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STRUCTURES TEAM

PCEF Meeting Minutes
February 5, 2007
Atlantic City, New Jersey

Meeting convened at 1:00 PM.

I. Approval of Minutes from August 29, 2006 meeting

A. Bob Horwhat from PennDOT moved to accept the minutes.
B. Allan Derr from New Enterprise Stone & Lime seconded the motion.

II. Central Atlantic Bridge Associates (CABA) Presentation - Hank Bonstedt, PCAP (attached)

A. Associated with PCI. Supports the MD, PA and VA concrete conferences, the Pittsburgh International Bridge conference, and AASHTO T-10 committee activities. Review State DOT standards for p/s concrete.

B. Also receive input from non-members

C. Looking to build industry alliances, present at exhibits, and emphasize knowledge transfer and education.

D. PCI Bridge Design Manual is their working document.

E. Technical Developments under Evaluation.

1. Product improvement and non-traditional materials.
2. Using strands instead of rebar for positive moment connections.
2a.There may be problems with coating the strands.
3. P/S concrete approach slabs
4. High fly ash cements (50% substitution for Type I)
5. Hydrophobic admixturers

F. Suggestions from others.

1. CABAbridges.org

III. Design Parameters and Standardization Committee ~ Charles Pettie, VDOT

A. Electronic files of PCEF Bulb-T details.

1. All information can be referenced from the same sheet.
2. Everything can be put on disc for distribution, or linked to a website.
3. Names of details are defined by the web and top flange.
3a. One issue might be that the total depth varies when you bring in the top flange.
3b. Charles mentioned he doesn’t have sections with varying depth.

B. End crack control.

1. Route 5 and Route 33 are ongoing pilot projects.
2. Major issues were the shear equations that have to be modified for the ends of the beam (more steel). The plan is to come up with a universal standard.
3. Cracks are usually horizontal across the beam.
4. Allan Derr mentioned that AASHTO I-beams with 8” webs only had minor shear cracks at the ends.
5. One previous problem with BT72’s was that the beams were hollow at the ends.
6. Epoxy injection can be used to temporarily mitigate cracking problems.

IV. Presentation on FHWA Technical Working Group for HPC Research Program - Lou Triandafilou, FHWA Resource Center (attached)

A. This group is providing oversight to the FHWA program for research, deployment and technology transfer (about $4 million per year from SAFETEA- LU). Group consists of FHWA, State DOT, academia, industry and consultant.

B. Research elements include lightweight concrete, HPC bridge decks, uniform extension of LRFD shear provisions and NDE methods for detecting voids in p/t ducts.

C. Development and deployment elements include a manual for HPC practice, integral abutment/jointless bridges, HPC design and rating examples, integration through automation, evaluating and extending the service life of p/t bridges, and a design guide for corrosion-free HPC p/s concrete box beams.

D. Technology transfer elements include conferences, newsletters, showcases, seminars, workshops and training courses.

E. A separate discussion was held regarding State DOT policies for supporting deck finishing machines during concrete placement. Offsetting the finishing machine beyond the outside edge of deck can put undesirable eccentric loads on the exterior girder. However, supporting the machine on top of the exterior girder flange results in undesirable disturbing and refinishing of the concrete in order to remove rails.

1. VDOT uses the rail system beyond the edge of deck with no problems, unless dealing with steel girders.

2. MD puts the supports on exterior formwork and the steel girders sometimes twist.

3. DE supports the finishing machine on exterior formwork beyond the edge of deck.

4. PA also supports it on the exterior formwork and the overhang is limited to ½ the girder spacing. Braces are supported by bottom flange and not mid-depth of web.

5. NJ leaves it to the contractor’s discretion on where to place supports.

6. WV specifications require that the deck be finished by mechanical means, with the machine supported on the fascia girder. No problems have been reported with this method. They also use TAEG software from Kansas DOT that can calculate flange rotation.

V. Follow up on HPC Technology Deployment Team Activities ~ Lou Triandafilou, FHWA

A. A separate HPC technology delivery team consisting of FHWA, State DOTs,
industry and academia has conducted seminars for States, covering issues related to materials and construction, especially mitigating deck cracking.

B. This group reviews specifications and research reports in order to optimize mix designs and deal with ASR issues.

C. The group has produced and HPC guide for structural designers, which it plans to start updating this year.

D. The Team has conducted a 2003-04 national survey of State DOT implementation of HPC. The survey was updated last year, and results have been compiled for distribution in the near future.

E. The Team also maintains a HPC Community of Practice website which allows the free exchange of questions and answers related to HPC. The site also contains a list of references broken down by focus area, and a section for works in progress.

