyvepioneered this design and led the way,which is really an interesting approach.Owners are definitely sold on concreteconcepts and are leading its use.
Lightweight ConcreteEvolvingConcrete mixtures that have led to more
lightweight concrete also are changingdesign concepts, he says. Lightweightconcrete is fast becoming a standard,and it has a tremendous influence ondesign.
An example can be seen in the companyswork in a joint venture with T.Y. LinInternational on the Benicia-MartinezBridge in California. The project usedsand-lightweight prestressed concretebox girders constructed primarily by thesegmental, balanced cantilever, cast-in-
place construction method. The sand-
lightweight concrete uses normal weightsand and lightweight coarse aggregate toproduce concrete that is lower in densitythan normal weight concrete. (For moreon this project, see the Summer 2007issue ofASPIRE.)
We needed to use concrete that waslightweight but that also offered otherproperties related to modulus of elasticityand creep, he explains. We stretchedthe capabilities in that design, and that ishappening more often all the time.
The design for the new 3175-ft-longconcrete crossing of the Fraser Rivernear Vancouver, British Columbia,Canada, features a much lower profiledue to the concrete material and a newfoundation design, which uses large-diameter bored piles to provide cost-effective construction in the deep layersof soft silt. The project also features anemphasis on aesthetics, using decorativeeagles as a recurring theme on bridgetowers and other locations.
Self-consolidating concrete also is being
used more often, most usually to aidcontractors in speeding constructionrather than for design purposes.Showers notes. He also has great hopesfor a variety of new reinforcementmaterials, such as fiber reinforcedplastics or carbon fibers.
A number of states have createddemonstration projects with thesematerials, and there is some work beingdone in Europe, he says. I haventseen a massive breakthrough yet, butthere could be one in the next fewyears. It would be ideal if the materialcould be put into slabs and wouldntcorrode. An indefinite service life wouldbe the Holy Grail.
As concrete producers work with CH2MHill toward that goal, the firm willcontinue to improve on its own designand construction processes, as wellas their integration, to help cut costsand create designs that meet the morediverse, specialized, and challengingneeds of all types of bridge clients.
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mailto:[email protected]://www.newcrete.com/mailto:[email protected]://www.jerseyprecast.com/mailto:[email protected]://www.spibeams.com/mailto:[email protected]://www.usacivil.skanska.com/http://www.caba-bridges.org/http://www.pcap.org/ -
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DYWIDAG-SYSTEMS INTERNATIONAL
HQ America Business Unit 525 Wanaque Avenue 4732 Stone Drive, Suite BPost-Tensioning & Reinforcement Pompton Lakes, NJ 07042, USA Tucker, GA 30084, USA
DYWIDAG-SYSTEMS Phone (973) 831-6560 Phone (770) 491-3790INTERNATIONAL USA INC. 320 Marmon Drive320 Marmon Drive Bolingbrook, IL 60440, USA 1801 N. Peyco Drive 2154 South StreetBolingbrook, IL 60440, USA Phone (630) 739-1100 Arlington, TX 76001-6704, USA Long Beach, CA 90805, USA Phone (630) 739-1100 Phone (817) 465-3333 Phone (562) 531-6161Fax (630) 972-9604E-mail: [email protected] www.dsiamerica.com
DYWIDAGPost-Tensioning Systems
Multistrand Post-Tensioning Systems
Bar Post-Tensioning Systems
DYNA Bond Stay Cable Systems
DYNA Grip Stay Cable Systems
Engineering
Construction Methods
Stay Cable Testing
Supply and Installation
ASPIRE, Spring 2008|1
Post-tensioning is being utilized on bridges in increasingly
varied ways, including cable stays for long-span applications,
segmental construction, bridge decks, strengthening, and on
spliced girders to extend the capabilities of precast elements.Post-tensioning offers some unique advantages that have lead
to rapid growth in its usage around the world.
