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Title: ACI’s International Programs, Chapters, and Aspirations

Author(s): Kopczynski

Publication: Web Session

Volume:

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 1/20/2021

Abstract:
Precast prestressed double-tee (DT) girder bridges have been frequently used in South Dakota and the neighboring states especially on local roads. DT bridges are cost-effective and are easy to construct and install. Nevertheless, many of these bridges are deteriorating due to insufficient detailing and environmental conditions. Current AASHTO specifications generally include the bridge superstructure damage into load rating and yet to include the component-level damage in the assessment. A damage-based component-level load rating is needed to successfully estimate the safe capacity of damaged/old DT bridges. To attain this goal, field testing, laboratory testing, and an extensive analytical study were performed. First, two DT bridges (more than 30-yr old) with deteriorated girder-to-girder joints were field tested to determine the live load distribution. Subsequently, two 45-year-old DT girders, one 30-ft (9.14-m) and another 50-ft (15.24-m) long, were extracted from a bridge in Rapid City, SD, and were tested to failure at the Lohr Structures Laboratory at South Dakota State University. The salvaged girders, as received, had extensive damage such as exposure of tendons, loss of stem concrete, and flange concrete spalling. Furthermore, more than 1500 analyses were performed to determine the capacity of DT girders with different damage types and condition states. Finally, based on the experimental and analytical studies, a new method was proposed to load rate damaged DT girder bridges. The presentation highlights the findings of the study and discusses the proposed damaged-based load rating methodology.