Editorial by John D. Armeni,ASBI President 2009-2010

S E G M E N T SA M E R I C A NS E G M E N T A L B R I D G EI N S T I T U T E

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I N S I D E

COMMUNICATION NEWSFirst ASBI International Symposium.......2, 3

New ASBI Organizational Members ...........4

2009 ASBI Membership Directory ..............4

2009 Grouting Certification Training .........4

2009 Convention ........................................4

PCI Appoints Nickas to Transportation Post .....................................5

Susan Lane Appointed PCA Program Manager, Transportation Structures ............5

Credit Corrections – Fall 2008 Newsletter .................................. 5

Gerard F. Fox, 1923-2008 ...........................5

PROJECT NEWSKanawha River Bridge, West Virginia ......6, 7

Fourth Street Bridge, Pueblo, Colorado ........................................8

Hurricane Ike Impacts 7 Texas Bridges, Texas ........................................................9, 10

The New I-35W Bridge, Minneapolis, Minnesota......................10, 11

I-76 Allegheny River Bridge, Oakmont, Pennsylvannia ............................12

US 191 Bridge over the Colorado River, Moab, Utah ...............................................12

RESEARCH NEWSRecommendations for “Shear Design Provisions for Segmental Box Girder Bridges of the AASHTO – LRFD Bridge Design Specifications, 4th Edition, 2008 Interim” by Alejandro R. Avendano and Oguzhan Bayrak, University of Texas at Austin ................................................. 13-16

LOOKING TO THE FUTURE

Editorial

We are very pleased to welcome W. R. “Randy” Cox as ASBI’s new Manager in 2009 following a 27 year career with the Texas Department of Transportation. For the past four years, Randy served as TX DOT’s Bridge Division Director.

While it is clear that 2009 will be a challenging year economically, we are confident that the use of segmental construction will continue to grow in 2009 and beyond. The cost competitiveness of segmental construction in comparison to steel is reflected in a redesign now underway for the Pennsylvania Turnpike. Commission Project on the Mon/Fayette Expressway, Section 51H. This project was designed with a steel plate girder superstructure featuring a 518 foot navigational main span over the Monongahela River. The project is being redesigned by FIGG as a Contractor Alternate Cast-in-Place Segmental Bridge for Walsh Construction Company as the low bidder on July 23, 2008.

The unstable price of gasoline in 2008 and the current state of the economy has dramatically increased interest in light rail for commuters. The Seattle Sound Transit Light Rail Project completed in 2008 is the latest U.S. demonstration of the significant advantages of segmental technology for light rail projects. On this project, segmental construction reduced construction time, lowered cost about

15 percent, minimized interference with traffic by using an overhead gantry to erect segments, provided an aesthetically pleasing appearance, and was designed to meet high seismic needs. Major light rail projects using segmental construction are now being developed in Honolulu, Miami, and Washington, D.C.

Segmental construction has been widely used in recent design-build projects in the U.S. and Canada. Design-build project delivery was used very successfully for the Victory Bridge in New Jersey, the Otay River Bridge near San Diego, the Penobscot Narrow Bridge and Observatory in Maine, and the I-35W Bridge Replacement Project in Minneapolis. These projects are all illustrative of the potential of segmental construction for accelerated bridge construction.

In closing, it is our purpose as ASBI Members to continue to communicate the substantial benefits and advantages of segmental construction (as discussed above). Building on the achievements

of recent years, there is a great opportunity to keep the momentum going in the future.

Volume 53 Winter 2009

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PHOTO GALLERY KEY1. Convention General Session in the Fairmont Hotel Grand Ballroom. 2. Rick Land, Chief Engineer, Caltrans giving Caltrans Keynote presentation during the Monday General Session. 3. Michelle Virlogeux, Consultant, France, presenting Symposium Keynote address on “Structure and Architecture of Bridges”. 4. Linda Figg, FIGG, General Session presentation on I-35W St. Anthony Falls Bridge: A Modern Segmental Bridge for the Future, MN. 5. Symposium luncheon in the Gold Ballroom of the Fairmont Hotel. 6. Raymond J. McCabe, ASBI President 2007-2008, HNTB Corporation, presiding at the Monday luncheon. 7. Man-Chung Tang, T.Y. Lin International, Monday Keynote presentation on “Partially Cable Supported Bridges”. 8. Myint Lwin, Federal Highway Administration, U.S. Department of Transportation, giving Tuesday Keynote luncheon presentation on “FHWA Perspective on Segmental Concrete Bridges”. 9. 2008 ASBI Leadership Award Recipients: Raymond McCabe, HNTB Corporation, Ralph Salamie, Kiewit Pacific