Post-tensioned bridges have performed extremely well, but
reliability and performance are dependent on quality construc-
tion and good design. Education and training is one of PTIs
strategic goals. PTIs initiatives to assist designers and to help
assure a high quality workforce, include the following:
Bonded Post-Tensioning Certification
This 3-day training workshop is a comprehensive course on allaspects of bonded post-tensioning installation. It is intended for
construction personnel, inspectors, and construction manag-
ers. Attendees are certified following successful completion of
the training and subsequent examination. The next course is
planned for May 28-30, 2008, in Gainesville, Fla.
2008 PTI Technical Conference
The 2008 conference will be held May 4-6, 2008, in St. Louis,
Mo., and will feature technical sessions, committee meetings,
and PTIs 2008 Design Awards. It will be held jointly with theNCBCs Concrete Bridge ConferencePTI registrants can
attend all the bridge sessions.
Design Guides
The updated 5th Edition of PTIsStay Cable
Recommendationsis now available. In addition, PTIs
Bridge Committee is working on two design guides: 1) update
of PT Bridge Manual, and 2) Guide for PT Bridge Decks. Post-
tensioned bridge decks offer potential benefits such as reduced
cracking and improved durability, lighter superstructures, and
fewer girders.
For more information, contact PTI or visit our website at
www.post-tensioning.org.
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Rehabilitation of the Benton Boulevard
Bridge in Kansas City, Mo., allowed
preservation of an existing arch bridge
originally constructed in 1923.
Photo: Harrington & Cortelyou Inc.
16|ASPIRE, Spring 2008
PERSPECTIVE
Is sustainability merely a fad or aconcept whose time has come? At everyturn, we are exposed to print media,industry dialog, political stumping, andeven Hollywood celebrities promotingsustainability and the value of goinggreen. What is this all about, and howdoes the concrete bridge industry relate?And perhaps of greater significance, whyshould we care?
This issue of ASPIRE focuses on thesocial benefits of sustainable concretebridges. Social benefits, includinglife-safety issues, accelerated bridgeconstruction, context-sensitive designs,and aesthetics are just one aspect of theoverall theme of sustainable design as itrelates to highway bridges. Future issuesof ASPIRE will delve into the economicand ecologic aspects of sustainableconcrete bridges.
In this article, we will examine the social
benefits of sustainable concrete bridgesand how we can balance the impact ofour choices on society.
What is a SustainableStructure?For a better understanding of the subject,some definitions are in order. To thecasual observer, a sustainable structurewill last a long time and have minimalnegative impact on our environment.However, to the environmental advocate,
sustainability connotes a much deeperintent. To be truly sustainable, all aspectsassociated with a structure includingdesign, location, materials utilized,
construction techniques, maintenance,impact on the environment, overallenergy consumption, and effect onfuture generations must be considered.All elements should be coordinatedin a manner to benefit society. Theconsequences of our decisions now mayaffect our childrens future. To put itanother way, a sustainable bridge designaccomplishes our needs now withoutcompromising the ability of futuregenerations to meet their own needs.
Much of the concern in the field ofgoing green relates to carbon emissionsin the atmosphere. A reported three-fold increase in carbon dioxide in theatmosphere since 1977 prompts theglobal warming concern. One aspectof sustainability is the minimizationor elimination of carbon emissions toreduce the portion of climate changethat may be caused by this phenomenon.Locating bridges where drive times andtravel distances are minimized can reduceoverall carbon emissions from vehicles.
Social Benefits ofSustainable ConcreteBridgesSociety is the benefactor when ourindustry provides safe, long-term, dur-able structures. Even more so wheneconomical, attractive, and low-main-tenance describes our bridge. Soundfamiliar? Additional benefits occur whenconstruction minimizes site disruption,environmental impact, and trafficcongestion, again, all common benefitsinherent to current bridge construction.
Lets look at various social benefits ofconcrete bridges as they relate tosustainability.
