Risk-Informed Design of RCC Dams under Extreme Seismic Loading

The existing Scoggins Dam and reservoir are in Washington County, Oregon, and the title is held by the U.S. Bureau of Reclamation (Reclamation). Reclamation has previously identified dam safety concerns related to the existing embankment dam. Regional project sponsors, including Clean Water Services...

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Main Author: Keith A. Ferguson
Format: Article
Language:English
Published: MDPI AG 2022-12-01
Series:Water
Subjects:
Online Access:https://www.mdpi.com/2073-4441/15/1/116
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author Keith A. Ferguson
author_facet Keith A. Ferguson
author_sort Keith A. Ferguson
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description The existing Scoggins Dam and reservoir are in Washington County, Oregon, and the title is held by the U.S. Bureau of Reclamation (Reclamation). Reclamation has previously identified dam safety concerns related to the existing embankment dam. Regional project sponsors, including Clean Water Services, have identified the need for expanded storage capacity in the reservoir to meet growing water demands and address water quality issues in the Tualatin River downstream of the dam. As part of efforts to resolve dam safety issues and increase the water storage in the reservoir, a comprehensive feasibility level design of a new 185-foot-high Roller Compacted Concrete (RCC) dam. Extraordinary seismic hazards have been identified in the region associated with the Cascadia Subduction Zone (CSZ). Further, any dam alternative carried forward for funding, final design, and construction will have to meet the Public Protection Guidelines (PPG) of Reclamation that require a formal quantitative risk analysis. A risk-informed design approach was adopted to configure the layout and cross-section properties of the dam. A multi-phase site characterization program and preliminary RCC mix design program were performed to support the design. In addition, models were developed, and an extensive suite of both (two-dimensional) 2D and (three-dimensional) 3D structural analyses were performed for seismic loadings with total durations of over 200 s, strong shaking of over 140 s, and peak ground accelerations of over 2 gravitational accelerations (g) (up to 50,000-year return period event). This paper describes the feasibility design configuration of the dam, including the seismic hazard characterization, structural analysis models, and seismic response modeling results. The expected performance of the dam relative to the risk-informed design criteria and Reclamation PPGs will be generally described.
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spelling doaj.art-b98c98ad061d436badd09b695237aca62023-11-30T23:16:51ZengMDPI AGWater2073-44412022-12-0115111610.3390/w15010116Risk-Informed Design of RCC Dams under Extreme Seismic LoadingKeith A. Ferguson0Senior Technical Advisor for Dams and Hydraulic Structures, HDR Engineering, Inc., Suite 3400, Denver, CO 80220-4824, USAThe existing Scoggins Dam and reservoir are in Washington County, Oregon, and the title is held by the U.S. Bureau of Reclamation (Reclamation). Reclamation has previously identified dam safety concerns related to the existing embankment dam. Regional project sponsors, including Clean Water Services, have identified the need for expanded storage capacity in the reservoir to meet growing water demands and address water quality issues in the Tualatin River downstream of the dam. As part of efforts to resolve dam safety issues and increase the water storage in the reservoir, a comprehensive feasibility level design of a new 185-foot-high Roller Compacted Concrete (RCC) dam. Extraordinary seismic hazards have been identified in the region associated with the Cascadia Subduction Zone (CSZ). Further, any dam alternative carried forward for funding, final design, and construction will have to meet the Public Protection Guidelines (PPG) of Reclamation that require a formal quantitative risk analysis. A risk-informed design approach was adopted to configure the layout and cross-section properties of the dam. A multi-phase site characterization program and preliminary RCC mix design program were performed to support the design. In addition, models were developed, and an extensive suite of both (two-dimensional) 2D and (three-dimensional) 3D structural analyses were performed for seismic loadings with total durations of over 200 s, strong shaking of over 140 s, and peak ground accelerations of over 2 gravitational accelerations (g) (up to 50,000-year return period event). This paper describes the feasibility design configuration of the dam, including the seismic hazard characterization, structural analysis models, and seismic response modeling results. The expected performance of the dam relative to the risk-informed design criteria and Reclamation PPGs will be generally described.https://www.mdpi.com/2073-4441/15/1/116roller compacted concrete (RCC)risk-informed designCascadia subduction zone (CSZ)non-linear structural analysis
spellingShingle Keith A. Ferguson
Risk-Informed Design of RCC Dams under Extreme Seismic Loading
Water
roller compacted concrete (RCC)
risk-informed design
Cascadia subduction zone (CSZ)
non-linear structural analysis
title Risk-Informed Design of RCC Dams under Extreme Seismic Loading
title_full Risk-Informed Design of RCC Dams under Extreme Seismic Loading
title_fullStr Risk-Informed Design of RCC Dams under Extreme Seismic Loading
title_full_unstemmed Risk-Informed Design of RCC Dams under Extreme Seismic Loading
title_short Risk-Informed Design of RCC Dams under Extreme Seismic Loading
title_sort risk informed design of rcc dams under extreme seismic loading
topic roller compacted concrete (RCC)
risk-informed design
Cascadia subduction zone (CSZ)
non-linear structural analysis
url https://www.mdpi.com/2073-4441/15/1/116
work_keys_str_mv AT keithaferguson riskinformeddesignofrccdamsunderextremeseismicloading