C O M M U N I C A T I O N N E W S

The first ASBI International Symposium held November 17-19, 2008 at the Fairmont Hotel in San Francisco was attended by 388 Engineers and Construction Personnel, as well as 64 accompanying persons. The total attendance of 452 surpassed the previous record attendance of 415 at the 2007 Las Vegas Convention. Following are representative “scenes from the Symposium”:2

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Company; Elie Homsi, FLATIRON; Lind Figg, FIGG; John Crigler, VSL. 10. Cliff Freyermuth, ASBI, at Wednesday Keynote luncheon presentation “ASBI – A 20 Year Retrospective, and a Look at the Future”. 11. John Armeni, Armeni Consulting Services, LLC, ASBI President-Elect 2009-2010 presenting the 2008 Leadership Awards. 12. Cliff and Alice Freyermuth following Wednesday luncheon gift presentation recognizing 20 years of service to ASBI. 13. Luncheon recognition of Dawn White, ASBI Director of Marketing, for five years of outstanding service. 14. International Bridge Technologies Exhibit Booth. 15. Schwager Davis, Inc. (SDI) booth; Guido Schwager, SDI; Dave Swanson, Consultant; Peter Matt, Consultant, Switzerland. 16. An International Quartet of Symposium Speakers on the boat tour of the San-Francisco-Oakland East Bay Skyway. Akio Kasuga, Sumitomo Mitsui Construction, Japan; Jacques Combault, FINLEY Engineering Group, France; Cliff Freyermuth, ASBI; and Peter Matt, Consultant, Switzerland.

Photos: ©2009 David Braun Photography

FIRST ASBI INTERNATIONAL SYMPOSIUM ON “Future Technology for Concrete Segmental Bridges”

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A m e r i c A n S e g m e n t A l B r i d g e i n S t i t u t e

2009MeMbership Directory

April 20 – 21, 2009

J.J. pickle research Campus . The Commons Center

10100 Burnet Road, Building 137 . Austin, Texas

2009 GroutinG

CertifiCAtion

training1

Co-SponSored by

the texaS department of tranSportation

TRA IN ING PRoGRAm

Monday, April 20

7:30 — 8:30 a.m. registration

8:30 — 9:00 a.m. introduction & Welcome, (Speaker to be determined)

9:00 — 9:45 a.m. Grout Materials, Andrea Schokker,

University of Minnesota, Duluth

9:45 — 10:30 a.m. Project Specifications, Andrea Schokker,

University of Minnesota, Duluth

10:30 — 10:45 a.m. Break

10:45 — 11:20 a.m. Equipment, Gregory Hunsicker, VSL

11:20 — 12:00 Noon Review PTI Specifications, Andrea Schokker,

University of Minnesota, Duluth

12:00 — 1:00 p.m. lunch

1:00 — 2:00 p.m. Grouting On Site Video, Brett Pielstick,

Eisman & Russo

2:00 — 3:00 p.m. Small Test Demonstrations, Andrea Schokker,

University of Minnesota, Duluth

3:00 — 3:15 p.m. Break

3:15 — 4:45 p.m. Large Specimen Demonstrations, Andrea Schokker,

University of Minnesota, Duluth

4:45 — 5:15 p.m. Adjourn

tuesday, April 21

8:00 — 8:45 a.m. Detailing, Teddy Theryo, Parsons Brinckerhoff

8:45 — 9:30 a.m. Special Cases and Problems, Gregory Hunsicker, VSL

9:30 — 10:00 a.m. I nspection & Testing, Brett Pielstick, Eisman & Russo

10:00 — 10:30 a.m. Owners’ Perspective, Brian D. Merrill, Texas Department

of Transportation

10:30 — 10:45 a.m. Break

10:45 — 11:50 a.m. exam

11:50 — 12:00 Noon exam review

12:00 Noon Adjourn

Demonstration Grouting Equipment provided by Dywidag Systems Int’l, USA, Inc.

Prepackaged Grout provided by BASF Construction Chemicals – Building Systems.

PRoGRAm INfoRmAT IoN

ASBi Grouting Certification program purpose

The purpose of the ASBI Grouting Certification Training

is to provide supervisors and inspectors of grouting

operations with the training necessary to understand

and successfully implement grouting specifications for

post-tensioned structures.

ASBi Certified Grouting technician

Individuals who successfully complete the ASBI Grouting

Certification Training and provide verifiable documentation

of three years of experience in construction of grouted

posttensioned structures, will receive a certificate as an

“ASBI Certified Grouting Technician.” The certificate will be

valid for a period of five years, and will be renewable at

the end of that time through participation in an on-line

recertification examination. To receive this certificate,

submission of verifiable documentation of experience

is required at the time of registration for the training.

