Seismic Upgrading - Retrofitting of Buildings

This historic landmark in the San Francisco Bay Area was built in 1914. Since the Loma Prieta (1989) earthquake, the steel frame building with masonry infill has been completely rehabilitated. Due to the limited strength of the existing structure, the seismic isolation concept was applied. At that time, it was the tallest seismically isolated building of the world.

Special base isolators were placed under each building column. The foundation thickness above the seismic isolators was increased by adding new concrete around the perimeter of all footings. The interaction between old and new concrete was improved with Ø32 mm DYWIDAG Transverse Bar Tendons (THREADBAR^®) that passed through cored holes.