Prestressed Concrete Girder Bridges Using Large 0.7 Inch Strands

The National Bridge Inventory (NBI) includes more
than 600,000 bridges within the United States of America.
Prestressed concrete girder bridges represent one of the most widely
used bridge systems. The majority of these girder bridges were
constructed using 0.5 and 0.6 inch diameter strands. The main
impediments to using larger strand diameters are: 1) lack of prestress
bed capacities, 2) lack of structural knowledge regarding the transfer
and development length of larger strands, and 3) the possibility of
developing wider end zone cracks upon strand release.
This paper presents a study about using 0.7 inch strands in girder
fabrication. Transfer and development length were evaluated, and
girders were fabricated using 0.7 inch strands at different spacings.
Results showed that 0.7 inch strands can be used at 2.0 inch spacing
without violating the AASHTO LRFD Specifications, while attaining
superior performance in shear and flexure.

• Amin Akhnoukh

• 0.7 inch strands
• prestress
• I-girders
• bridges

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Superstructure Systems&rdquo;, A Thesis, University of Nebraska-Lincoln,
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[2] Aashto LRFD Bridge Design Specifications for Highway Bridges, Third
Edition, American Association of State Highway and Transportation
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[3] Astm A497, &ldquo;Standard Specification for Steel Welded Wire
Reinforcement, Deformed, for Concrete&rdquo;, Annual Book of ASTM
Standards, American Society for Testing and Materials, 2005.
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Pretensioned Bridge Girders Cast with Self-Consolidating Concrete&rdquo;,
PCI Journal, Nov.-Dec., 2005
[5] Akhnoukh, A.K., &ldquo;Development of High Performance
Precast/Prestressed Bridge Girders&rdquo; A Dissertation, University of
Nebraska-Lincoln, 2008</p>