Life SafetyConcrete bridges, with their typicallyredundant structural systems, are safebridges. The excellent fire and seismicresistance characteristics of thesestructures further ensures the public well-being. In seismic zones, confinementand corresponding ductile behavior inplastic hinge regions provides for minimalearthquake damage, low repair costs, andimmediate post-earthquake use. Withaccelerated bridge construction, rapidreplacement of other bridges that may
have been damaged is also beneficial.Concrete bridges also demonstrateoutstanding performance when exposedto fire as illustrated by other articles inthis issue. The necessity of safe bridges isfundamental to our industry.
Accelerated BridgeConstructionPrecast components al low rapidconstruction of bridges to occur. Withthe advancement of rapid constructiontechniques, construction time previously
measured in weeks and months is nowmeasured in hours and days. Minimal leadtimes, locally manufactured products,and standard shapes make this methodeconomically feasible. Deck formwork forcast-in-place concrete can be eliminatedwhen adjacent precast members areused. Combined with the reduceddisruption to traffic, shorter detour times,and minimal site impact afforded, thesocial benefits are significant.
Context-Sensitive DesignA context-sensitive design utilizes a
by Kevin R. Eisenbeis
SUSTAINABILITYSocial Benefits of Concrete BridgesHow Green is Our Valley?
The excellent fire and seismic resistance
characteristics of these structures further ensuresthe public well-being.
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The Route 100 precast box beam bridge
provides a shallow structure depth over
I-44 near St. Louis, Mo. Photo: MoDOT.
Aesthetic requirements played a key role in selecting the type of bridge for the 27th Street Bridge, Kansas City, Mo.
Photo: Harrington & Cortelyou Inc.
ASPIRE, Spring 2008|1
collaborative approach involving allkey stakeholders when considering thetotal setting in which a project will exist.Concrete structures adapt well to variousphysical settings often preserving scenic,aesthetic, historic, and environmentalresources. The advantage of concretebridges is apparent in the number ofcommunities improved by their use.
AestheticsConcrete bridges blend well with theirsurroundings. The simple, clean shapesprovide attractive spans in individual ormultiple arrangements. Low span-to-depth ratios create slender lines andenhance their graceful appearance.
Long Service LifeAnother key aspect of sustainabilityis longevity. When maintenance
requirements are minimized, the amountof effort and energy required to repairthe bridge in the future is minimized.
Recent advancements in the use ofhigher strength concretes combined withprestressing provide for extremely durableconcrete structures. Where corrosionof reinforcement is reduced, futuremaintenance requirements diminishaccordingly. Durable concrete bridges arelong-term structures, minimizing the costof future repairs and life-cycle energy
consumption.
Where Do We Go fromHere?We should first answer the question,why do we care? Regardless of personalfeel ings about g lobal warming,carbon credits, LEED certifications,or any of a myriad of green terms,it is important to realize our decisionshave consequences, and our actionscan make a difference. It seems safe to
say we all want to preserve or improveour environment, and we want ourchildren and our grandchildren to havea better environment than we enjoy. Aspractitioners in our industry we can takesteps that may make a difference.
With a few minor variations in currentmindset and practice, we can continueto improve on our bridge sustainability.Advocates for sustainability promotedesigning, building, and maintainingwith overall energy consumption in mind.For example, providing solar poweredlighting can reduce power requirements
while still meeting safety needs. Manytraffic signals and message signs utilizethis technology, why not bridge lighting?Lowering the power consumption forthe life of the bridge, including energyused in fabrication, distribution,installation, and maintenance, reducesits footprint in the realm of carbondioxide emissions. Designing with local
in mind can cut transportation costsand fossil fuel consumption in shippingmaterials and products. This aspect oftencomes into play now resulting in lowercosts for construction, but what abouton a macro level. Should we considerthe consequence in carbon emissionsfor shipping a product a long distance,from overseas for instance, just becauseit had the lowest initial cost? Remember,our decisions have consequences. Areasonable balance between economyand environmental concern is in order.
