The Millennium Tower: A Troubled Skyscraper in San Francisco

⚠️The Millennium Tower, the tallest residential building in San Francisco, has been sinking and tilting due to its foundation.

💡The building's foundation consists of a thick concrete slab and concrete friction piles that spread the load vertically and bear on the sandy soil.

💰The tower's settlement and tilting led to a decrease in condominium prices and numerous lawsuits involving various parties.

🏢Retrofitting the building's foundation involves installing piles along two sides of the tower and lifting the foundation using hydraulic jacks.

🚧Construction of the foundation retrofit faced challenges due to disturbances to the clay layer, leading to temporary halting and reassessment of the plan.

Why is the Millennium Tower sinking and tilting?

—The tower is sinking and tilting due to settlement in its weak layer of Ice Age mud called the Old Bay Clay.

How are engineers retrofitting the tower's foundation?

—Engineers are installing piles along two sides of the tower's perimeter and using hydraulic jacks to lift the foundation, transferring some of the load to the new piles.

Has the settlement and tilting compromised the tower's safety?

—Experts have assessed the tower's safety and determined that it is still safe to occupy and can withstand strong earthquakes. However, further tilting may affect its safety.

What caused the decrease in condominium prices?

—The settlement and tilting of the tower led to a loss of confidence among buyers, resulting in a decrease in condominium prices.

Are there any other buildings facing similar issues in San Francisco?

—Several tall buildings in downtown San Francisco utilize a similar foundation system, but the Millennium Tower is experiencing more significant settlement and tilting.

00:00The Millennium Tower in San Francisco, the tallest residential building, has been sinking and tilting due to its foundation.

01:30The tower's foundation consists of a thick concrete slab and concrete friction piles that spread the load vertically and bear on the sandy soil.

06:32The tower's settlement and tilting led to a decrease in condominium prices and numerous lawsuits involving various parties.

09:41Retrofitting the building's foundation involves installing piles along two sides of the tower and lifting the foundation using hydraulic jacks.

10:52Construction of the foundation retrofit faced challenges due to disturbances to the clay layer, leading to temporary halting and reassessment of the plan.

12:41The tower's complex story highlights the challenges and complexity of engineering projects, the limitations in engineering practice, and the impact of engineering and media on perception.

12:55The retrofit progress is being closely monitored, and updates will be provided in the future.