ASBi Grouting training Certificate

Individuals who successfully complete the ASBI Grouting

Certification Training and do not have three years of

verifiable documented experience in construction of

grouted posttensioned structures, will receive an “ASBI

Grouting Training Certificate.” In the five year period

following completion of the training, individuals with

this certificate may obtain an “ASBI Certified Grouting

Technician Certificate” upon submission of verifiable

documentation of three years experience in construction

of grouted post-tensioned structures.

reexamination

Individuals who do not pass the examination during an

ASBI Grouting Certification Training class will be eligible

to participate in the examinations given at subsequent

training classes without an additional registration fee,

with or without participation in the training class.

florida Department of transportation Accreditation

The Florida Department of Transportation has accredited

the ASBI Grouting Certification Training Course; therefore,

individuals who pass the final examination of the ASBI

course satisfy one of the requirements for becoming a

Qualified Grouting Technician with the Florida Department

of Transportation. To find out how to apply for qualifica-

tion contact: Construction Training Qualification Program

(CTQP), P. O. Box 116586, Gainsville, Florida 32611

Telephone: (352) 846-3593 email: ctqp@ce.ufl.edu

professional engineering Development Hours

For Professional Engineers, we will provide certificates

for 12 professional development hours on request for

use in meeting Professional Engineering Registration

requirements.

2009 ASBI Membership Directory

A copy of the 2009 Membership Directory is enclosed with this edition of the Newsletter. We are very pleased that this edition of the directory is enhanced and supported financially by 22 advertisers.

Please advise the NEW ASBI office in Buda, Texas of any necessary correc-tions to the address listings in the Newsletter.

The new office address is:

American Segmental Bridge Institute142 Cimarron Park Loop, Suite F, Buda, TX 78610 (512) 523-8214, FAX: (512) 523-8213

BENTLEY SYSTEMS INC.685 Stockton DriveExton, PA 193411-800-BENTLEYe-mail: Gabe.Norona@bentley.comwww.bentley.comGabe Norona

GPRM Prestress91-063 Malakole StreetKapolei, HI 96707(808) 682-6000FAX: (808) 682-6001e-mail: aboyd@gprmp.com Andy Boyd, Sales Manager

LARSA, Inc.105 Maxess Road, 115NMelville, NY 11747(212) 736-4326FAX: 631-249-3089email: ali@larsa4d.comwww.larsa4d.comAli Karakaplan, President

LEADER GRAPHIC DESIGN, INC.5410 Newport Drive, Suite 44Rolling Meadows, IL 60008(847) 564-5409FAX: (847) 564-3882www.LeaderGraphics.commleader@leadergraphics.comMark Leader, President

2009 Convention

Mark your calendars! The 2009 ASBI Convention is scheduled for October 26-27 at the Hilton Minneapolis. The Tuesday afternoon bridge tour is scheduled to include six Crosstown Expressway Bridges which utilize AASHTO-PCI-ASBI Standard Segments, and the I-35W Bridge Replacement Project.

2009 Grouting Certification Training

Information is enclosed on the 2009 ASBI Grouting Certification Training event scheduled April 20-21, 2009 at the J.J. Pickle Research Campus at the University of Texas at Austin. Please check the ASBI website www.asbi-assoc.org for on-line registration.

PERI Formwork Systems, Inc.7135 Dorsey Run RoadElkridge, MD 21075(410) 712-7225FAX: (410) 796-8683e-mail: Tom.Ameel@peri-usa.comwww.peri-usa.comTom Ameel, CEO

These five new 2008 Organizational Members, in addition to the eight new members listed in the Fall 2008 edition of the newsletter, represent an increase of 28 percent in ASBI Organizational Membership. We are very appreciative of this additional support of ASBI efforts to advance segmental design and construction technology.

New ASBI Organizational Members

We are very pleased to welcome five new ASBI Organizational Members: Bentley Systems, Inc., GPRM Prestress, Larsa, Inc., Leader Graphic Design, and PERI Formwork Systems.

The addresses and contact persons are as follows:

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PCI Appoints Nickas to Transportation Post

The Precast/Prestressed Concrete Institute (PCI) has appointed William N. Nickas, P.E., as Managing Director of Transportation Services, effective September 29, 2008. In this position, Nickas will support the precast concrete structures industry in developing and delivering current and future high-quality, durable, and sustainable systems for building bridges, pavements, and other transportation-related structures. This position had previously been held by John Dick, who retired earlier that year.

Nickas’ entire 25-year career has been spent in the design and construction of transportation facilities in both the public and private sectors. He joined the Florida Department of Transportation (FDOT) after graduating from the Citadel in 1983. In 1987, he joined the private sector, where he has served as a design engineer, project manager, and principal. In his second tenure at FDOT, Nickas served as state structure design engineer. In this role, he was responsible for all structure-design policy development for the state, as well as major and complex bridge project issues. In January of 2007, he joined Corven Engineering as a principal engineer.

