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
Sponsored | Multifamily Housing | Aug 25, 2015
Engineered wood helps meet booming demand for multifamily projects
Multifamily housing starts reached 358,000 in 2014, a 16 percent increase over 2013 and the highest total since 2007
Sponsored | Fire-Rated Products | Aug 24, 2015
Of Sky Garages and Dezervators: Porsche Design Tower sets a new standard of cool with the help of fire rated glass
The 60-story, 132-residence luxury Porsche Design Tower designed by Sieger Suarez Architects promises to deliver a new standard of cool.
Multifamily Housing | Aug 10, 2015
SOM, Woods Bagot part of mega multifamily development planned for San Francisco's west side
The first 1,000 residential units will kickoff a decade-long plan to add 5,6779 new housing units.
Giants 400 | Aug 7, 2015
MULTIFAMILY AEC GIANTS: Slowdown prompts developers to ask: Will the luxury rentals boom hold?
For the last three years, rental apartments have occupied the hot corner in residential construction, as younger people gravitated toward renting to be closer to urban centers and jobs. But at around 360,000 annual starts, multifamily might be peaking, according to BD+C's 2015 Giants 300 report.
High-rise Construction | Aug 7, 2015
Tribute tower to cricket world champs will be Sri Lanka’s tallest
The 1996 Iconic Tower will be a tribute to the country’s cricket team, which won the World Cup in 1996.
Multifamily Housing | Aug 5, 2015
FacadeRetrofit.org: A new database for tracking commercial and multifamily façade upgrades
The site allows users to submit information about new projects, or supplement information on those already posted.
High-rise Construction | Jul 29, 2015
Jerusalem to get a high-rise pyramid by Daniel Libeskind
Are pyramids making a comeback? The city of Paris recently approved a triangle-shaped building that stirred controversy from residents. Now, the city of Jerusalem gave Libeskind's pyramid tower the go-ahead.
Contractors | Jul 29, 2015
Consensus Construction Forecast: Double-digit growth expected for commercial sector in 2015, 2016
Despite the adverse weather conditions that curtailed design and construction activity in the first quarter of the year, the overall construction market has performed extremely well to date, according to AIA's latest Consensus Construction Forecast.
High-rise Construction | Jul 28, 2015
Work begins on KPF's 'flared silhouette' tower in Manhattan
The 62-story, 157-unit luxury condo tower widens at the 40th floor, resulting in a gently flared silhouette, accented by a sculpted crown.
Multifamily Housing | Jul 27, 2015
Miami developers are designing luxury housing to cater to out-of-town buyers and renters
The Miami Herald reports on several new multifamily projects, including the Paramount Miami Worldcenter, whose homes include maid’s rooms, larger terraces, boutique-size closets, and guest suites.