As summarized above, concrete bridgesprovide many social benefits. From fire-resistant and seismic-resistant structures,to rapid construction and attractive,long-term installations, concrete bridgesprovide sustainable solutions thatbenefit society. In our quest for continualimprovement, we should ask ourselves:Can we do more? Because our decisionshave consequences, we can decide tomake our childrens valley greener aswe continue to realize the benefit of
sustainable concrete bridges.
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Protecting Against
by Craig A. Shutt
Concrete can help bridges
resist a blazes high heat and
return quickly to service
On June 20, 2007, a fuel tanker truckrear-ended a loaded dump truck on StateRoute 386 under the Stop Thirty RoadBridge north of Nashville, Tennessee. Thetanker erupted into flames beneath the
233-ft-long structure, a two-span, two-cell, hollow box-beam bridge. Fearingdamage that would interrupt traffic for
many months, both on and below thebridge, inspectors, and maintenancecrews rushed to the site to conductstudies on the concrete once the firecooled. After analyzing the bridge and
finding no problems, traffic was restored
under the bridge to the busy stateroute as soon as pavement repairs werecompleted. Traffic returned to serviceon Stop Thirty Road after core sampleswere evaluated.
The analysis showed that the bridgeendured much heat but sustained verylittle damage, says Wayne Seger ofthe Office of Bridge Inspection andRepair at the Tennessee Departmentof Transportation. The affected spanwas 120-ft long. The bottom slabs ofthe hollow box-beams are 7.25-in.thick, and the sides of the boxsections along with the common wallbetween the cells are 1-ft thick withtwo mats of reinforcement. Class A,
3000 psi concrete and epoxy-coated
The analysis showed that the bridge enduredmuch heat but sustained very little damage.
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Following a fire on the Bill
Williams River Bridge in Arizona,
it was determined that the girders
could be repaired. Photo: Arizona
Department of Transportation.
Photo: U.S. Fish & Wildlife Service
reinforcement had been used toconstruct the bridge in 1981.
After the bridge cooled, potentialspalls were chipped off and concrete
cores were cut to allow engineers atCTLGroup in Skokie, Illinois, to performpetrographic analysis. The evaluationshowed that the concrete was in goodshape, so we removed the restrictedload posting signs and returned thebridge to service, he says.
Keeping CoolEngineers are well aware of the strengthand durability that concrete can offer forbridge designs, allowing longer spansand long-term life cycles with minimal
maintenance requirements. But the
material offers considerable resistance tofires that could otherwise render otherbridge types unusable.
The key problem is that bridge fires tend
to be exceptionally hot, as theyre causedby an external source of intense heat,such as fuel from an overturned truck ortankers carrying chemicals, says Richard B.Stoddard, Bridge Design Engineer with theWashington Department of Transportation,who inspected a fire-damaged bridge inhis region (for more on this project, see thefollowing article).
Tanker fires caused by highwayfuel-trucks or railway tanker cars areexplosive in nature and greatly exceed
the temperatures and rate of heating
prescribed in the ASTM fire-resistancetest, he said in his report. Additionally,the heat-transfer mechanism intanker fires is dominated by radiantenergy as opposed to hot-air andheat convection. Concrete, with itshigh specific heat, can better endurethese relatively short-duration, high-
temperature fires.
Concrete can
better endure theserelatively short-duration,
high-temperature fires.
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The heat from the Puyallup River Bridge
fire was intense enough to cause damage
to all 15 lines of girders.
Bridges Survive FiresA variety of bridges around the countryhave suffered spectacular bridge firesyet have been able to return to servicequickly due in part to the use of concrete.For instance, on July 28, 2006, a fueltruck crossing the Bill Williams RiverBridge on Route 95 in Parker, Arizona,crashed about halfway across thestructure. Built in 1967, the bridge spansthe Bill Williams Wildlife Refuge, whichreceives about 70,000 visitors per year.
