Advantages of Large Strands in Precast/Prestressed Concrete Highway Application

The objective of this research is to investigate the
advantages of using large-diameter 0.7 inch prestressing strands in
pretention applications. The advantages of large-diameter strands are
mainly beneficial in the heavy construction applications. Bridges and
tunnels are subjected to a higher daily traffic with an exponential
increase in trucks ultimate weight, which raise the demand for higher
structural capacity of bridges and tunnels. In this research, precast
prestressed I-girders were considered as a case study. Flexure
capacities of girders fabricated using 0.7 inch strands and different
concrete strengths were calculated and compared to capacities of 0.6
inch strands girders fabricated using equivalent concrete strength.
The effect of bridge deck concrete strength on composite deck-girder
section capacity was investigated due to its possible effect on final
section capacity. Finally, a comparison was made to compare the
bridge cross-section of girders designed using regular 0.6 inch strands
and the large-diameter 0.7 inch. The research findings showed that
structural advantages of 0.7 inch strands allow for using fewer bridge
girders, reduced material quantity, and light-weight members. The
structural advantages of 0.7 inch strands are maximized when high
strength concrete (HSC) are used in girder fabrication, and concrete
of minimum 5ksi compressive strength is used in pouring bridge
decks. The use of 0.7 inch strands in bridge industry can partially
contribute to the improvement of bridge conditions, minimize
construction cost, and reduce the construction duration of the project.

• Amin Akhnoukh

• 0.7 Inch Strands
• I-Girders
• Pretension
• Flexure Capacity

<p>[1] Reiser, N.P, &ldquo;Innovative Reinforced/Prestressed Concrete Bridge
Superstructure Systems,&rdquo; A Thesis, University of Nebraska-Lincoln,
Nebraska, 2007
[2] AASHTO, LRFD Bridge Design Specifications for Highway Bridges,
Third Edition, American Association of State Highway and
Transportation Officials, Washington, DC, 2006
[3] Vedivelu, J, and Ma, Z., &ldquo;Potential Impact of 0.7 inch Strands on
Precast/Prestressed Concrete Bridge I-Girders: Spacing of Large
Diameter Strands,&rdquo; Proceedings of the Concrete Bridge Conference,
Saint Louis, Missouri, 2008
[4] Akhnoukh, A.K., &ldquo;Development of High Performance
Precast/Prestressed Bridge Girders,&rdquo; A Dissertation,,University of
Nebraska-Lincoln, Nebraska, 2008</p>