Gerard F. Fox, 1923-2008

Gerard F. Fox of Garden City and East Hampton NY died Dec 12, 2008. Born 1923 in Manhattan, he graduated from LaSalle Academy and served three years in the Army Air Corps in WWII at Eglin Air Base in Florida where he worked on a research project to develop bomb sights. Graduated from Cornell University (civil engineering) with distinction (1948), elected to Tau Beta Pi and Chi Epsilon, member of Sigma Phi Epsilon.

A licensed Professional Engineer, he was a bridge designer at HNTB Corp for 40 years retiring in 1988 having been a Partner for 21 years, responsible for bridge projects firm wide. Prior to becoming a partner, he was chief structural engineer in the New York City Office of HNTB directing structural design, detailing and the preparation of plans and specifications for bridges and related structures.

He was in charge of the design of the longest segmental concrete cable-stayed bridge in North America - the Dames Point Bridge in Jacksonville, Florida, originally designed in both concrete and steel, with a center span of 1,300 feet and the Rio-Niteroi Bridge in Brazil, which included precast concrete segmental viaduct sections which have a total length of 27,034 ft. and a record steel box girder span of 984 feet. The Dame Point Bridge and the Rio-Niteroi Bridge awarded the American Consulting Engineers Council (ACEC) Grand Conceptor Award.

He was elected to membership in the National Academy of Engineering in 1976 for contributions in structural theory with innovative elements of construction practice in building bridges.

Credit Corrections – Fall 2008 Newsletter

Form Travelers for the Allegheny River Bridge were leased to Walsh Construction by Schwager Davis, Inc. NRS-Asia was involved in the design and fabrication.

Prepackaged Grout for the I-35W Bridge Replacement was supplied by Sika.

Small movement strip seal expansion joints for the I-35W Bridge Replacement Project were supplied by Watson Bowman Acme – A BASF Company.

The I-35W Bridge Replacement Project credit listing for post-tensioning materials was given as DSI rather than Dywidag Systems International, USA, Inc. (DSI).

Susan Lane Appointed PCA Program Manager, Transportation Structures

Susan Lane has joined PCA as Program Manager, Transportation Structures (including bridges). Most recently Sue was Manager, Codes & Standards for the American Society of Civil Engineers. Previously, she worked for 12 years for the Federal Highway Administration and earlier designed bridges at Parsons Brinckerhoff, a consulting engineering firm. Sue has B.S. and M. S. degrees in Civil Engineering from Pennsylvania State University and is a Licensed Professional Engineer.

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Figures 2 and 3 - (Photo right and far right respectively) Work continues on the Kanawha River Bridge with completion expected by the end of 2010.

Owner: West Virginia Department of Transportation (WVDOT)

Designer: T.Y. Lin InternationalEngineer of Record: T.Y. Lin

InternationalContractor: Brayman Construction

CorporationConstruction Engineer: FINLEY

Engineering Group, Inc.Construction Engineering Inspection:

WVDOT – Division of HighwaysFormwork for Precast Segments:

DOKA, USA, Ltd.Form Travelers for Cast-in-Place

Segments: STRUKTURASPost-Tensioning Materials/Stay Cables:

VSLPost-Tensioning Bars: Dyson

Corporation

Kanawha River Bridge Construction, WV

Work on the new I-64 Kanawha River Bridge (Figs. 1, 2 and 3) in South Charleston, West Virginia continues to go well. VSL is working closely with the General Contractor, Brayman Construction Company, to supply the post-tensioning systems for the cast-in-place concrete bridge. In addition to furnishing over 130,000 lbs. of post-tensioning bars manufactured by Dyson, VSL is also providing approximately 1,085 tons of 0.6" diameter post-tensioning steel. To meet the enhanced durability requirements of the project, VSL's PT-PLUS™ plastic duct system is being used. Along the 1-3/8" P-T bar being used, the tendons sizes are 6-31, 6-22, 6-19, 6-12 & 6-4.

P R O J E C T N E W S

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Figure 1 - The Kanawha River Bridge shown in this rendering has the record span in the U.S. for a concrete box girder at 760 ft. (Photos and illustration courtesy of T.Y. Lin International..)

8 1Figure 4 - Cast-in-place box-girder Span 1WB has been completed and will provide the starting point for cantilever construction of the segmental span across the Arkansas River. The background shows the active rail tracks that will be crossed by the 378' span. (Image courtesy of FIGG).

