Earthquake Resistant Tower in San Francisco to Become Most Resilient Tall Building on West Coast
181 Fremont—which will become the third tallest structure in San Francisco and the most resilient tall building on the West Coast of the U.S.—has been awarded the REDi™ Gold Rating, a new earthquake resilience rating. The building was designed by San Francisco-based Heller Manus Architects.
“The 56-story mixed-use tower, built above five basement levels, is being constructed in compliance with a new set of holistic design and planning guidelines–the Resilience-based Earthquake Design Initiative (REDi Rating System)– that allow it to withstand the impact of a 475-year seismic event (roughly a M7.5-M8.0 earthquake on the San Adreas Fault) with minimal disruption.”
Developed by Arup with contributions from external collaborators, the REDi™ system outlines design and planning criteria within a resilience-based framework, creating a system that not only considers occupant safety but also takes into account the future of the building after an earthquake.
The design verification element of the system additionally includes a methodology to predict the downtime of an organization whose buildings have been damaged by earthquakes, allowing hospitals, academic institutions, corporations, and others to estimate their seismic risks.
In the 181 Fremont building, a REDi™ Gold Rating will be accomplished through “enhanced structural and non-structural design to limit damage, improved egress systems, contingency plans to reduce post-earthquake recovery times, and a development of a tenant’s resilience manual of recommendations to keep their space earthquake-ready,” among other measures.
Combined, these methods will help reduce the building’s expected repair costs by approximately 10 times compared to a code-designed building and in conjunction with contingency planning. This will reduce the expected functionality downtime from 18 months to less than several weeks.
“As the structural engineer, Arup developed innovative design solutions to achieve these objectives, including the incorporation of viscous dampers (similar to vehicle shock absorbers) within the steel megabraces and uplifting megacolumns to significantly reduce the potential for earthquake damage. Not only do these measures significantly reduce seismic forces and wind vibrations, they also resulted in material savings of approximately 3,000 tons of steel and allowed the removal of a tuned mass roof damper (the common technology to mitigate wind vibrations for occupant comfort) which freed up the entire penthouse floor for occupancy.
“Given 181 Fremont’s location in a seismic zone, building height and mixed-use nature, we felt strongly the expenditure of extra dollars to achieve a REDi Gold Rating resulted in a safer and higher quality product,” said Jake Albini, Senior Manager of Real Estate Development at Jay Paul Company. “181 Fremont will offer class A commercial space and the highest quality luxury condominiums on the market. REDi Gold enables us to also offer this real estate as the most resilient in San Francisco, allowing commercial tenants continuity of business and condo owners immediate re-occupancy of their homes after a large earthquake.”
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