Seismic strengthening of Pasadena City Hall, part of the National Register of Historic Places, was completed in April 2007. Because of the historic nature of the California Mediterranean designed structure, special care and planning was required to ensure that current seismic standards were met whilst preserving the notable features of the circa 1927 building.

The owners of the building recognized early on that only firms with extensive experience in seismic base isolation work would be needed to achieve these goals. Sheedy, having installed more isolators than any other company in the United States, was the clear choice for performing such work.

In order to create sufficient space for the seismic base isolators, the original basement had to be completely excavated and new foundation poured in its place. Next a floor transfer system was installed upon which 240-friction pendulum isolator bearings were installed between the basement and the foundation with corresponding column loads up to 450 tons. Cost for the rehabilitation project totaled $80 million.

Friction Pendulum Isolators are placed under load bearing structures in order to create a swinging pendulum motion. The isolators are composed of concave spherical bearings and allow a structure to gently sway during seismic events. In other words, the bearings allow the ground to shake while maintaining the structural integrity of the building or bridge above. In the case of Pasadena City Hall, isolators were installed employing a new design wherein the bearings were placed off the column grid in both a longitudinal and transverse direction. Existing column load were then displaced with post-tensioned transfer girders.

Friction pendulum isolators were the best option to preserve the structure that is comprised of reinforced concrete, stucco, cast stone, tile roofs upon which a historic six-story dome rests.