Quote:
Originally Posted by LilZebra
Point is that in a similar way,, all the hollowcore and steel and glass that's being placed atop 40 year old piles that were meant for no more than a 20 storey building (based on 1974 drawings). It can only lead to a catastrophic failure at some point if something is not done soon.
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There is a lot wrong here that I need to correct for the record.
The piles are 40 years old. That is correct. But the rest of this statement is wrong.
The original building planned for this site was shorter (IIRC the total height was closer to 25 stories) However there are two very important distinctions between what was planned and what is being built:
1) original tower was an office tower, new tower is residential.
- Office towers have a design floor loading of 50 pounds per square foot for all floors above the main floor. Residential towers have a design floor loading of 40 pounds per square foot for all floors above the main floor. Floor to floor heights of office buildings are generally ~1-foot taller than residential.
2) original tower was planned with cast-in-place concrete, new tower is pre-cast hollowcore concrete.
- an 8" cast concrete floor has a dead load of 100 pounds per square foot, and equivalent topped hollowcore floor has a dead load of closer to 75 pounds per square foot.
Put this all together and you have a
taller apartment building that weighs more or less the same as the originally designed
shorter office building.
The piles really don't care how tall the building is, they care about how heavy the building is.
300 Main is designed to maximize the capacity of the existing piles.
There was a lot of investigation that went into this prior to any work getting started. I know the people that did the structural design, and we can all rest assured they are at the very top of this industry.