An earthquake could put the leaning Millennium Tower at risk

The Post has learned that the Millennium Tower, better known as San Francisco’s Leaning Tower, is in trouble if just one earthquake hits the city.

Located at 301 Mission St., the building, which stands 545 feet tall, has only continued to lean forward and sink deeper west since 2015, despite the architects’ best efforts to stabilize the magnificent edifice .

The multi-million-dollar-per-unit tower at the corner of Fremont and Mission Streets is leaning more than 29 inches — more than a half-inch deeper slant than before.

Consulting engineer Robert Pyke, who specializes in geotechnical and earthquake engineering, blamed designers Treadwell & Rollo – a firm later acquired by Langan – for the foundation issues, which they found during the 2008 market crash. Citing paucity of time.

“There is a real possibility that after an earthquake, the building could be red tagged,” Pyke told The Post of the tower — a 58-story, 419-unit residence that was completed in 2009.

When a building is tagged red, it means that the structure has been severely damaged to the extent that it is too dangerous for habitation and code enforcement prohibits entry to the property without written authorization. .

Pike cites the Hayward Fault Zone—a geologic region located primarily along the western base of the Hills on the east side of San Francisco Bay—as capable of generating devastating earthquakes.

A view of the Millennium Tower on August 11, 2016 in San Francisco, California.  A $500 million lawsuit has been filed against the owner of the Millennium Tower, Millennium Partners and the Transbay Joint Powers Authority after it was discovered that the building had sunk 16 inches into the ground and leaned two inches to the northwest.
A view of the Millennium Tower in San Francisco on August 11, 2016.
Getty Images

“An earthquake on the Hayward Fault in the East Bay could happen any day now,” Pyke said. “And even Hayward … the earthquake could be big enough to cause some significant rocking of the equipment of buildings like the Millennium Tower in San Francisco. So I think that’s actually at least temporarily out There is a long-term risk for homeowners to let go.

Additionally, Pyke explained that the tower would never return to level.

And while a collapse is unlikely, since it would need to tilt “ten feet” for that to happen, Pyke said, if the tower is closer to 40 inches, elevators and plumbing will stop working, and residents will be outside. forced to go.

Pyke said the current fix hasn’t worked and likely won’t work because of the switch from steel to concrete in its original 2005 build—which makes it heavier and tougher.

“It didn’t turn out well because the effective increase in the weight of the building was quite significant. It was a third or more than before. And so the technical thing it did was stress the Old Bay clay layer that was under the sand layer.

The half-inch tilt was reportedly achieved while engineers dug under the sinking condominiums earlier this year to support the tower's weight — which was built atop a former landfill — on both sides of it.
The half-inch tilt was reportedly achieved while engineers excavated earlier this year to support the tower’s weight beneath the sinking condominium — which was built on top of a former landfill — on both of its sides.

Pyke said that to prevent any more fiddling, he would abandon his current fix effort, which he says has “too many uncertainties.”

Instead he would drill borings (a cutting process that involves the use of a single-point cutting tool or boring head to enlarge an existing hole in the workpiece) on the south and east sides of the tower to remove some of the soil in the old tower. Bay soil layer for leveling the building.

“carefully!” Pike said.

“It’s like what was done to the Leaning Tower of Pisa. Presumably continuing settlement will then stop or slow down so much that it doesn’t matter, but if it continues I will freeze Old Bay Clay.” I can!

Meanwhile, Ron Hamburger, the project engineer responsible for the building, told NBC in a statement that roof data is prone to weather fluctuations and that purely foundation-based data are more reliable.

“We are absolutely confident that after transferring the remaining design load to the pile,” Hamburger said, “there will be no further … westward movement of the roof.”

Source link

Leave a Comment