Owner: Colorado Department of TransportationDesigner: FIGGContractor: Flatiron Intermountain ConstructorsConstruction Engineer: FINLEY Engineering Group, Inc.Construction Engineering Inspection: FIGGForm Travelers for Cast-in-Place segments: VSLPost-Tensioning Materials: VSLBearings and Expansion Joints: Joints – Watson Bowman Acme – A BASF

Company; Bearings – The D.S. Brown CompanyPrepackaged Grout: Grout – SikaPier Forms: DOKA and EFCO

Fourth Street Bridge, Pueblo, Colorado

Construction of the new 4th Street Bridge in Pueblo, Colorado for the Colorado Department of Transportation began on October 17, 2007. The bridge will span the Arkansas River, a flood protection wall that is celebrated as the world’s longest mural, and 28 sets of heavy rail tracks in the Pueblo Rail Yard. Flatiron Intermountain Constructors is building the concrete segmental structure that will contain Colorado’s longest highway span at 378'. The community selected theme of Natural Environment/Pueblo Heritage is evident in the pier aesthetics and other project features. Concrete segmental construction was the best solution for building over the active railroads with economy and quality (Fig. 4).

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Figure 6 - Cables securing bottom slab of segmental box girder to approach bent.

Figure 5 - Matagorda Balanced Cantilever one month prior to landfall of Hurricane Ike.

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Hurricane Ike Impacts 7 Texas Bridges by Dan Van Landuyt, Texas DOT

On September 13, 2008, Hurricane Ike, a strong category 2 storm, made landfall in southeast Texas. Five Balanced Cantilever and two Cable-Stayed bridges were in its path. Two of the bridges, Trinity (450' main span) and Matagorda (320') (Fig. 5), were in full cantilever, but lacked the last few approach span segments that would have secured them to the approach bents. In the days just prior to landfall, contractors for both bridges lashed the back span to the approach bent via diagonal cabling (Fig. 6).

In spite of the fact that the bridges were in their most vulnerable construction state and one of them (Trinity) experienced a near-direct hit, neither of the two bridges

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Figure 8 - The completed I-35W bridge structure incorporates the pier shape, white color, abutment walls faced with native stone, and other aesthetic features selected by the community. (Photo courtesy of FIGG).

Figure 7 - Segmental Bridges in the path of Hurricane Ike.

The New I-35W Bridge, Minneapolis, Minnesota

The I-35W Bridge (Figs. 8 and 9) is a concrete segmental bridge that was designed and built in 11 months, saving 3 months on the already aggressive 15 month schedule. The bridge opened to traffic on September 18, 2008, achieving the Minnesota Department of Transportation’s vision for quality, safety, and innovation. Segmental technology took center stage as the 120 segments for the 504' main span across the Mississippi River were placed in just 47 days. Close coordination of the design/build team, combined with goal-oriented construction methods, allowed for successful completion of the I-35W Bridge within the accelerated schedule and with no lost time due to accidents.

Concrete segmental bridge design and construction created the optimum solution to achieving this redundant, sustainable Interstate bridge. Eco-friendly materials, concrete in the gateway sculptures that cleans the air, and the first use of LEDs for major highway lighting will provide long term benefits for the environment and an example of sustainable design for other major bridges. Smart Bridge technology, incorporating 323 sensors installed throughout the bridge, will provide real-time data to assist the Minnesota Department of Transportation in managing operations and provide valuable feedback about bridge traffic patterns, infrastructure maintenance and security, and design sustainability. Community involvement throughout the project helped to shape the aesthetics of the

demonstrated any sign of damage. The most significant problems were work stoppage, flooded job trailers, and submerged construction materials.

Similarly, the completed bridges survived the storm without any ill effects. This includes the 1250' Fred Hartmann Bridge with superstructure height of nearly 200 feet that was directly in the path of the hurricane.

Figure 7 shows the locations of segmental bridges near the storm, their orientation, construction type and main span length. The Maximum Sustained 1-Minute Wind Speeds are also provided. These speeds were obtained from the Atlantic Oceanographic and Meteorological Laboratory NOAA Hurricane Research Division utilizing their unique HRD Surface Wind Analysis System. This system relies on data gathered from various locations (ships, buoys, land-based stations and reconnaissance aircraft) which are processed to create a contour map of wind speeds at a level

of 33 feet. The exposure condition is open terrain with adjustment made only for marine or land location. Inland wind speeds have not been fully synthesized as of this writing and are estimates only. Given that the shortest

of these bridges (Trinity) has a vertical clearance of 50' and a maximum structure depth of 25', it is likely that the wind speeds at the level of the superstructures were even greater than those indentified here.

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Figure 9 - On September 18, 2008 at 5:00 a.m., the I-35W Bridge opened to traffic only 11 months from notice to proceed with construction. (Photo courtesy of FIGG).

Figure 10 - The 30’ tall precast concrete gateway sculptures were inspired by the universal symbol for water and are made of cement that cleans the air. (Photo courtesy of FIGG).

