The main objective of this study was evaluate feasible alternatives to the current AASHTO bridge girders used in Indiana. This evaluation included precast pretensioned bridge girders for spans from 30 to 130 feet with girder spacing between 5 and 10 feet up to 12 feet for the longer spans. Other criteria included girder design concrete compressive strengths up to 7000 psi, 8” total concrete deck thickness with design strength of 4000 psi, grade 60 steel for slab reinforcement and stirrups and ½” special grade 270 low-relaxation strand for prestressing steel. Post-tensioning and pretensioned box girders were outside the scope of the study.

Approximately 100 alternate sections were received from surveys sent to various department of transportation, consultants, and precasters in the United States. The girder cross sections were then evaluated for their structural efficiency and c ost effectiveness. This was done using the computer program, PCBM, developed by Professor Robert H. Lee at Purdue University and currently used by INDOT.

The AASHTO I, II, and III girders were found to be economical for spans 30 to 70 feet. No alternate sections were therefore recommended in this span range. In the range from 70 to 90 feet the Illinois 54” section is considered the most economical. This section is currently being used as the only alternate section in Indiana. Other alternate sections were found to be more economical for spans over 90 feet. The Kentucky Bulb Tees were recommended for use in spans from 90 to 130 feet to provide considerable savings over the standard AASHTO girders. This would result in a savings of as much as 20 to 25 percent of the bridge superstructure for the longer spans.

Design Aids were created fro these Kentucky Bulb Tees as well as for the AASHTO standards and the Illinois 54” sections. The use of these sections is supported by this research study and recommended to INDOT. Adopting these alternate sections would result in considerable savings in Indiana’s bridge construction.

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Performing Organization

Indiana Department of Transportation and Federal Highway Administration

Publisher Place

West Lafayette, IN

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