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A Compilation of Research on Seismic Vulnerability of Curved Bridges Using Straight Prestressed Concrete I-girders
Thesis - University Access Only
Master of Science (MS)
Department / School
Civil and Environmental Engineering
Bridge seismic risk assessment tools and procedures have been proposed and implemented by engineers since the 1970’s as concern grew for the vulnerability of bridges to earthquakes. Recently, studies have proposed methods to quantify this risk using fragility analysis based on different damage state levels. Bridges located in the central and southeastern United States (CSUS) have particular vulnerability due to lack of seismic design considerations while still being subjected to potentially moderate seismic activity. Bridges built in this region before the 1990’s did not consider seismic detailing during design. Only recently have bridges in the more susceptible regions, such as around the New-Madrid fault, begun incorporating seismic design considerations. This leaves many bridges vulnerable to seismic damage including older bridges within fault zones as well as new bridges located outside of fault zones but within range of receiving potentially damaging ground motions. Curved precast pre-stressed concrete (PSC) I-girder bridges are a low cost and efficient design to accomplish complex highway geometries. An example would be an interstate highway interchange or an approach ramp to a freeway. By using conventional components and established construction techniques, this type of bridge is a viable option for various highway projects. Meanwhile, these bridges have been used in the past to satisfy design and site requirements all over the United States for many years, both in seismic and non-seismic regions. Specifically, curved PSC I-girder bridges use straight pre-stressed-precast concrete girders with a curved cast-in-place deck on top. The result is that beams are chorded along the curve of the deck, supported on each end by either an abutment or bent. Diaphragms are cast-in-place over bent supports between girder ends to create continuity for live loads. Abutments are typically seat-type to allow for the asymmetrical effects of curvature from expansion and construction of the superstructure. This thesis is composed of three research papers, each presented as separate chapters, which investigate various aspects of the seismic analysis and vulnerability of curved PSC I-girder bridges. Chapter one investigates the seismic response of a single span curved PSC bridge under various ground motion intensities along with possible retrofit and/or new construction components using shape memory alloys (SMA’s). Chapter two compares and contrasts two separate 3D modeling techniques for a representative single span curved PSC I-girder bridge subjected to ground motions of varying intensity. After determining the most efficient modeling and analysis technique, fragility curves are constructed for a suite of 15 single span curved bridges and results are compared to past studies. Finally, chapter three investigates seismic vulnerability and resiliency of a suite of 87 multispan and single span curved PSC I-girder bridges. Ground motions with a wide range of intensities are applied to each bridge. Seismic fragility analysis is used to determine bridge sensitivity to various parameters such as span length and curvature or bridge width.
Library of Congress Subject Headings
Bridges -- Earthquake effects -- Testing Prestressed concrete bridges -- Earthquake effects -- Testing Prestressed concrete beams -- Earthquake effects Girders -- Earthquake effects Reinforced concrete construction Earthquake engineering Earthquake resistant design
Includes bibliographical references (pages 139-146)
Number of Pages
South Dakota State University
Rogers, Luke P., "A Compilation of Research on Seismic Vulnerability of Curved Bridges Using Straight Prestressed Concrete I-girders" (2015). Electronic Theses and Dissertations. 1895.