Oregon Supreme Court, Modernization and Seismic Retrofit

Forell | Elsesser provided structural engineering to improve the seismic functionality, performance, and safety of Oregon’s 1914 Supreme Court Building. The 55,800 sf, three-story, Classical Revival-style building features abundant classical detailing, a grand staircase, and a historically significant stained-glass skylight in the courtroom. The modernization provides a safer, more accessible work environment for the essential workers and staff integral to Oregon’s highest courts. The project includes energy efficiency updates to interior systems and a foundation replacement with a base isolation system for seismic resilience, all while sensitively preserving the historical character-defining features of this Oregon landmark.

Seismic base isolation was implemented to significantly reduce superstructure seismic demands, which greatly reduced the hazards posed by these brittle materials. In close collaboration with the architect, owner, and general contractor, we developed a unique construction implementation strategy that allowed the structure to remain on the existing footings while the new transfer and isolation system was constructed above and around the existing foundation. After the new foundation was complete, the new foundation was preloaded by temporary shoring, allowing a single, seamless load transfer with negligible movement and no cracking in the historic finishes. This approach proved to be extremely beneficial to both construction cost and schedule.
The goal of this project is to extend the life span of this building by enhancing its seismic performance, mechanical system, and accessibility while maintaining its historic features. Our retrofit design used base isolation and ASCE 41 nonlinear analysis to limit deformation in the superstructure, thereby minimizing potential damage and alterations to the existing structure, so that its architectural characteristics are preserved and protected against future earthquakes.

Sustainable Design Strategies

Embodied carbon reducing design strategies have always been a core design principle at Forell Elsesser. We work with our clients early in design to make strategic decisions to reduce the impact a building’s structural system has on the environment. Over the years, we have consistently tracked the environmental impact of our designs using Life Cycle Assessments. We have completed LCAs on a wide range of projects – from office and residential spaces to multi storied life science and academic buildings.

Soil improvement can play a huge role in reducing embodied carbon in structures. Investing in soil improvement will have a positive impact on the site class, which in turn can reduce the seismic design category and seismic demands. Seismic design category can be a better indicator than site class alone because it accounts for risk category, which may increase the seismic demands. Across our projects, a lower seismic design category trends towards a lower embodied carbon. Where possible, the strategy of improving site class (and with it, reducing seismic design category) can achieve a 20-60% carbon reduction.

F|E recently suggested this soil improvement strategy for a new life science building in Northern California. Our team recommended and proceeded with revising from a Site Class F to a Site Class C. The shift in site class reduced the seismic demands by 60% which helped achieve aggressive sustainability goals from the owner.

Oregon Supreme Court Wins!

From Fragile to Resilient: Implementing Seismic Isolation for the Historic Oregon Supreme Court Structure.

Forell Elsesser is thrilled to announce that the Oregon Supreme Court won an Excellence in Design award, the top prize in Seismic Retrofit Category for this year’s 2023 SEAONC Structural Engineering Excellence (SEE) Awards Program. The Oregon Supreme Court Building, which utilized base isolation, was successfully re-opened in 2022 and is now one of Oregon’s most seismically resilient historic buildings!

The Oregon Supreme Court building utilized base isolation and is now one of Oregon’s most resilient historic building.

Constructed in 1914, the Supreme Court Building of Oregon is one of the state’s oldest continuously operating government buildings. To preserve the historic structure and its unique features, the Oregon Judicial Department embarked on a $55M retrofit project to protect the structure for the future. The retrofit design, which utilized seismic isolation instead of conventional fixed-base seismic strengthening, proved to be the most effective solution for simultaneously improving seismic resilience and minimizing the impact of the structural strengthening on the historic fabric of the building.