The highway transportation network relies on the health and integrity of bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that are less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the bridge response. Many of the bridges are vulnerable to earthquakes, which can result in not only immediate damage but also in potentially lingering economic impact caused by the disruption to traffic and freight mobility. PSU in collaboration with ODOT is currently conducting a seismic vulnerability study of the state’s highway bridge network. The study incorporates FHWA developed risk analysis graphical information system software, which incorporates vast datasets from multi-disciplinary sources including transportation, geotechnical and structural. One of the key components in determining the impact of... View Full Summary

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The highway transportation network relies on the health and integrity of bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that are less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the bridge response. Many of the bridges are vulnerable to earthquakes, which can result in not only immediate damage but also in potentially lingering economic impact caused by the disruption to traffic and freight mobility. PSU in collaboration with ODOT is currently conducting a seismic vulnerability study of the state’s highway bridge network. The study incorporates FHWA developed risk analysis graphical information system software, which incorporates vast datasets from multi-disciplinary sources including transportation, geotechnical and structural. One of the key components in determining the impact of an earthquake on the transportation network is the bridge damage state models represented by fragility functions. The scope of the existing vulnerability study is limited to the software’s default version of the damage state models, which do not specifically include key parameters for the majority of vulnerabilities found in Oregon bridges that consist of girders on seats and bearings with multi-column bents. Since a retrofitted bridge does not constitute a damage free or even collapse free structure, understanding the retrofitted damage states is also crucial in assessing the effectiveness of the retrofit and in evaluating the impact on the transportation network. The main objective of the proposed research is to enhance and expand the scope of the ongoing seismic vulnerability study by developing damage state models for the most deficient bridge types and retrofit measure likely to be encountered in Oregon. The research effort will fully utilize in-place professional relationships from the ongoing seismic vulnerability study. The first phase of the work will consist of identifying the types of bridges that are not included and the retrofit measures most applicable for vulnerabilities in Oregon. A retrofit measure will be chosen based on the prevalence of the vulnerability and the likelihood of implementation. A representative numerical model of the bridge types will be developed. The second phase of the work, planned for the following year and not detailed in this proposal, will concentrate on selected laboratory experiments and numerical model calibration. The developed and calibrated damage state models will be incorporated into the Oregon transportation seismic hazard model that is currently being developed. The proposed research will contribute to an ongoing multi-disciplinary study and is consistent with OTREC theme of healthy communities by addressing transportation issues dealing with sustainable management of transportation infrastructure and safety. The results will have local impact and national significance as the topic addresses the themes of “safety assurance of highway structures for extreme events” and contributes to the “the development and implementation of bridge management systems” for seismic hazard (National Highway R&T Partnership, Highway Research and Technology: The Need for Greater Investment, 2002). The research builds and expand the scope of an existing study, further broadening the impact of the work by continuing to involve ODOT professionals and further strengthening the existing links with academia. Student involvement is currently a significant aspect that will continue to be nurtured throughout.

Portland State University Civil & Environmental Engineering, ODOT Bridge Section

Project Type: Research
Start Date: October 1, 2007
End Date: February 28, 2009
Related Projects: None
Research Area: Healthy Communities