I work in a six story building. Construction as far as I know (not very far) is a grid of metal and concrete with brick. The building was built this February (well, we occupied it then - they were stillworking on some of the other floors)
Today there was a very loud noise. It sounded and felt like somone dropped a heavy (multi-ton) weight onto the floor below me (I’m on the 4th floor)
People on the 3rd floor also reported the sound of debris dropping.
I heard third hand that the builders say it is the building “settling”. Is this a reasonable explaintion?
There is some contruction in the area (once they dumped some very large rocks for rip-rap and that was quite loud as well)
Wood-framed buildings such as houses do settle - they’re generally held together with nails that can work loose, wood can crack and a house foundation is pretty simple compared to an office building’s foundation, but for such a large steel-framed structure that presumably has a proper foundation, it should remain in one silent piece. I’d be a bit concerned that what you actually hear was a bolt or weld cracking.
If the builders tried to shrug off any loud thunks and bangs in the 33-story hotel that opened next to my office a couple of months ago as “settling” there’d be all sorts of panic. Far as I know, the hotel hasn’t had any weird noises or settling. Similarly, the seven-story building my office is in remains in the same non-settled place it was when it was built. The only time it makes any noise is during earthquakes, and even then, it’s just light creaks and shuffling noises as the ceiling tiles get jiggled.
Isn’t it plausible that there could have been a big bolted joint somewhere that was bound up by friction, and then suddenly let go? A whole section of floor dropping an eighth of an inch would make a pretty loud noise.
No. There’s be more than one bolt per joint, first of all, and second, there’s not a lot of play between the bolts and the holes they’re in. Connections that I’ve seen going together might have anywhere from four to a dozen bolts per bracket connecting columns to beams.
Finally, those bolts get torqued pretty tight with power tools, so the chances that all of the bolts were left loose enough that the joint could move is pretty slim, and would probably be grounds for an emergency visit by the building inspector.