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• 1. [Image] Seismicity Report on the Adak Island Project, Aleutian Islands, Alaska

  	In order to evaluate the geothermal potential of a project area on Adak Island, Aleutian Islands, Alaska, a high gain (40-750K), high frequency (5-30hz) microseismic network was operated for a period of ...
  	Citation × Citation Citation Abstract Copy Title: Seismicity Report on the Adak Island Project, Aleutian Islands, Alaska Author: Micro Geophysics Corporation Year: 1975 In order to evaluate the geothermal potential of a project area on Adak Island, Aleutian Islands, Alaska, a high gain (40-750K), high frequency (5-30hz) microseismic network was operated for a period of ten days in late October, 1974. The detection threshold determined from the recurrence curve was found to be below magnitude 0.0. Over 35 local events (S-P time less than four seconds) were detected, of which 26 events can be associated with a postulated fault in Andrew Bay near Mount Adagdak on the north side of Adak Island. First motion studies indicate that this fault is a right-lateral strike-slip fault with a small thrust component. Temporal and spatial variations of Poisson's Ratio within the interpreted fault zone (derived from velocity ratios and Wadati diagrams) have led to the derivation of a theoretical model of a dilatant region near Mount Adagdak. This region is interpreted as having the largest potential of the area surveyed for producing commercial earth steam Title: Seismicity Report on the Adak Island Project, Aleutian Islands, Alaska Author: Micro Geophysics Corporation Year: 1975 In order to evaluate the geothermal potential of a project area on Adak Island, Aleutian Islands, Alaska, a high gain (40-750K), high frequency (5-30hz) microseismic network was operated for a period of ten days in late October, 1974. The detection threshold determined from the recurrence curve was found to be below magnitude 0.0. Over 35 local events (S-P time less than four seconds) were detected, of which 26 events can be associated with a postulated fault in Andrew Bay near Mount Adagdak on the north side of Adak Island. First motion studies indicate that this fault is a right-lateral strike-slip fault with a small thrust component. Temporal and spatial variations of Poisson's Ratio within the interpreted fault zone (derived from velocity ratios and Wadati diagrams) have led to the derivation of a theoretical model of a dilatant region near Mount Adagdak. This region is interpreted as having the largest potential of the area surveyed for producing commercial earth steam Close

• 2. [Image] Volcano and earthquake hazards in the Crater Lake Region, Oregon: open file report 97-487

  	ill., maps; Folded map in back cover; Includes bibliographical references ( p. 27-30) and glossary; Report accompanied by: Volcano hazard zones, volcanic vents, faults in the Crater Lake Region, Oregon ...
  	Citation × Citation Citation Abstract Copy Title: Volcano and earthquake hazards in the Crater Lake Region, Oregon: open file report 97-487 Author: Bacon, Charles R. Year: 1997, 2008 ill., maps; Folded map in back cover; Includes bibliographical references ( p. 27-30) and glossary; Report accompanied by: Volcano hazard zones, volcanic vents, faults in the Crater Lake Region, Oregon [map] Title: Volcano and earthquake hazards in the Crater Lake Region, Oregon: open file report 97-487 Author: Bacon, Charles R. Year: 1997, 2008 ill., maps; Folded map in back cover; Includes bibliographical references ( p. 27-30) and glossary; Report accompanied by: Volcano hazard zones, volcanic vents, faults in the Crater Lake Region, Oregon [map] Close

• 3. [Image] Cascadia : a quarterly publication of the Oregon Department of Geology & Mineral Industries, volume 2, number 1 (Winter/Spring 2002)

