Advantages of Large Strands in Precast/Prestressed Concrete Highway Application

Authors: Amin Akhnoukh

Abstract:

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.

Keywords: 0.7 Inch Strands, I-Girders, Pretension, Flexure Capacity

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1087554

References:

[1] Reiser, N.P, “Innovative Reinforced/Prestressed Concrete Bridge Superstructure Systems,” 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., “Potential Impact of 0.7 inch Strands on Precast/Prestressed Concrete Bridge I-Girders: Spacing of Large Diameter Strands,” Proceedings of the Concrete Bridge Conference, Saint Louis, Missouri, 2008
[4] Akhnoukh, A.K., “Development of High Performance Precast/Prestressed Bridge Girders,” A Dissertation,,University of Nebraska-Lincoln, Nebraska, 2008