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June 13, 2023 | 5:50 p.m
The Millennium Tower, cheekily dubbed the Leaning Tower of San Francisco, finds itself in trouble when even a single earthquake shakes the city, The Post has learned.
Located at 301 Mission St., the 545-foot-tall building has steadily tilted and sunk further west since 2015, though the architects have tried their best to stabilize the swanky building.
The multimillion-dollar-per-unit tower slopes more than 29 inches at the corner of Fremont Street and Mission Street — a slope more than half an inch lower than previously announced.
Consulting engineer Robert Pyke, who specializes in geotechnical and seismic engineering, blamed designer Treadwell & Rollo – a company later acquired by Langan – for the foundation problems, citing a time crunch they found themselves in during the 2008 market crash were.
“There is a real possibility that the building will be red marked after an earthquake,” Pyke told The Post of the tower — a 58-story, 419-unit apartment building that was completed in 2009.
When a building is marked red, it means that the structure has been marked as so badly damaged that it is too dangerous to inhabit and entry to the property is prohibited without written permission from the regulatory authority.
Pyke cites the Hayward Fault Zone — a geologic zone located primarily at the western foot of the hills on the east side of San Francisco Bay — as capable of triggering destructive earthquakes.
A view of the Millennium Tower on August 11, 2016 in San Francisco.Getty Images
“A quake on the Hayward Fault in the East Bay could happen any day,” Pyke said. “And even this Hayward earthquake could be strong enough to significantly shake buildings in San Francisco, like the Millennium Tower. So I think there’s a longer-term risk that homeowners will actually have to move out, at least temporarily.”
In addition, Pyke stated that the tower would never get back to the same height.
And while collapse is unlikely, since it would require a “tens of feet” of incline, Pyke said if the tower got any closer to 40 inches, the elevators and plumbing would stop working, and neither would the occupants forced to move out.
The current solution hasn’t worked and probably won’t work because its original 2005 build switched from steel to concrete — making the change harder and harder, Pyke said.
“It turned out to be wrong because the effective increase in building weight was quite significant. It was a third or more higher than before. And so, technically, there was an overuse of the Old Bay Clay layer that was underneath the sand layer.”
The tilt was reportedly achieved by half an inch when engineers dug under the sinking condominium earlier this year to support the weight of the tower – which was built on a former landfill site – on either side.Bloomberg
Pyke said to prevent another tipping he would abandon the current attempt at repair, which he says “introduces too many uncertainties”.
Instead, he drilled bores (a cutting process that uses an indenting tool or drill head to enlarge an existing hole in a workpiece) on the south and east sides of the tower to remove some of the soil in the Old Bay Clay layer to level the building.
“Carefully!” said Pike.
“It’s similar to what was done on the Leaning Tower of Pisa. Probably then the progression of colonization would stop or slow down enough that it doesn’t matter, but if it does continue I might consider freezing the Old Bay Clay!”
Meanwhile, project engineer in charge of the building, Ron Hamburger, told NBC in a statement that roof data is vulnerable to weather variations and said foundation-only data is more reliable.
“We are absolutely confident that once the remaining design load has been transferred to the piles, there will be no further westward movement of the roof,” Hamburger said.
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https://nypost.com/2023/06/13/one-earthquake-can-put-the-leaning-millennium-tower-in-danger/?utm_source=url_sitebuttons&utm_medium=site%20buttons&utm_campaign=site%20buttons
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