F. Finally, the Team will also assist the HPC technical working group in the oversight areas described under section IV above.

VI. Materials & Construction QC/QA Subcommittee ~ Bob Horwhat, PennDOT

A. Regarding quality control, the idea is to submit a plan to the States, to be signed off by representatives, and have one unified set of guidelines.

B. SCC: same plan as QC plan. There should be one setup with a mix qualification test. However, whoever has formal SCC specifications has to be mentioned as well (e.g., New York).

1. Some producers vibrate SCC, some don’t think it’s necessary.
2. Another issue is air content: most prefer one continuous pour, borrowed from ASTM specifications.
3. The SCC Matrix is finalized and will be sent out for comments to the entire membership, along with the meeting minutes.

C. The subcommittee will begin working on beam repair procedures using SCC, with the goal of adding an approved document as another appendix to the PCEF-adopted materials control manual. PCI repair guidelines will be used as a starting point in this effort. This effort will also lead to guidelines for precast members

D. Jose Lopez will be the new contact person for NJ on this subcommittee.

VII. Feedback on Participating in DEF Pooled Fund Study ~ Paul Finnerty, MDSHA

A. DEF (delayed ettringite formation).

1. 1st phase: able to create it in the lab.
2. Determined that it exists in cast-in-place concrete as well as precast shapes.

B. Second phase increased the number of structures in the study and tried to arrest the formation of DEF in place – 90% complete.

1. One product used to penetrate the concrete was called Chimney Saver.
2. Lithium was not helpful in retarding DEF.
3. Reactive aggregates were found to generate DEF, along with certain types of cement.
4. PA is launching a pilot project, and Paul offered to share the findings of the second phase.
5. A Phase III of the study will look at different climates and different types of sands used in DEF-affected structures.
6. Study initially launched in TX; DEF has become a national phenomenon.

VIII. Elastomeric Bearings Research Study ~ Dr. C.C. Fu, University of Maryland

A. Tasks were to identify problems, monitor deterioration, and generate a summary. Looked at a total of 130-150 bearings.

B. The sample size was not evenly distributed among different bearing types.

C. Lengths, widths, and heights of bearing varied greatly. Since only 30’ was the maximum pier height viewed, study did not see the effects of height.

D. Many deterioration modes were chosen, including slip, aging, and failure

E. “Bulging” was the most frequent deterioration mode (42 examples).

F. AASHTO made major changes to design ~ they started to incorporate material properties in design, and announced that the shear modulus is most important property to consider. Study noted that design Method B was an improvement over Method A.

G. Pontis rating criteria in Maryland is 1,2,3,4.

H. Since an NCHRP by Dr. Stanton already recommends design specifications, this study is purely to determine where Maryland stands according to AASHTO deterioration criteria.

I. Bearings with shape factors of 4, 5, 6, or 7 are resulting in good designs.

J. Bearings with shape factors of 3,4,8, or 9 show advanced deterioration.

K. Shape factors are based on geometry.

L. Data also shows that compressive stress increases with thickness.

IX. Feedback on Tall Pier and Elastomeric Bearing Design

Maryland does not see many integral bridge abutments or tall pier designs.

X. Other

A. Protective methods on overhead P/S concrete girders from impact.

1. TX has a detail, but not popular; they use an angle attached to the side of the beam, not embedded in it. It assumes knowing where the truck is going to hit, and it assumes the force is distributed over a wide area.

B. Galvanized P/S strands.

1. In WV, 3 layers of protective systems were sought for a major structure. A request to use galvanizing was making transverse P/T in the deck too expensive. There was also a concern that zinc accelerated corrosion. The solution was to design precast, p/s HPC decks with zero tension, increased cover, and an overlay.

2. Strands should not be in direct contact with the concrete deck.

3. Troy Jenkins noted that epoxy coated strands worked fine for P/T; they were problematic when used in a pretensioned application.

4. None of the States noted experience with using galvanized strands. Other concerns reported in the literature included possible strength reduction, hydrogen embrittlement, and the release of hydrogen gas.

C. A guide to PCEF BT sections was handed out for comment, and there’s going to be a cover sheet on each one to and be put on disc.

D. There was a concern over new LRFD provisions that established a minimum girder age before making continuity connections. The AASHTO 4th edition of the specifications suggests 90 days. Some states will start putting this time provision in their contracts. Some States design for simple spans but build for
continuity.

E. There seemed to be no problems from any states regarding concrete overlay durability on prestressed concrete box beams, deck panels or voided slabs.

Meeting was adjourned at 5:00 PM.

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