The tanker spilled approximately 7600gallons of diesel fuel onto and underthe bridge, which then ignited andburned on the bridges AASHTO Type IIIprecast, prestressed concrete girders andcomposite reinforced concrete deck. Thefire-damaged girders did not show visiblesigns of loss of prestress but experienced
varying degrees of spalling. A reduced
girder section was rated for flexure andshear and compared to a prefire condition.It was determined that the fire resulted ina 6 percent reduction in the bridge loadrating for the short term and a 12 percentreduction for the long term. Based onthese results, and following a study ofmultiple alternatives, it was determinedthat the girders could be repaired. Bothlanes on the bridge have remained opento traffic since the accident.
The damage wasnt as bad as we initiallyfeared, says Martha Davis, Structural
Engineer for HDR Engineering Inc. in
Tucson, Arizona. The firm worked withCTLGroup to identify the depth of the firedamage in structural elements, determinethe extent to which spans were damaged,and note any reductions in sectionproperties and material strengths.
Their assessment found that theoverhang and shoulder in three spans,especially the ninth span, needed tobe replaced. The fuel spilled throughthe deck drains and expansion joints,spreading the fire under the bridge,
and the wind whipped the fire along
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A blazing car fire caused damage to
a bridge in Washington County, Ore.,but the affects were minimal and the
bridge was reopened to traffic after
an inspection.
The blackened beams of the Bell Isle
Bridge, Oklahoma City, Okla.,
were cleaned and the bridge
was reopened.
Photo: Oklahoma DOT.
Some spalling and exposed aggregate
were noted during the inspection of the
Washington County, Ore., fire, but it was
not sufficient to require repairs.
Although flame temperatures at this methanol-fueled
tanker fire under the Puyallup River Bridge, Wash.,
reached 3000 F, the precast concrete bridge was
reopened to traffic the next day.
the bridges barrier and overhang,Davis explains. But the girders in thosespans, and in all of the others, retainedtheir structural integrity. Transportationofficials closed the shoulder on theaffected span to keep vehicles off theoverhang and to protect the barrier until
repairs could be completed.
Those repairs are still to be scheduled, shenotes. The plan is to save as much of the
existing reinforcement as possible and
rebuild the overhang, repair damage to the
girders where reinforcement was exposed
and concrete spalled, and add a protectivecoating to the deck to inhibit corrosion. The
bridge also is being monitored to ensure no
signs of additional damage arise.
An even faster return to service took
place for a ramp to the NorthwestExpressway in Ok lahoma C i ty ,Oklahoma, when a truck crashed on thenearby Belle Isle Bridge on January 28,2006. A portion of the truck becameairborne and crashed to the groundnear the ramp, where the resulting fireblackened the ramps AASHTO Type IIprestressed concrete beams. But afterevaluation, the blackened beams werecleaned and the bridge was reopened.
There was superficial damage thatwe repaired, explains Walter Peters,Assistant Bridge Engineer for Operationsin the Bridge Division of the OklahomaDepartment of Transportation. It wasmostly smoke damage and minor spalls.
A similar result occurred at a precastconcrete bridge in Washington County,Oregon, in November 2004. A derelictcar was abandoned in an area beneaththe bridge and set on fire, causingcharred concrete on the bridge above anddisruption to traffic. The damage occurredat about midspan on a 37.5-ft-long span
using 18-in.-deep voided slabs. The fire
was hot enough to melt aluminum andleave it puddled on the ground nearby,reports Greg Clemmons, OperationsEngineer for the Washington County LandUse and Transportation Department.
An inspection of the bridge showed that
spalling occurred in an approximate areaof 2 sq ft and was 1/2- to 3/4-in. deep.In several areas, the concrete also turnedpink, indicating it had been exposedto heat of at least 500 F. Followingpressure washing to remove soot, adetailed inspection took place, includinghammer tests at various locations.
Following the inspection, the bridge wasreopened to traffic. The prestressingsteel did return to its full strengthwithout causing any deformation inthe bridge girders following the fire,Clemmons reports. Debonding of thestrand possibly took place at the centerof the component, he notes, but centraldebonding would not produce anysignificant concern if the ends remainintact. There was localized damage, butit did not impact the bridges operation.