  	Water and geology: how does geology control where you find and how you use water? / Roddey, James -- Through the eyes of the state geologist / Beaulieu, John D. -- What is groundwater? -- Geology and groundwater ...
  	Citation × Citation Citation Abstract Copy Title: Cascadia : a quarterly publication of the Oregon Department of Geology & Mineral Industries, volume 2, number 1 (Winter/Spring 2002) Author: Oregon. Dept. of Geology and Mineral Industries Year: 2002, 2005 Water and geology: how does geology control where you find and how you use water? / Roddey, James -- Through the eyes of the state geologist / Beaulieu, John D. -- What is groundwater? -- Geology and groundwater -- Who owns and manages Oregon's water? -- Recent geologic efforts related to groundwater -- A groundwater case study: Catherine Creek and the Upper Grande Ronde Valley -- McKenzie - Willamette River confluence project Title: Cascadia : a quarterly publication of the Oregon Department of Geology & Mineral Industries, volume 2, number 1 (Winter/Spring 2002) Author: Oregon. Dept. of Geology and Mineral Industries Year: 2002, 2005 Water and geology: how does geology control where you find and how you use water? / Roddey, James -- Through the eyes of the state geologist / Beaulieu, John D. -- What is groundwater? -- Geology and groundwater -- Who owns and manages Oregon's water? -- Recent geologic efforts related to groundwater -- A groundwater case study: Catherine Creek and the Upper Grande Ronde Valley -- McKenzie - Willamette River confluence project Close

• 4. [Image] Oregon Plan for Salmon and Watersheds biennial report, 2005-2007

  	The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing ...
  	Citation × Citation Citation Abstract Copy Title: Oregon Plan for Salmon and Watersheds biennial report, 2005-2007 Author: Oregon Watershed Enhancement Board Year: 2006, 2007 The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing efforts of people throughout Oregon to improve and protect clean water and recover and maintain healthy populations offish and wildlife in our watersheds. The Oregon Plan is unique because it engages communities in the restoration and long-term stewardship of their watersheds. This extraordinary effort encourages local partnerships and voluntary actions to improve the conditions of our watersheds. Over the years, these actions have made Oregon a national leader in local cooperative conservation. This report collects project and condition data, voluntary private lands restoration information, and agency program accomplishments under the Oregon Plan. Consistent with the past two reports, this document continues to provide specific data on each of the state's fifteen reporting basins. A new element to this report is the inclusion of stories about the people, partnerships, and on-the-ground projects that are benefiting watersheds and communities across the state. Thanks to the many Oregon Plan partners who contributed to this report. Thomas M. Byler Executive Director Oregon Watershed Enhancement Board Title: Oregon Plan for Salmon and Watersheds biennial report, 2005-2007 Author: Oregon Watershed Enhancement Board Year: 2006, 2007 The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing efforts of people throughout Oregon to improve and protect clean water and recover and maintain healthy populations offish and wildlife in our watersheds. The Oregon Plan is unique because it engages communities in the restoration and long-term stewardship of their watersheds. This extraordinary effort encourages local partnerships and voluntary actions to improve the conditions of our watersheds. Over the years, these actions have made Oregon a national leader in local cooperative conservation. This report collects project and condition data, voluntary private lands restoration information, and agency program accomplishments under the Oregon Plan. Consistent with the past two reports, this document continues to provide specific data on each of the state's fifteen reporting basins. A new element to this report is the inclusion of stories about the people, partnerships, and on-the-ground projects that are benefiting watersheds and communities across the state. Thanks to the many Oregon Plan partners who contributed to this report. Thomas M. Byler Executive Director Oregon Watershed Enhancement Board Close

• 5. [Article] Melting in the Mantle Wedge: Quantifying the Effects of Crustal Morphology and Viscous Decoupling on Melt Production with Application to the Cascadia Subduction Zone

  Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting ...