Owner: Minnesota Department of TransportationDesigner: FIGGContractor: FLATIRON/MansonConstruction Engineer: FIGGConstruction Engineering Inspection: FIGGFormwork for Precast Segments: EFCOPost-Tensioning Materials: Dywidag Systems International, USA, Inc. (DSI).Bearings and Expansion Joints: Bearings – RJ Watson; Joints: The D.S. Brown

Company, large movement modular joints; Watson Bowman Acme – A BASF Company, small movement strip seals

Prepackaged Grout: SikaEpoxy: Pilgrim

elegant design during an interactive design charette, provided educational opportunities for local students, and kept the public informed about construction progress (Fig. 10).

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Figures 12 - Rendering of the new US 191 bridge over the Colorado River near Moab, Utah shows how the bridge will blend with the landscape and preserve its natural beauty. The bridge was developed to appear as if it is “born of the earth”. (Image courtesy of FIGG).

Figure 11 - October 9, 2008 — Walsh Construction lowers the soffit of the upstation traveler of Pier 2 cantilever using strand jacks. The wing and web forms are lowered next as one unit and then relocated to another pier where balanced cantilever construction will resume. (Image courtesy of FIGG).

US-191 Bridge (Fig. 12) provides the main access to Arches National Park across the Colorado River just North of Moab, Utah. This concrete segmental bridge will connect with its

beautiful landscape through its shape, layout, long spans, color, texture, and arching form. The community selected the texture for the piers and barriers as well as other project features

during a day long design charette conducted by FIGG. The bridge was advertised by the Utah Department of Transportation for bids on December 6, 2008.

Owner: Pennsylvania Turnpike Commission

Designer: FIGGContractor: Walsh ConstructionConstruction Engineer: TY Lin InternationalConstruction Engineering Inspection: McTish with FIGGForm Travelers for Cast-in-Place Segments: Schwager Davis, Inc.Post Tensioning Materials: Schwager Davis, Inc.Prepackaged Grout: Sika

I-76 Allegheny River Bridge, Oakmont, Pennsylvania

The construction of the new Allegheny River Bridge for the Pennsylvania Turnpike Commission near Pittsburgh, Pennsylvania has made significant progress. With a 532' main span over the Allegheny River, this will be Pennsylvania’s first long span concrete segmental bridge. Construction of the twin 2,350' structures began in May 2007 and is scheduled for completion in 2010 to accommodate major golf tournaments at the nearby Oakmont Country Club (Fig. 11).

US 191 Bridge over the Colorado River, Moab, Utah

Owner: Utah Department of TransportationDesigner: FIGG

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Figure 13 - Tx28 Girder Shear Test at the University of Texas at Austin.

R E S E A R C H N E W S

In an effort to contribute to the development of a new family of prestressed concrete girders, full-scale Tx-Girders were fabricated and tested in the Phil M. Ferguson Structural Engineering Laboratory of the University of Texas at Austin (Fig. 13). Performance of the new girders was found to be superior to that of previously existing cross sections while allowing for greater bridge span to girder depth ratios. As part of this study, an extensive database of shear test was gathered and examined in depth, resulting in the recommendations presented in this article.

Shear design provisions for segmental box girder bridges included in the AASHTO-LRFD Bridge Design Specifications were used to estimate the shear strength of specimens from the University of Texas Prestressed Concrete Shear Database. Shear strength ratios (Experimental maximum shear divided by the calculated shear strength) were obtained for all specimens using the shear design provisions for segmental

box girder bridges as well as other current shear design provisions.

After examining shear strength estimates from the shear design provisions for segmental box girder bridges, a great degree of conservatism was observed throughout the database. Shear design provisions for segmental box girder bridges were carefully examined. Specifically, the limitation on K = 1 for members in which the tensile stress on the outer most fiber exceeds 0.9 f c

′ (where f c′ is given

in ksi or 6 f c′ when f c

′ is given in psi), introduced with the rational of covering flexure shear related failures, and the limitation on the value of f c

′ to 3.16 for all cases (or 100 when f c

′ is given in psi), regardless of the amount of shear reinforcement provided in the member.

When Ramirez and Breen (1983) first proposed the shear strength equations for segmental box girder bridges found today in the AASHTO-LRFD Bridge Design Specifications, they evaluated a database of shear tests available at that time. Ramirez and Breen (1983) obtained unconservative shear strength estimates for two specimens tested by MacGregor et al. (1960). As a result of this, the limit on K was then introduced and conservative shear strength estimates were obtained for MacGregor et al.’s

(1960) two specimens. Shear strength ratios for these two specimens are presented in Table 1.

