The historic Pioneer Courthouse is located in the heart of downtown Portland. Since the site covers an entire city block, access, public safety and traffic flow were critical issues. Two sides of the project block have light rail trains running every few minutes and the other sides are bus-only public transit streets with bus stops on the adjoining sidewalks.
Pioneer Courthouse was originally built in 1875, long before seismic building codes. To update the building and make it seismically sound, JE Dunn installed a friction pendulum base isolation system; at the time of construction, it was the first in Oregon and one of only fifty in the entire country.
The friction pendulum base isolation system works by separating the building from the earth, in essence creating a dry moat around the building, detaching the it from the ground at the perimeter. The isolation system allows the building to move freely from the earth up to 18 inches in each direction. All installation work happened underneath the building, preserving the historic fabric of the building.
The courthouse is now able to withstand a subduction earthquake up to 8.5 magnitude, and the interior has been carefully refurbished to replicate its original characteristics.