  Citation × Citation Citation Abstract Copy Title: Melting in the Mantle Wedge: Quantifying the Effects of Crustal Morphology and Viscous Decoupling on Melt Production with Application to the Cascadia Subduction Zone Author: Yang, Jiaming Year: 2017 Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting and decompression melting due to upward flow. The distribution of melting is sensitive to temperature, the pattern of flow, and the pressure in the mantle wedge. The arc front is the surface manifestation of partial melting in the mantle wedge and is characterized by a narrow chain of active volcanoes that migrate in time. The conventional interpretation is that changes in slab dip angle lead to changes in the arc front position relative to the trench. We explore an alternative hypothesis: evolution of the overlying plate, specifically thickening of the arc root, causes arc front migration. We investigate the effects of varying crustal morphology and viscous decoupling of the shallow slab-mantle interface on melt production using 2D numerical models involving a stationary overriding plate, a subducting plate with prescribed motion, and a dynamic mantle wedge. Melt production is quantified using a hydrous melting parameterization. We conclude: 1) Localized lithospheric thickening shifts the locus of melt production trenchward while thinning shifts melting landward. 2) Inclined LAB topography modulates the asthenospheric flow field, producing a narrow, well-defined arc front. 3) Thickening of the overriding plate exerts increased torque on the slab, favoring shallowing of the dip angle. 4) Viscous decoupling produces a cold, stagnant forearc mantle but promotes arc front melting due to reduction in the radius of corner flow, leading to higher temperatures at the coupling/decoupling transition. Title: Melting in the Mantle Wedge: Quantifying the Effects of Crustal Morphology and Viscous Decoupling on Melt Production with Application to the Cascadia Subduction Zone Author: Yang, Jiaming Year: 2017 Arc magmatism is sustained by the complex interactions between the subducting slab, the overriding plate, and the mantle wedge. Partial melting of mantle peridotite is achieved by fluid-induced flux melting and decompression melting due to upward flow. The distribution of melting is sensitive to temperature, the pattern of flow, and the pressure in the mantle wedge. The arc front is the surface manifestation of partial melting in the mantle wedge and is characterized by a narrow chain of active volcanoes that migrate in time. The conventional interpretation is that changes in slab dip angle lead to changes in the arc front position relative to the trench. We explore an alternative hypothesis: evolution of the overlying plate, specifically thickening of the arc root, causes arc front migration. We investigate the effects of varying crustal morphology and viscous decoupling of the shallow slab-mantle interface on melt production using 2D numerical models involving a stationary overriding plate, a subducting plate with prescribed motion, and a dynamic mantle wedge. Melt production is quantified using a hydrous melting parameterization. We conclude: 1) Localized lithospheric thickening shifts the locus of melt production trenchward while thinning shifts melting landward. 2) Inclined LAB topography modulates the asthenospheric flow field, producing a narrow, well-defined arc front. 3) Thickening of the overriding plate exerts increased torque on the slab, favoring shallowing of the dip angle. 4) Viscous decoupling produces a cold, stagnant forearc mantle but promotes arc front melting due to reduction in the radius of corner flow, leading to higher temperatures at the coupling/decoupling transition. Close

