From my 22 year old, soon to graduate, son in college:
How do they get those big cranes up and down when they are building a building? If they have a crane big enough to lift them up and down, why don’t they just use that crane for the construction job.
I can see they might lift the crane up a floor at a time as they are working their way up the building, but how do they get it down when they’re done?
They build them from manageable pieces, bottom up. I assume they take them down in pieces too.
Back in 1989, a new high-rise BEQ (Bachelor Enlisted Quarters) went up on SUBASE Pearl Harbor, and I got to watch. Over a priod of several months, in fact. Yes, one of those super-duper cranes was in use, and I had the same question.
Alas, the SDMB did not exist in 1989, and my only way to ask Unca Cecil from Pearl Harbor would have been to write to him at the Chicago Reader, and hope that my question would appear in his next book. So I kind of blew it off.
I did notice, however, that the vertical supports for the crane were actually incorporated into the elevator shaft of the completed structure, an observation that somehow resonated with the Mike Mulligan fan in me.
Unfortunately, the construction company (that’s right, it wasn’t built by the SeaBees) did not see fit to announce when they were going to remove the horizontal component of the crane, and they managed to sneak it out without my being able to witness the hows of it all. I always suspectd that they dismantled the sucker, same as you’d dismantle a Ferris Wheel at the closing of the county fair (if you were a carny), and brought them down on the elevator.
Construction professionals are hereby invited to tear the above to shreds.
Be gentle.
I’ve seen huge mobiles being used to assemble them.
They lift each part in place and when the crane is up they go.
The boom was lifted in place by the tower crane itself - the ultimate bootstrap.
Because the mobile is lifting only parts of the tower crane one assumes that they do not need as great a lifting capacity as one might suppose.
I guess that they don’t have the capacity of the static tower cranes and because they don’t have the long boom arm they would not be able to reach down into certain areas under construction.