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
Multifamily Housing | May 27, 2015
‘European’ living comes to The Woodlands with its first condo tower
Treviso at Waterway Square will offer a dynamic downtown setting with numerous live/work/play options.
Multifamily Housing | May 19, 2015
Zaha Hadid unveils 'interlocking lattice' design for luxury apartments in Monterrey, Mexico
Hadid's scheme was inspired by the Mexican tradition of interlocking lattice geometries.
Multifamily Housing | May 19, 2015
Study: Urban land use policies costs U.S. economy $1.6 trillion a year
The research contends that more affordable housing options can help cities generate significantly more income.
Multifamily Housing | May 17, 2015
New York City runs into affordable housing dilemma
New York City’s affordable housing policy has created attractive low-cost housing, but the price of success has been high.
Sponsored | Coatings | May 14, 2015
Prismatic coatings accent the new Altara Center
This multi-use campus will contain a university, sports facilities, medical center, and world-class shopping
High-rise Construction | May 6, 2015
Two new designs submitted for New York City Riverside Center
Both designs reference the cantilevers and other elements featured in architect Christian de Portzamparc’s original masterplan for the complex, which has now been scrapped.
High-rise Construction | May 6, 2015
Parks in the sky? Subterranean bike paths? Meet the livable city, designed in 3D
Today’s great cities must be resilient—and open—to many things, including the influx of humanity, writes Gensler co-CEO Andy Cohen.
Mixed-Use | May 5, 2015
Miami ‘innovation district’ will have 6.5 million sf of dense, walkable space
Designing a neighborhood from the ground-up, developers aim to create a dense, walkable district that fulfills what is lacking from Miami’s current auto-dependent layout.
Codes and Standards | May 1, 2015
Colorado House kills construction defects bill
The legislation would have made it harder for condo owners to sue builders.
Multifamily Housing | May 1, 2015
Trade groups extend campaign to promote apartment living
The groups claim that there are more than 37 million Americans—12% of the population—living in just under 20 million apartment units nationwide. Apartments and their residents contribute $1.3 trillion annually to the economy.
