Los Angeles City Hall
Seismic Rehabilitation and Renovation
Completed in 1928, Los Angeles City Hall, a joint venture of Albert C. Martin, John Parkinson, and John Austin, was the city’s tallest building for more than 30 years. The iconic building features a 452' high central tower rising from a two-story base, flanked by wings to the north and south.
By the 21st century, hundreds of earthquakes had shaken the building. While the building’s foundation, footings, granite base, and structural steel remained strong and intact, the unreinforced masonry walls had suffered over time, necessitating a seismic retrofit. The renovation included seismic strengthening, life safety and accessibility code upgrades, and preservation of historically significant building elements. The plan also included base isolation of the structure. Approximately 414 base isolators were inserted into columns and under walls of the building just below the existing basement level and just above the existing foundation system. Installation of the isolators required the construction of a new basement-level structural slab.
Additionally, reinforced concrete shear walls were added to strengthen existing masonry walls. A four-foot-wide underground moat, hidden from view, surrounds the perimeter of the building to allow for movement during seismic events. Once completed, the renovation was nearly invisible, allowing the historic building to retain its identity and splendor.
- Seismic reinforcement of the building through the use of base isolation;
- Compliance with all life/safety requirements;
- Accessibility for the physically disabled;
- Maximum energy efficiency in impacted areas;
- Efficient space utilization;
- Preservation and enhancement of historically significant aspects of the original architecture.
- 2003 Build America Award
- Associated General Contractors
- 2003 Modernization Award
- Building Magazine
- 2002 Office Building of theYear, Historical
- BOMA International
- 2002 Preservation Award
- Los Angeles Conservancy
- 2002 Award of Excellence
- Los Angeles Business Council
- 2001 Building Team of the Year Award
- AIA Los Angeles Chapter
- 2000 International Award of Excellence–Educational & Governmental, 2nd Place
- Design & Construction