• 6. [Article] Links from Mantle to Microbe at the Lau Integrated Study Site: Insights from a Back-Arc Spreading Center

  The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical ...

  Citation × Citation Citation Abstract Copy Title: Links from Mantle to Microbe at the Lau Integrated Study Site: Insights from a Back-Arc Spreading Center Author: Tivey, Margaret K., Becker, Erin, Beinart, Roxanne, Fisher, Charles R., Girguis, Peter, Langmuir, Charles H., Michael, Peter J., Reysenbach, Anna-Louise Year: 2012 The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical province distinct from those of eastern Pacific and mid-Atlantic ridges, and crustal compositions along the ridge lie outside the range of mid-ocean ridge crustal compositions. The Lau ISS is located above a subduction zone, at an oblique angle. The underlying mantle receives water and other elements derived from the downgoing lithospheric slab, with an increase in slab influence from north to south. Water lowers the mantle melting temperature and leads to greater melt production where the water flux is greater, and to distinctive regional-scale gradients along the ridge. There are deeper faulted axial valleys with basaltic volcanism in the north and inflated axial highs with andesites in the south. Differences in igneous rock composition and release of magmatic volatiles affect compositions of vent fluids and deposits. Differences in vent fluid compositions and small-scale diffuse-flow regimes correlate with regional-scale patterns in microbial and megafaunal distributions. The interdisciplinary research effort at the Lau ISS has successfully identified linkages between subsurface processes and deep-sea biological communities, from mantle to microbe to megafauna. Title: Links from Mantle to Microbe at the Lau Integrated Study Site: Insights from a Back-Arc Spreading Center Author: Tivey, Margaret K., Becker, Erin, Beinart, Roxanne, Fisher, Charles R., Girguis, Peter, Langmuir, Charles H., Michael, Peter J., Reysenbach, Anna-Louise Year: 2012 The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical province distinct from those of eastern Pacific and mid-Atlantic ridges, and crustal compositions along the ridge lie outside the range of mid-ocean ridge crustal compositions. The Lau ISS is located above a subduction zone, at an oblique angle. The underlying mantle receives water and other elements derived from the downgoing lithospheric slab, with an increase in slab influence from north to south. Water lowers the mantle melting temperature and leads to greater melt production where the water flux is greater, and to distinctive regional-scale gradients along the ridge. There are deeper faulted axial valleys with basaltic volcanism in the north and inflated axial highs with andesites in the south. Differences in igneous rock composition and release of magmatic volatiles affect compositions of vent fluids and deposits. Differences in vent fluid compositions and small-scale diffuse-flow regimes correlate with regional-scale patterns in microbial and megafaunal distributions. The interdisciplinary research effort at the Lau ISS has successfully identified linkages between subsurface processes and deep-sea biological communities, from mantle to microbe to megafauna. Close

