|dc.description.abstract||This research study focuses on evaluating the design of HSC prestressed bridge
girders. Specifically there were three major objectives. First, to determine the current state of practice for the design of HSC prestressed bridge girders. Second, to evaluate the controlling limit states for the design of HSC prestressed bridge girders and identify areas where some economy in design may be gained. Third, to conduct a preliminary assessment of the impact of raising critical design criteria with an objective of increasing the economy and potential span length of HSC prestressed girders.
The first objective was accomplished through a literature search and survey. The
literature search included review of design criteria for both the AASHTO Standard and LRFD Specifications. Review of relevant case studies of the performance of HSC
prestressed bridge girders, as well all as of important design parameters for HSC were carried out. In addition, a survey was conducted to gather information and document critical aspect of current design practices for HSC prestressed bridges
The second objective was accomplished by conducting a parametric study for
single span HSC prestressed bridge girders to mainly investigate the controlling limit
states for both the AASHTO Standard (2002) and LRFD (2002) Specifications.
AASHTO Type IV and Texas U54 girder sections were considered. The effects of
changes in concrete strength, strand diameter, girder spacing and span length were
Based on the results from the parametric study, the limiting design criteria for
HSC prestressed U54 and Type IV girders using both the AASHTO Standard and LRFD Specifications for Highway Bridges were evaluated. Critical areas where some economy in design may be gained were identified.
The third research objective was accomplished by evaluating the impact of
raising the allowable tensile stress for service conditions. This stress limit was selected for further study based on the current limit for uncracked sections provided by the ACI 318 code (2002) and the limit used for a specific case study bridge (Ralls 1995). Recommendations for improving some critical areas of current bridge designs, as well as for increasing bridge span lengths, are given.||en_US