Risk-Informed Design of RCC Dams under Extreme Seismic Loading

The existing Scoggins Dam and reservoir are in Washington County, Oregon, the title is held by U.S. Bureau of Reclamation (Reclamation). has previously identified dam safety concerns related to embankment dam. Regional project sponsors, including Clean Water Services, have need for expanded storage capacity meet growing water demands address quality issues Tualatin River downstream As part efforts resolve increase reservoir, a comprehensive feasibility level design new 185-foot-high Roller Compacted Concrete (RCC) Extraordinary seismic hazards been region associated with Cascadia Subduction Zone (CSZ). Further, any alternative carried forward funding, final design, construction will Public Protection Guidelines (PPG) that require formal quantitative risk analysis. A risk-informed approach was adopted configure layout cross-section properties multi-phase site characterization program preliminary RCC mix were performed support design. In addition, models developed, an extensive suite both (two-dimensional) 2D (three-dimensional) 3D structural analyses loadings total durations over 200 s, strong shaking 140 peak ground accelerations 2 gravitational (g) (up 50,000-year return period event). This paper describes configuration dam, hazard characterization, analysis models, response modeling results. expected performance relative criteria PPGs be generally described.