Although the department consideredcleaning and repairing the spalledareas immediately, the damage wasdetermined to be so minor that thebridge instead was put onto the countys
accelerated inspection list.
Fast Replacement is OptionAnother approach to maintaining trafficon a precast concrete bridge was usedby the Connecticut Department ofTransportation. A tanker truck carrying8000 gallons of gasoline jack-knifedduring an accident, spilling its contentsover and under the 80-ft-long bridgeover the Norwalk River near Ridgefield,Connecticut. The resulting fire exposedthe precast concrete bridge to severe
heat and fire damage.
The prestressing steel did return to itsfull strength without causing any deformationin the bridge girders following the fire.
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After a tanker truck overturned, caught fire, and
burned out on a bridge spanning the Norwalk
River near Ridgefield, Conn., engineers decided
to resupport the 50-year-old precast concrete
bridge with intermediate supports. The bridge
reopened to traffic in four days.
Gasoline that spilled from the tanker-truck accident on the bridge over the
Norwalk River caused spalling on the
precast concrete but left it in reasonably
good shape, engineers reported.
For more information on this or other
projects, visit www.aspirebridge.org.
The 50-year-old bridge, one of thefirst precast concrete bridges built inthe United States, suffered significantamounts of spalled concrete on itsbeams, reports Arthur Gruhn, ChiefEngineer. Reinforcement was exposed
in a number of locations. We really hadno idea how strong the bridge still was,he says. Despite its age, the bridge hadbeen in good condition, and there hadbeen no plans to replace it.
The design team moved into actionquickly, setting up a detour andproviding an initial inspection on theday of the accident. On day two,a contractor and remediation crewexamined the bridge to determine itsstatus. The team decided that the bridgewas still structurally sound but neededsome temporary intermediate supportto ensure its stability.
Two heavy steel support beams wereadded, one under either edge forthe length of the span, and threeadditional, shorter beams were insertedperpendicular to these at the one-quarter and one-half points. In addition,a Jersey barrier was placed along thedamaged bridge railings.
We really couldnt gauge how much
damage the fire had done, but we could
see the bridge still was in reasonablygood shape, he says. We wereconfident that if we shortened the spansof the precast concrete beams, enoughstrength remained to support the loads
until a replacement could be built.
Installing the support beams took twomore days, and the bridge reopenedto traffic only four days after the fireoccurred. A temporary bridge wascreated adjacent to the bridge, and onceit opened, work on replacing the originalbridge with another precast concreteversion began. That work was completeda few months later, producing a brandnew bridge to replace the fire damagedone in only four months.
In fact, a later evaluation of the beamsperformed at the FHWA Turner-FairbankHighway Research Center showed thatconcerns over the short-term structuralintegrity of the beams were groundless.The investigation found that the flexuralcapacity of the beams had not beendegraded significantly as compared totheir anticipated capacity, wrote GaryL. Henderson, Director of the Office ofInfrastructure at the Federal HighwayAdministration in his report dated
February 2007. However, their long-term durability may have been degradedby the fire, he noted, so replacementwould have been needed eventually. SeeConcrete Connectionson page 52 for thewebsite address with the full report.
Avoiding such replacements canensure budget and time are spent onprojects where they are needed. HDRsDavis knows the balance that must beobtained. If there was a close detourfor the Bill Williams River Bridge, andmoney was no object, we might do
more to improve the bridge, just to be
on the safe side, she says. But theclosest detour is 100 miles away.
Even to do the work that will be neededon the overhang will require closing onelane and operating alternating-directionaccess during construction. Work likethis totally impacts traffic, especiallyin an environmentally sensitive area,she says. But that disruption is nothingcompared to what would be requiredhad the bridge been unusable and usershad to drive 100 miles out of their way
until a new bridge was completed.
