[Pedestrian]

Millennium Tower’s sinking and tilting creates 1-inch gap with 12-story podium structure
Roland Li
Feb. 23, 2022
Updated: Feb. 23, 2022 6:19 p.m.

Millennium Tower’s sinking and tilting has created a 1-inch gap between the main tower and smaller 12-story podium structure, the building’s project engineer said on Wednesday.

The 60-story tower in San Francisco’s Transbay area has sunk 18 inches and rotated slightly, resulting in the gap with the smaller building, which contains 53 condo units. The tower is tilting to the west by around two feet.

“We have fully considered this in our evaluation of the building’s structural safety and determined that the building is not at risk due to this movement, or any movement likely to occur before construction completion,” said Ron Hamburger of Simpson Gumpertz & Heger, the project engineer, in a statement.

Engineers plan to install 18 piles to relieve weight from the building’s foundation and mitigate the sinking and tiliting in a $100 million fix, down from an earlier 52-pile plan that resulted in more sinking.

NBC Bay Area first reported the gap between the two structures and described it as sliding, but the building’s management said the tower was not sliding.

Hamburger said the installation of piles could reverse some of the gap.

“Once the voluntary upgrade is complete, further settlement of the building at the northwest corner will be arrested, some rebound will occur, and slight additional settlement of the rest of the main tower will act to reverse the tilting that has occurred and close the gap between the elevator thresholds in the adjacent podium building that connects the main tower and mid-rise together,” Hamburger said.

The podium building sits on top of a five-level underground parking garage, and in 2019, state inspectors prohibited the use of an elevator connecting the garage to the tower because of a widening gap.

That gap was repaired, state inspectors signed off and the two garage elevators are back in service, said James Zaratin, Millennium Tower general manager.

“There was previously a gap between the threshold and the landing floor on the two parking garage elevators in the podium section of the building,” Zaratin said in a statement. “Mitsubishi Elevators has remedied this gap by extending the thresholds to ensure code compliance.”

City officials and building engineers concluded the building remains habitable and is safe even if a major earthquake occurs.

https://www.sfchronicle.com/sf/artic...s-16942587.php