• 7. [Article] Seismic Hazard Assessment of Oregon Highway Truck Routes

  This research project developed a seismic risk assessment model along the major truck routes in Oregon. The study had adopted federally developed software tools called Risk for Earthquake Damage to Roadway ...

  Citation × Citation Citation Abstract Copy Title: Seismic Hazard Assessment of Oregon Highway Truck Routes Author: Dusicka, Peter, Mehary, Selamawit Tesfayesus Year: 2012 This research project developed a seismic risk assessment model along the major truck routes in Oregon. The study had adopted federally developed software tools called Risk for Earthquake Damage to Roadway Systems (REDARS2) and HAZUS-MH. The model was the first time REDARS2 has been adopted and used in research outside of the original development team, presenting a number of unique challenges. The development of the model was a complex, intensive process that required a significant research effort, manipulation and adjustment of data. Furthermore, limitations of the software tools themselves had been identified that prevented the inclusion of important aspects such as liquefaction induced damage and refinement of the transportation network. The main objective of this research were to refine the data from a first generation of the model to more realistically represent the bridge inventory, to address the seismicity of the Pacific Northwest, conduct sensitivity analyses of soil data on the analyses results and develop a seismic network model of Oregon bridges for purposes of assessing the seismic vulnerability of roadway segments. The first generation model relied on default settings within the program to determine the economic loss due to repair and replacement of damaged bridges. The assumptions used in the analyses have been reviewed and Oregon specific data was incorporated for the model. The largest earthquake now considered to be at a highest level of probability in the Pacific Northwest is a subduction zone earthquake. The major shortcoming of REDARS2 is its inability to incorporate the subduction zone attenuation relationship into the analysis. To incorporate that capability into the model, shakemaps were developed by USGS for Cascadia subduction zone scenario events and incorporated as the demand on the refined model. Analyses of the transportation network incorporating bridge routes and post processing of the data with input from Oregon DOT bridge engineers resulted in recommendations toward bridge route priority strategies. The majority of the bridges that indicated the possibility of damage were types associated with multi-column bents, simply-supported concrete superstructures and simply-supported steel superstructures. Of the major highway routes that were considered, I-405, section of I-5 (from Multnomah to Clackamas Counties), I-84, I-205 and US-101 were the top five on the preliminary priority for seismic retrofit. These routes need to be analyzed more and advanced cost-benefit investigations should be done before retrofit decisions are made. Title: Seismic Hazard Assessment of Oregon Highway Truck Routes Author: Dusicka, Peter, Mehary, Selamawit Tesfayesus Year: 2012 This research project developed a seismic risk assessment model along the major truck routes in Oregon. The study had adopted federally developed software tools called Risk for Earthquake Damage to Roadway Systems (REDARS2) and HAZUS-MH. The model was the first time REDARS2 has been adopted and used in research outside of the original development team, presenting a number of unique challenges. The development of the model was a complex, intensive process that required a significant research effort, manipulation and adjustment of data. Furthermore, limitations of the software tools themselves had been identified that prevented the inclusion of important aspects such as liquefaction induced damage and refinement of the transportation network. The main objective of this research were to refine the data from a first generation of the model to more realistically represent the bridge inventory, to address the seismicity of the Pacific Northwest, conduct sensitivity analyses of soil data on the analyses results and develop a seismic network model of Oregon bridges for purposes of assessing the seismic vulnerability of roadway segments. The first generation model relied on default settings within the program to determine the economic loss due to repair and replacement of damaged bridges. The assumptions used in the analyses have been reviewed and Oregon specific data was incorporated for the model. The largest earthquake now considered to be at a highest level of probability in the Pacific Northwest is a subduction zone earthquake. The major shortcoming of REDARS2 is its inability to incorporate the subduction zone attenuation relationship into the analysis. To incorporate that capability into the model, shakemaps were developed by USGS for Cascadia subduction zone scenario events and incorporated as the demand on the refined model. Analyses of the transportation network incorporating bridge routes and post processing of the data with input from Oregon DOT bridge engineers resulted in recommendations toward bridge route priority strategies. The majority of the bridges that indicated the possibility of damage were types associated with multi-column bents, simply-supported concrete superstructures and simply-supported steel superstructures. Of the major highway routes that were considered, I-405, section of I-5 (from Multnomah to Clackamas Counties), I-84, I-205 and US-101 were the top five on the preliminary priority for seismic retrofit. These routes need to be analyzed more and advanced cost-benefit investigations should be done before retrofit decisions are made. Close