Two major fires on highway structuresin California last year demonstrated thedisruption that they produce. The firstin April was caused by a gasoline tankertruck that crashed and exploded intoflames at the MacArthur Mazeoneof Californias heavily traveled freewayinterchanges in the San Francisco Bayarea. Although the steel superstructureof one connector collapsed, only 4 ftof concrete at the top of two columns
supporting one outrigger bent werereplaced. The original steel bent cap wasreplaced with a concrete one because itcould be manufactured more quickly.
The second event in California occurredin October when a truck exiting a550-ft-long truck-bypass tunnel on I-5near Santa Clarita lost control resultingin a multi-vehicular collision and massivefire in the tunnel. Although the collisionoccurred at the exit from the tunnel, thewinds drove the flames so that most firedamage occurred at the tunnel entrance.The tunnel structure consisted of concretebox girders supported on top of concretestrutted abutments. Repairs consisted ofbuilding a new wall in front of portions ofthe wall that were damaged and replacingapproximately one-sixth of the totalsuperstructure with precast girders and acast-in-place concrete deck. This solutionwas adopted as the most conservativeapproach and allowed the tunnel to open15 days ahead of the deadline.
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In December 2002, a railroad tankercol l i s ion caused a f i re under a
prestressed concrete girder bridge
crossing the Puyallup River in Tacoma,
Washington. The bridge, constructed in
1997, had span lengths of 146 ft with
W74 girders spaced at 5-ft 0-in. centers.
Specified 28-day concrete strengths
were 7000 psi in the girders and 5000
psi in the columns and bridge deck.
The fire consumed 30,000 gallonsof methanol, engulfed Span 8, and
maintained a high flame temperature
for approximately 1 hour. The bridge
was closed immediately pending further
inspections. The bridge displayed no
unusual deflections or misalignments
and was reopened to commuter traffic
and legal weight trucks on the morning
after the fire.
Visual Inspectionand MappingVisual inspection of both columns atPier 9 approximately 60 ft from thesource of the fire, showed 2-in.-deepspalls that exposed spiral reinforcementfor the full height of the column. Theconcrete inside the spiral soundedlike delaminated concrete. Furtherinvestigation revealed delaminations
A CASE STUDY
by Richard B. Stoddard, Washington State Department of Transportation
Evaluating
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within the concrete just inside thespiral cage and vertical reinforcement.The crossbeam above the columnshad several areas of spalling but noreinforcement was exposed.
All 15 lines of girders in Span 8 weredamaged and the corners of thebottom flanges could easily be removedto expose the outermost strands. Thesoffit of the concrete deck displayed noevidence of spalling.
Visual inspection of the damage in Span8 included recording the concrete colorvariations on the soffit of the bottomflanges that corresponded to changesin concrete condition. The color regionswere described as extreme-white,ash-white, white-gray, and soot. The
different colors corresponded withdifferent exposures to the fire with theextreme-white region representing themost intense exposure directly over thefire source.
Concrete HardnessMappingIn accordance with the recommendationsfor Post Fire Examination of the PCI Design
for Fire Resistance of Precast, PrestressedConcrete, hardness testing was performedon the bottom flanges and webs of thegirders using a Schmidt hammer. Thepurpose of the tests was to map relativechanges in concrete hardness alongthe length of each girder. The reboundhammer readings for the soffit of thebottom flanges in Span 8 ranged from 42to 61 compared to 61 in girder concretenot affected by the fire. The minimumhardness occurred directly over the heatsource and in general, hardness increasedwith distance away from the heat source.
The web hardness readings did notfollow a pattern of regular changebecause shadowing by the bottom flangeaffected the distribution of web damage.The bottom flange protected some partsof the webs from severe fire damage.
Prestressing StrandThe prestressing steel in the girdersconsisted of 1/2-in.-diameter 270 ksistrands. Concrete surrounding thestraight strands in the bottom flangewas easy to remove with a l ightrock hammer. Because of the hightemperatures, there was concern that
the strands could have lost strength andthat relaxation of the prestress forcecould have occurred.