Upon re-examining the data from Ramirez and Breen’s (1983) database and examining the University of Texas Prestressed Concrete Shear Database, it was found that for the two specimens in question, all other currently accepted shear design provisions evaluated (except for shear design provisions for segmental box girder bridges) yield unconservative shear strength estimates.

This fact led the researchers to believe that (i) shear design provisions for segmental box girder bridges without the limit on K for members with flexural tension cracks are as conservative as other currently accepted shear design provisions; (ii) Failure of the two specimens tested by MacGregor et al. (1960) was possibly related to an unaccounted phenomenon in order for all design provisions to provide unconservative strength estimates; (iii) Setting a limit for the value of K in order to obtain conservative shear strength estimates for the two mentioned specimens is not justified.

Limiting f c′ to 3.16 (or 100 when

f c′ is given in psi) was meant to cover

an expected decrease in the ultimate shear strength of beams fabricated with

Recommendations for the shear design provisions for segmental box girder bridges of the AASHTO-LRFD Bridge Design Specifications, 4th Edition, 2008 Interim (2008)

Alejandro R. Avendano and Oguzhan Bayrak, University of Texas at Austin

ACI 318-08 AASHTO LRFD (2008 Interim)

SpecimenID

Simple Method

Detailed Method

General Procedure

Simplified Procedure

Segmental Box Girder Bridges

Segmental Box Girder Bridges

(Proposed)

AD.14.37 0.60 0.96 0.60 0.93 1.22 0.61

BD.14.23 0.79 0.84 0.59 0.93 1.49 0.77

Table 1: Shear Strength Ratio for two of MacGregor et al. (1960) specimens.

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high strength concretes. It is believed that given than the shear crack surface in high strength concrete beams is smoother than that of normal strength concrete, the quality of aggregate interlock decreases, resulting in lower ultimate strengths. It is also believed that as shear cracks grow wider, aggregate interlock ceases to contribute to shear strength. The University of Texas Prestressed Concrete Shear Database was further examined in an effort to validate these ideas.

The University of Texas Prestressed Concrete Shear Database contains information from 30 references regarding shear strength of prestressed concrete beams published between 1954 and 2008. A total of 506 tests are included in the database, from which our main focus was devoted to a group of 153 specimens complying with the following criteria:

1. The failure mode is shear related, including specifically: (i) Diagonal web crushing, (ii) Flexure shear, (iii) Diagonal Tension, (iv) Shear

Tension (anchorage failure or rupture of stirrups), (v) Strand Slip/Bond failure, and (vi) Sliding Shear (Horizontal Shear)

2. The overall depth of the member is greater than 12 inches

3. Some transverse reinforcement is included

Items 2 and 3 above were established to exclude test specimens that are not representative of the actual bridge girders. With the increasing availability of shear tests on full-scale specimens, it seems appropriate to statistically evaluate current design provisions using more representative tests. As part of this filtering process, the specimens tested by MacGregor et al. (1960) are not included in our analysis, given than they are only 12 inches deep and have no shear reinforcement.

The limit on K is aimed at providing a similar provision to the Vci and Vcw approach used in AASHTO Standard and LRFD Specifications and ACI 318 by making Vc the lesser of Vci and Vcw. For this reason, the 153 specimens

included in the evaluation database were grouped into 23 specimens governed by flexure-shear (Vci < Vcw) and 130 specimens governed by web-shear (Vcw < Vci). Results of this analysis are shown in Table 2.

Furthermore, if the upper limit of 3.16 on f c

′ is waived for sections with at least the minimum amount of shear reinforcement indicated in the AASHTO-LRFD Bridge Design Specifications, no significant loss of conservativeness was observed as can be seen by comparing columns 3 and 6 of Table 2. In effect, this analysis would imply that the current shear provisions for segmental box girder bridges can be extended to high strength concrete without compromising the conservativeness of the provisions.

The results of this analysis indicate that shear design provisions for segmental box girder bridges are not only conservative but remarkably accurate in the estimation of shear strength when no limit on K is

V

Vcalc

exp Current Provisions

Without limit on K

All Selected Specimens

Specimens where

Vci < Vcw

Specimens where

Vcw < Vci

Without limit on

f c′

Average 2.16 1.78 1.39 1.85 1.75

Std dev 0.66 0.39 0.14 0.37 0.38

COV 0.30 0.22 0.10 0.20 0.22

Unsafe Cases 0 0 0 0 0

Total 153 153 23 130 153

Unsafe % 0.00% 0.0% 0.0% 0.0% 0.0%

φ 0.9 0.9 0.9 0.9 0.9

%SR < φ * 2.8% 1.2% 0.02% 0.5% 1.3%

Table 2: Evaluation of Shear Provisions for Segmental Box Girder Bridges (AASHTO-LRFD Bridge Design Specifications (2008 Interim))

* %SR < φ is the probability of the shear strength being lower than the design strength, taken as ØVn, based on a standard normal probability distribution.

