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
Resiliency | Sep 3, 2024
Phius introduces retrofit standard for more resilient buildings
Phius recently released, REVIVE 2024, a retrofit standard for more resilient buildings. The standard focuses on resilience against grid outages by ensuring structures remain habitable for at least a week during extreme weather events.
Products and Materials | Aug 31, 2024
Top building products for August 2024
BD+C Editors break down August's top 15 building products, from waterproof wall panel systems to portable indoor pickleball surface solutions.
Adaptive Reuse | Aug 29, 2024
More than 1.2 billion sf of office space have strong potential for residential conversion
More than 1.2 billion sf of U.S. office space—14.8% of the nation’s total—have strong potential for conversion to residential use, according to real estate software and services firm Yardi. Yardi’s new Conversion Feasibility Index scores office buildings on their suitability for multifamily conversion.
Adaptive Reuse | Aug 28, 2024
Cities in Washington State will offer tax breaks for office-to-residential conversions
A law passed earlier this year by the Washington State Legislature allows developers to defer sales and use taxes if they convert existing structures, including office buildings, into affordable housing.
Affordable Housing | Aug 27, 2024
Not gaining community support is key barrier to more affordable housing projects
In a recent survey, builders and planners cited difficulty in generating community support as a key challenge to getting more affordable housing projects built. The survey by coUrbanize found that 94% of respondents tried to gain community input and support through public meetings, but many were frustrated by low attendance. Few respondents thought the process was productive.
Adaptive Reuse | Aug 22, 2024
6 key fire and life safety considerations for office-to-residential conversions
Office-to-residential conversions may be fraught with fire and life safety challenges, from egress requirements to fire protection system gaps. Here are six important considerations to consider.
Multifamily Housing | Aug 21, 2024
Nation's leading multifamily developer expands into infrastructure
Greystar's strategy for infrastructure is driven by the shifting landscape of today's cities—primarily in the increased digitization, urbanization, and transitions to clean energy.
MFPRO+ New Projects | Aug 20, 2024
Seattle workforce housing project inspired by geology of eastern Washington
J.G. Whittier Apartments, a workforce housing project in Seattle uses the geology of eastern Washington as inspiration for the design. The architecture and interior design celebrate geometric anomalies found in nature. At the corners of the building, blackened wood siding “erodes” to expose vibrant murals underneath.
MFPRO+ New Projects | Aug 16, 2024
At 60 stories, the Paramount multifamily development will stand as Nashville’s tallest high rise
When complete, the 60-story Paramount building, at 750 feet high, will be the tallest high rise tower in Nashville, Tenn., surpassing the city’s current record holder, the 617-foot AT&T Building. The $390 million Paramount project recently launched condo sales after securing more than $230 million in construction financing.
Curtain Wall | Aug 15, 2024
7 steps to investigating curtain wall leaks
It is common for significant curtain wall leakage to involve multiple variables. Therefore, a comprehensive multi-faceted investigation is required to determine the origin of leakage, according to building enclosure consultants Richard Aeck and John A. Rudisill with Rimkus.