Prior to removing samples of prestressingstrands for material testing, simpledeflection tests were performed tocalculate the prestressing force. The testswere conducted before the strands werecut and after the strand replacementsplices were tensioned. The stranddeflections were induced by hanging a173 lb weight on the strand. Deflectionswere measured multiple times by twoinspectors using a dial caliper with ameasurement accuracy of 0.001 in.This method was estimated to have aprobable accuracy of 5 percent and wascertainly accurate to within 10 percentof the actual tensile force. Based on
this approach, the strands in the hottestzones appeared to have retained 100percent of their design force.
Three samples of strand were removed andtested for yield strength, tensile strength,and modulus of elasticity. The strandsamples met the requirements for 1/2-in.-diameter uncoated seven-wire prestressingstrands per ASTM A 416-96 indicating thatno metallurigical changes occured.
The fire engulfed Span 8 and maintained a high
flame temperature for approximately 1 hour.
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All 15 lines of girders in Span 8
were damaged by the fire but
the bridge was opened on the
next morning.
Spalling of concrete cover on the columns
resulted in areas of exposed spiral
reinforcement.
The pink color shown in this girder from the Puyallup bridge fire indicates that the
concrete was exposed to temperatures higher than 500 F.
Concrete Core SamplesEight vertical concrete cores from thehot zone, two vertical cores from thecoolest zone, and eight horizontal coresfrom the hot zone were removed fromthe prestressed concrete beams. Sevencores were examined petrographicallyin general accordance with ASTMC 856. The extent and severity of firedamage was based on observed changesin aggregate and cement paste color,mineralogy, and microstructure. Based onthe petrographers evaluation, which alsoincluded some informal heating tests,the state was convinced that surfacetemperatures on the bottom flangesoffits exceeded 1500 F during the fire.
Compression tests performed on coresamples indicated that much of theundamaged concrete had a compressivestrength exceeding 9000 psi. Significantportions of core samples from the
hottest zone, however, were fracturedand untestable.
Eight concrete cores were taken fromthe two columns at Pier 9. Theseconfirmed the existence of delaminationsin the interior core of the column. Themaximum depth of fracture was foundto be 5 in. from the original surfaceand more than 1 in. inside the verticalcolumn reinforcement. Aside from thedelaminations, the concrete remaining
in the column appeared to have verygood strength.
A core sample from the crossbeam atPier 9 did not show any abnormalities
and indicated that the crossbeamsustained only superficial damage fromthe fire.
SummaryThe railroad tanker fire subjected all 15girders in Span 8 to intense heat in ashort period of time. Flame temperatureswere estimated to be approximately3000 F and surface temperatures on thesoffit of the prestressed concrete girdersmay have reached 1700 F. Internaltemperatures in the bottom flange and
webs were estimated to range from500 to 1100 F. The prestressing steelsurvived the fire without noticeable lossof prestress.
Rapid identification of concrete damagezones can be made by observing thevariation in concrete color immediatelyfollowing a fire. The visual colormapping correlated very well withvariations in concrete hardness. Therebound hammer test validated thevisual observations and provided an
objective description of the damagedareas. With this information, rationaldiscussions could be made about repairor replacement.
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Some surface damage occurred in the top
flanges.
Damage concrete surrounding the straight
prestressing strands was easy to remove.
ReferenceDesign for Fire Resistance of Precast,Prestressed Concrete, Second Edition,MNL-124-89, Precast/PrestressedConcrete Institute, Chicago, IL, 1989,96 pp.
AcknowledgementThis article is based on a full-length papertitled Inspections and Repair of a FireDamaged Prestressed Girder Bridge,presented at the International BridgeConference, Pittsburgh, June 2004, PaperNo. IBC-04-17 which is available at www.aspirebridge.org/resources._____________________
Richard B. Stoddard is Bridge DesignEngineer with the Bridges and StructuresOffice of the Washington StateDepartment of Transportation.
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