• 8. [Article] Reducing Seismic Risk to Highway Mobility: Assessment and Design Examples for Pile Foundations Affected by Lateral Spreading

  Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (e.g., Ansal et al. 1999; Seed et al. 1990; EERI 2010, EERI ...

  Citation × Citation Citation Abstract Copy Title: Reducing Seismic Risk to Highway Mobility: Assessment and Design Examples for Pile Foundations Affected by Lateral Spreading Author: Ashford, Scott A., Scott, Michael H., Rayamajhi, Deepak Year: 2013 Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (e.g., Ansal et al. 1999; Seed et al. 1990; EERI 2010, EERI 2011; GEER 2010a, GEER 2010b, GEER 2011). For example, a reconnaissance report from a recent subduction zone event, the 2010 Chile earthquake (Mw=8.8), showed the pervasive nature of liquefaction and liquefaction-induced lateral spreading damage to bridge foundations (GEER 2010a, Yen et al. 2011). In terms of seismic hazard, the Pacific Northwest shares similar conditions from a Cascadia Subduction Zone (CSZ) earthquake source with the expected earthquake magnitude of 9.0 (Mw) and return period of 300 years (Atwater et al. 1995, Atwater and Hemphill-Halley 1997). The risk and damage from a CSZ earthquake event is widely recognized by the Oregon Department of Transportation (ODOT) as presented in a report by ODOT (2009). A large number of bridges were found to be vulnerable to a CSZ event, and repair and replacement costs of Oregon bridges have been estimated at more than 1 billion USD (ODOT 2009). Moreover, thousands of bridges require some kind of modification and/or seismic retrofitting to the foundation in order to improve seismic performance under liquefaction induced lateral spreading. To evaluate the seismic performance of bridge foundations and liquefaction mitigation alternatives, ODOT/OTREC funded collaborative research between Oregon State University (OSU), University of California at Davis (UCD), University of California at San Diego (UCSD), Hayward Baker Inc., and Pacific Earthquake Engineering Research Center (PEER). The main objectives of the research were to develop design charts for different liquefaction mitigation alternatives and to develop methodologies for assessing the performance of bridge pile foundations in laterally spreading ground. The cooperative research focuses on two aspects of liquefaction and liquefaction induced lateral spreading: (1) ground improvement methods, particularly using stone columns and deep soil mixing (DSM) grids, and (2) assess the seismic performance of bridge foundations (e.g., drilled shaft, pile groups) and seismic retrofitting alternatives for the bridge foundation. Stone columns for liquefaction mitigation and pile groups foundation assessment were investigated by the OSU team, while DSM and large diameter piles/shafts alternatives were investigated by the UCD team. Research teams used OpenSees (http://opensees.berkeley.edu/), an open source computational platform for three dimensional (3D) finite element (FE) modeling and analysis. OpenSeesPL, a graphical user interface developed by the UCSD team, was used to investigate liquefaction mitigation alternatives (i.e., stone columns and DSM grids) and the performance of pile foundations in liquefaction induced laterally spreading ground. Title: Reducing Seismic Risk to Highway Mobility: Assessment and Design Examples for Pile Foundations Affected by Lateral Spreading Author: Ashford, Scott A., Scott, Michael H., Rayamajhi, Deepak Year: 2013 Damage in pile supported structures due to liquefaction and liquefaction induced deformation were reported in past earthquakes around the world (e.g., Ansal et al. 1999; Seed et al. 1990; EERI 2010, EERI 2011; GEER 2010a, GEER 2010b, GEER 2011). For example, a reconnaissance report from a recent subduction zone event, the 2010 Chile earthquake (Mw=8.8), showed the pervasive nature of liquefaction and liquefaction-induced lateral spreading damage to bridge foundations (GEER 2010a, Yen et al. 2011). In terms of seismic hazard, the Pacific Northwest shares similar conditions from a Cascadia Subduction Zone (CSZ) earthquake source with the expected earthquake magnitude of 9.0 (Mw) and return period of 300 years (Atwater et al. 1995, Atwater and Hemphill-Halley 1997). The risk and damage from a CSZ earthquake event is widely recognized by the Oregon Department of Transportation (ODOT) as presented in a report by ODOT (2009). A large number of bridges were found to be vulnerable to a CSZ event, and repair and replacement costs of Oregon bridges have been estimated at more than 1 billion USD (ODOT 2009). Moreover, thousands of bridges require some kind of modification and/or seismic retrofitting to the foundation in order to improve seismic performance under liquefaction induced lateral spreading. To evaluate the seismic performance of bridge foundations and liquefaction mitigation alternatives, ODOT/OTREC funded collaborative research between Oregon State University (OSU), University of California at Davis (UCD), University of California at San Diego (UCSD), Hayward Baker Inc., and Pacific Earthquake Engineering Research Center (PEER). The main objectives of the research were to develop design charts for different liquefaction mitigation alternatives and to develop methodologies for assessing the performance of bridge pile foundations in laterally spreading ground. The cooperative research focuses on two aspects of liquefaction and liquefaction induced lateral spreading: (1) ground improvement methods, particularly using stone columns and deep soil mixing (DSM) grids, and (2) assess the seismic performance of bridge foundations (e.g., drilled shaft, pile groups) and seismic retrofitting alternatives for the bridge foundation. Stone columns for liquefaction mitigation and pile groups foundation assessment were investigated by the OSU team, while DSM and large diameter piles/shafts alternatives were investigated by the UCD team. Research teams used OpenSees (http://opensees.berkeley.edu/), an open source computational platform for three dimensional (3D) finite element (FE) modeling and analysis. OpenSeesPL, a graphical user interface developed by the UCSD team, was used to investigate liquefaction mitigation alternatives (i.e., stone columns and DSM grids) and the performance of pile foundations in liquefaction induced laterally spreading ground. Close

