The story of the Citigroup Center building is engineering history. Citibank wanted the property, but on the corner of the building site was a church. The church agreed to sell to Citibank, but on the condition it would have a new independent building on the same corner. To do this, the bank tower would be supported by four columns. However, the church objected to a design that would plant one of the columns into the church, so the columns were placed on the side of the building and not at the corners.
When the building was complete, Joel Weinstein, the design engineer was giving a presentation at Cooper Union about the the building. One of the students quizzed Weinstein about whether the building would stand up to hurricane winds, and Weinstein assured the student that everything was fine. Afterwards Weinstein wasn’t so sure, and he and William LeMessurier, the original structural engineer recalculated the wind load of the building.
They suddenly realized it was sufficient if the wind loads came straight on, but if the wind load came at a 45° angle, the loads on the joint would increase by over 150%. LeMessurier approached Citibank about the issue, but did not tell the city. Since hurricane season approached, they worked day and night repairing the structure. When it was revealed what took place, LeMessurier was accused of putting the city in danger and attempting to protect his reputation by not telling anyone, but Citibank was given credit for immediately handling the issue.
There’s a 400 ton tuned mass damper in the very top of the building. It sits on a thin film of oil and is connected by two very large springs that sit at right angles to each other. When the building sways, the damper actually sways the other direction dampening the swaying of the building.
That one was special because they actually asked for and got Engineering approval for the change. It wasn’t just corruption and bad practice, which is what everyone assumes when there is a structural failure.
Everyone knows that corruption and bad practice is common. I was amazed that the World Trade Centre didn’t come down at the first bombing: a lot of buildings would have had trash and fill in the centre of those “solid concrete” pillars. I thought that was a tribute to the construction quality in NYC, and a justification for the notoriously high cost of NYC construction.
But the Hyatt engineers had no excuses. They approved a change without doing structural calculations, and although the point of failure was a bad fixing, even if perfect it had a calculated breaking point less than the applied load.
I live here in Kansas City, and used to eat at the two restaurants there (The Peppercorn Duck Club and Skies, the rotating restaurant on top). Everyone at the hotel has kind of a mental block - the hotels owners resisted very strongly putting up any kind of memorial or plaque, and the hotel staff were told that they were not to talk about the fact that the disaster even happened, on pain of being disciplined.
I believe I speak for us all when I say, “That’s freakin’ awesome.” Disappointing that it was needed and far from a solution, but a cool fix.
What was the punishment in the Code of Hammurabi for a man who designed a building that didn’t fall down but cost a pile of sheqels to keep it from falling down because he didn’t plan for Pazuzu, the king of the wind demons, to blow from a different direction? Was it two oxen and a hand?
Actually, a lot if buildings have tuned mass dampers. Otherwise, the occupants on the upper floors would need barf bags.
The Taipei 101 mass damper is twice as heavy as Citicorp’s and can be seen from the observation deck. It’s five stories tall. The “ball” mass is two stories tall and hangs down from the observation deck.
If you’re lucky, you might be on the observation deck during an earth quake and get to watch it in action.
Except that article only talks about epoxy failure, not bolts.
For NASA, part of the requirement is lot testing of fasteners to prove they are what they say they are. So not only do you get the CMTR from the manufacturer, and the documentation stating it is what it is supposed to be, but then you lot test the received product to prove it is up to standard.
Storage conditions should prevent deterioration. The only deterioration I can think of that could happen would be corrosion. The hydrogen embrittlement was caused during the manufacture process, specifically during galvanization.