The purpose of the research study is to conduct an investigation to understand the performance of a relatively new type of bridge construction that involves prestressed (post-tensioned) steel-concrete composite bridge members. Strictly speaking, the technical and economical advantages of this type of structure have been understood for several decades. However, the application of this concept to practice is still very limited due to difficulties associated with the post-tensioning anchorage. The study was thus intended to explore the mechanical behavior of such construction. Both the short-term and long-term bridge performance were evaluated in this study.

The investigation included experimental as well as analytical evaluations of the structural behavior. The experimental part involved a series of field measurements of a newly constructed steel-concrete composite bridge which was post-tensioned with high-strength steel tendons. This bridge, which is part of the I-90 Indiana Toll Road, is located in Elkhart County, Indiana. Strain distributions in the composite girders and the elongation of a selected post-tensioning tendon were measured at certain crucial phases of construction. The field monitoring was periodically conducted over a period of about one year after the post-tensioning operation. Analytical solutions were developed to evaluate the structural response due to various types of instantaneous loads, temperature effects and time-dependent factors. The validity and effectiveness of the analytical model were examined by comparing the calculated results with the data collected from the field. Further prediction of the long-term structural response was also performed based on the proposed methodology. A cost comparison for the structural components between the Elkhart post-tensioned bridge and a nearby conventional steel bridge was also conducted.

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post-tensioning, tendon, creep, shrinkage, relaxation, prestress losses, transformed sections, SPR-2151

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Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, IN

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