![]() The wall – built to protect the underground parking structure next door – is buried beneath the 10-foot thick mat foundation, right under the higher side that needs to sink if the tower is going to straighten out even a few inches. If it turns out the tilt doesn’t improve more, experts say that 90-foot-high underground wall under the foundation’s east side may be to blame. “Any recovery is welcome news but is not the primary objective of the retrofit and would be expected to occur gradually over time,” DBI said in a statement. Officials with the city’s Department of Building Inspection credit the fix for having stopped the tower’s tilt troubles from getting worse. While Millennium fix officials acknowledge there has been less tilt and settlement improvement than the computer model predicted at this point, they stress that: “given the many assumptions and simplifications inherent” in such analyses, they see the “match between measured behavior and the analysis as excellent.” ![]() If the tower does not right itself any further, the high-rise could be left permanently tilting 29 inches as measured at the northwest corner of the roof. “Unless you were magically able to jack the building up further,” he said, “we are still left with a significant tilt of the building.’’ Poulos suspects tilt recovery peaked right after jacking was done. The simulation analysis predicted as much as four inches of offset in the tower’s tilt, occurring at a continuous rate during the first six months after jacking.īut the recent monitoring data shows that after the early progress of three quarters of an inch of tilt improvement over nine days, tilt improvement has stalled in the more than two months since. To predict how the building would behave following jacking – that’s the process of shifting some 18 million pounds of weight onto the new support piles – Millennium fix engineers relied on an elaborate computer model. That work-related settlement has resulted in about 10 inches of additional tilt.Millennium Tower residents complain of unpleasant byproduct of continued tilt That’s equivalent to how much the building has sunk since the so-called fix began. He says the work could result in as much as two inches of additional settlement. Pyke says he’s concerned that digging down 25 feet and removing dirt on two sides of the structure – where it currently is leaning the most – will mean the loss of earth that is currently buttressing the existing foundation. In a March 14 letter to building official Neville Pereira, Pyke wrote, “I am now warning that there are many uncertainties associated with the excavation that is necessary to construct the mat extensions.” “I think it’s very risky,” said veteran local geotechnical engineer Bob Pyke, who has repeatedly warned city officials about the viability of the fix. Millennium fix designer Ron Hamburger has indicated the building is expected to tilt a little more by the time work is done, but experts fear the new digging to make way for an expanded foundation could make the building sink and tilt more than anticipated. Sign up for NBC Bay Area’s Housing Deconstructed newsletter. Get a weekly recap of the latest San Francisco Bay Area housing news.
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