Heritage Preservation: The Oregon State Capitol’s Seismic Retrofit Journey

Brief

Discover how the Oregon State Capitol’s seismic retrofit, incorporating advanced engineering and historical preservation, sets a new standard for safeguarding iconic buildings against earthquakes.

Insight

The Oregon State Capitol has undergone a transformative seismic retrofit to enhance its resilience against earthquakes, a response to its vulnerability highlighted by the 1993 Scotts Mills earthquake. This historic edifice, constructed in 1938 and expanded in 1977, represents a crucial part of Oregon’s heritage, having been rebuilt thrice due to previous devastations. Recognising the significance of preserving this landmark, the Oregon Legislature has adopted an innovative approach to its seismic strengthening.

The retrofit strategy involves the implementation of a seismically base-isolated system, employing a triple friction pendulum system designed to mitigate the effects of seismic events, particularly those emanating from the Cascadia Subduction Zone. This method was chosen over traditional retrofitting techniques to preserve the building’s historic murals and interior fabric. Additionally, the retrofit includes the addition of a new level beneath the existing structure to accommodate the evolving needs of the Capitol complex.

The project also extends to the adjacent 1977 reinforced concrete buildings, which have been strengthened using a fiber-reinforced polymer system. However, unlike the main Capitol building, these structures remain fixed-base. The comprehensive approach to the seismic retrofit of the Oregon State Capitol not only ensures the structural integrity of the buildings but also preserves the historical and architectural significance of this iconic complex.

The Oregon State Capitol’s seismic retrofit project exemplifies a holistic approach to preserving heritage while ensuring safety and functionality. By balancing the need for seismic resilience with the desire to conserve historical elements, this project serves as a model for future endeavors in heritage building preservation and seismic retrofitting.

Highlight

The retrofit strategy involves the implementation of a seismically base-isolated system, employing a triple friction pendulum system designed to mitigate the effects of seismic events, particularly those emanating from the Cascadia Subduction Zone.