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Figure 14 - Shear Strength Ratio versus concrete compressive strength for 153 tests using shear design provisions for segmental box girder bridges. (a) Current specifications (b) Specifications with proposed changes.

imposed for members with flexural-tension cracks, both for cases governed by flexure-shear or web-shear (Tables 2 and 3).

Figure 14 illustrates the distribution of the Shear Strength Ratio versus concrete strength for the current shear provisions for segmental box girder bridges with and without the limits on K and f c

′ for the 153 tests. It can be observed how the removal of the limits on K and f c

′ results in consistently safe strength estimations without being overly conservative. Additionally, no pronounced trend is observed in Fig. 14, hence, a limit on

f c′ seems unjustified for beams with

at least a minimum amount of shear reinforcement.

In conclusion, it is recommended that:

i For shear design, the stress variable

K shall be given by:

K = 10.0632

2.0+f

f

pc

c'

Where:K = stress variable K shall not be

taken greater than 1.0 for any section where the stress in the extreme tension fiber, calculated on the basis of gross section, due to factored load and effective prestress force after losses exceeds 0.9 f c

′ in tension.

ii The value f c′ is allowed to be

taken greater than 100 psi (or 3.16

(a) f c′ (psi) (b) f c

′ (psi)

ACI 318-08 AASHTO LRFD (2008 Interim)

V

Vcalc

exp

Simple DetailedGeneral Procedure

Simplified Procedure

Segmental Box Girder Bridges

Segmental Box Girder Bridges (Proposed)

Average 1.84 1.42 1.32 1.43 2.16 1.75

Std dev 0.51 0.29 0.31 0.46 0.66 0.38

COV 0.28 0.20 0.23 0.32 0.30 0.22

Unconservative Cases 0 6/153 17/153 16/153 0 0

% Unconservative 0.00% 3.92% 11.11% 10.46% 0.00% 0.00%

Ø 0.75 0.75 0.9 0.9 0.9 0.9

%SR < Ø* 1.6% 1.0% 8.5% 12.3% 2.8% 1.3%

* %SR < Ø is the probability of the shear strength being lower than the design strength, taken as φVn, based on a standard normal probability distribution.

Table 3: Shear Strength Ratio Statistics for Specimens with transverse reinforcement and reinforcement and overall depth greater than 12 in.: 153 Tests

when f c′ is given in ksi) as long as

the requirements for Minimum Transverse Reinforcement from section 5.8.2.5 are satisfied.

The easy-to-use shear design provisions for segmental box girder bridges will be as accurate as or more accurate than other shear design provisions upon implementation of the proposed changes. It is also important to note that the conservative nature of these provisions is not compromised with these proposed changes (Table 3.)

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A M E R I C A NS E G M E N T A L B R I D G EI N S T I T U T E

142 Cimarron Park LoopSuite FBuda, TX 78610

Phone : 512. 523-8214

Fax: 512. 523-8213

e-mail: info@asbi-assoc.org

Web: www.asbi-assoc.org

1

EDITOR: Clifford L. Freyermuth

Biography: Oguzhan Bayrak is Associate Professor at Department of Civil, Environmental

and Architectural Engineering, and holds Charles Elmer Rowe Fellowship in Engineering at the University of Texas at Austin. He serves as Director of the Phil M. Ferguson Structural Engineering Laboratory.

Alejandro Avendano is a research assistant at the University of Texas at Austin. He received his Bachelors in Civil Engineering from the Technological University of Panama and his Masters in Structural Engineering from The University of Texas at Austin. His research interests include the behavior of prestressed concrete elements.

References:1. AASHTO, LRFD Bridge Design Specifications, 4th Edition, 2008 Interim

Revisions, American Association of State Highway and Transportation Officials, Washington, D.C., 2008.

2. ACI Committee 318, Building Code Requirements for Structural Concrete (ACI 318-08), American Concrete Institute, Farmington Hills, MI, 2008.

3. Avendaño, A., Bayrak, O., “Shear Strength and Behavior of Prestressed Concrete Beams”, Technical Report for TxDOT IAC-88-5DD1A003-3, The University of Texas at Austin, Austin, Texas, 2008. 180 pp.

4. MacGregor, J. G., Sozen, M. A., and Siess, C. P., “Effect of Draped Reinforcement on Behavior of Prestressed Concrete Beams,” Journal of the American Concrete Institute, V. 32, No. 6, December 1960, pp. 649-677.

5. Ramirez, J. A., and Breen, J. E., “Experimental Verification of Design Procedures for Shear and Torsion in Reinforced and Prestressed Concrete,” Research Report 248-3, Center of Transportation Research, University of Texas at Austin, Austin, Texas, November 1983.