• 9. [Article] Seismic Retrofit Benefit Considering Statewide Transportation Assessment

  The purpose of this study was to identify and demonstrate a methodology to prioritize bridges for retrofit in the State of Oregon. Given the limited resources available, retrofitting all vulnerable bridges ...

  Citation × Citation Citation Abstract Copy Title: Seismic Retrofit Benefit Considering Statewide Transportation Assessment Author: Mehary, Selamawit Tesfayesus, Dusicka, Peter Year: 2015 The purpose of this study was to identify and demonstrate a methodology to prioritize bridges for retrofit in the State of Oregon. Given the limited resources available, retrofitting all vulnerable bridges in the foreseeable future would not be practical. Instead, a retrofit strategy needs to be developed to prioritize the inventory and enumerate the retrofit cost. In this study, a prioritization methodology used a holistic assessment of overall roadway system to consider highway route segments, rather than individual bridges. The overall assessment was based on a cost-benefit analysis including retrofit cost, expected economic loss (with or without retrofit) and social loss caused by system wide travel time delays. A review of 2010 ODOT bridge inventory suggested that a continuous concrete girder bridge (CCGS) with three spans could be utilized to represent a sizeable portion of vulnerable inventory for Oregon highways bridges. After reviewing several potential retrofit measures, carbon fiber composite material was selected for retrofit of vulnerable columns representing those built from the 1950s to mid-1970s. Four full-scale typical square columns were tested to failure. The results showed that despite the intentionally selected square geometry of the reinforced concrete columns, the CFRP composite material showed to be an effective retrofit measure and could be deployed for to address this deficiency. The software package REDARS2 was used for seismic risk analysis (SRA) of the highway network in this study. This platform was adopted to simulate the impact of scenario earthquakes in an effort to assess the expected benefit considering direct bridge costs as well as social costs from traffic induced delays resulting from seismic retrofitting of a particular bridge type. The assessment considered three scenario Cascadia Subsection Zone earthquakes of magnitudes 9.0, 8.5 North, and, 8.5 South. The study area included all highway routes west of the I-5 corridor, highway routes in the Portland area, the entire length of US-101 and extending partially east on I-84 Columbia River Highway. Due to the considerations of a single bridge type and other limitations identified in the seismic analysis software (REDARS2), the retrofit assessment outcomes should be regarded as a first order estimate. Title: Seismic Retrofit Benefit Considering Statewide Transportation Assessment Author: Mehary, Selamawit Tesfayesus, Dusicka, Peter Year: 2015 The purpose of this study was to identify and demonstrate a methodology to prioritize bridges for retrofit in the State of Oregon. Given the limited resources available, retrofitting all vulnerable bridges in the foreseeable future would not be practical. Instead, a retrofit strategy needs to be developed to prioritize the inventory and enumerate the retrofit cost. In this study, a prioritization methodology used a holistic assessment of overall roadway system to consider highway route segments, rather than individual bridges. The overall assessment was based on a cost-benefit analysis including retrofit cost, expected economic loss (with or without retrofit) and social loss caused by system wide travel time delays. A review of 2010 ODOT bridge inventory suggested that a continuous concrete girder bridge (CCGS) with three spans could be utilized to represent a sizeable portion of vulnerable inventory for Oregon highways bridges. After reviewing several potential retrofit measures, carbon fiber composite material was selected for retrofit of vulnerable columns representing those built from the 1950s to mid-1970s. Four full-scale typical square columns were tested to failure. The results showed that despite the intentionally selected square geometry of the reinforced concrete columns, the CFRP composite material showed to be an effective retrofit measure and could be deployed for to address this deficiency. The software package REDARS2 was used for seismic risk analysis (SRA) of the highway network in this study. This platform was adopted to simulate the impact of scenario earthquakes in an effort to assess the expected benefit considering direct bridge costs as well as social costs from traffic induced delays resulting from seismic retrofitting of a particular bridge type. The assessment considered three scenario Cascadia Subsection Zone earthquakes of magnitudes 9.0, 8.5 North, and, 8.5 South. The study area included all highway routes west of the I-5 corridor, highway routes in the Portland area, the entire length of US-101 and extending partially east on I-84 Columbia River Highway. Due to the considerations of a single bridge type and other limitations identified in the seismic analysis software (REDARS2), the retrofit assessment outcomes should be regarded as a first order estimate. Close

• 10. [Article] Research Project Work Plan for Impact of Cascadia Subduction Zone Earthquake on the Seismic Evaluation Criteria of Bridges

  The goal of this project is to provide ODOT with the best rational estimate of ground acceleration values for designing new and retrofitting existing bridges. The objectives are to: evaluate the hazard ...

  Citation × Citation Citation Abstract Copy Title: Research Project Work Plan for Impact of Cascadia Subduction Zone Earthquake on the Seismic Evaluation Criteria of Bridges Author: Dusicka, Peter Year: 2013 The goal of this project is to provide ODOT with the best rational estimate of ground acceleration values for designing new and retrofitting existing bridges. The objectives are to: evaluate the hazard by contrasting the acceleration values from individual CSZ events to PSHA values provide experimental evidence of damage difference under longer duration shaking expected from CSZ event Title: Research Project Work Plan for Impact of Cascadia Subduction Zone Earthquake on the Seismic Evaluation Criteria of Bridges Author: Dusicka, Peter Year: 2013 The goal of this project is to provide ODOT with the best rational estimate of ground acceleration values for designing new and retrofitting existing bridges. The objectives are to: evaluate the hazard by contrasting the acceleration values from individual CSZ events to PSHA values provide experimental evidence of damage difference under longer duration shaking expected from CSZ event Close