Since completing construction, the 58-story Millennium Tower has become San Francisco’s most infamous building.
The tower is founded on piles driven through soft, compressible clay soils deposited by San Francisco Bay and extending into a dense sand layer over ancient marine deposits of clays, silts, and sands, according to engineering firm Simpson Gumpertz & Heger (SGH). The building’s weight and nearby construction projects caused consolidation and lateral displacement of the soils, which led to the tower settling more than 17 inches and tilting four inches across its footprint. Needless to say, this tilting began to worry residents and thrust the building into the national spotlight.
After a two-year permitting and approval process, a fix is finally set to move forward with SGH as the engineer-of-record. SGH evaluated whether the building required structural reinforcement to restore its integrity or seismic resistance to original levels. SGH lists the outcomes of the evaluation as:
– Developed detailed nonlinear models of the structure, its foundations, and underlying soil to simulate the effects of settlement and tilting
– Conducted detailed nonlinear analyses of the structure’s response to earthquake shaking
– Designed an underpinning retrofit for the structure, consisting of jacking approximately 20% of the building’s weight onto new foundation piles (52 piles to be exact) extended to rock along the structure’s north and west sides
The fix will prevent any future settlement and reverse the current tilting over time. The project is expected to begin this fall.
Related Stories
| May 30, 2018
Accelerate Live! talk: From micro schools to tiny houses: What’s driving the downsizing economy?
In this 15-minute talk at BD+C’s Accelerate Live! conference (May 10, 2018, Chicago), micro-buildings design expert Aeron Hodges, AIA, explores the key drivers of the micro-buildings movement, and how the trend is spreading into a wide variety of building typologies.
Codes and Standards | May 30, 2018
Silicon Valley cities considering taxes aimed at large employers
The aim is to offset the impact on housing costs and homelessness by tech companies.
Multifamily Housing | May 30, 2018
Concentrated redevelopment: Apartment complex takes mixed use to the next level
An “intergenerational” mixed-use apartment complex may be a prototype for reenergizing neglected neighborhoods in America’s largest county.
| May 24, 2018
Accelerate Live! talk: Security and the built environment: Insights from an embassy designer
In this 15-minute talk at BD+C’s Accelerate Live! conference (May 10, 2018, Chicago), embassy designer Tom Jacobs explores ways that provide the needed protection while keeping intact the representational and inspirational qualities of a design.
BD+C University Course | May 24, 2018
Building passively [AIA course]
17 tips from our experts on the best way to carry out passive house design and construction for your next multifamily project. This AIA CES course is worth 1.0 AIA LU/HSW.
Multifamily Housing | May 23, 2018
Yankee Dandies: Century-old New England mills become multifamily residences
Having long outlived their original uses, two century-old New England mills have become valuable community assets once again—as multifamily residences.
Multifamily Housing | May 16, 2018
Pampering the pups: Why dog-washing stations are a must-have in multifamily developments
Self-serve dog-washing stations are reinforcing strong bonds between multifamily residents and their beloved canines.
Mixed-Use | May 16, 2018
Los Angeles mixed-use building uses prefabricated wood frame to reduce costs
SPF:architects designed the building.
Multifamily Housing | May 14, 2018
Yardi Matrix report shows U.S. rent surge in April
Year-over-year rent growth leaders in April were Orlando, Fla., Sacramento, Calif., Las Vegas, Tampa, Fla., and Phoenix.
Multifamily Housing | May 9, 2018
6 noteworthy projects: Transit-oriented rental community, micro-unit residences, and an office tower becomes a mixed-use community
These six recently completed projects represent some of the newest trends in multifamily housing.
