The Hidden Engineering of Liquid Dampers in Skyscrapers | Hacker News Reader

The Hidden Engineering of Liquid Dampers in Skyscrapers

practical.engineering

61 pointschmaynard16 comments

Toward the end, he suggests water dampers serve a dual purpose to meet fire codes (having a reservoir of water atop your building).

Does this create additional risk when firefighting operations draw it down?

i.e. Do the dampers contribute meaningfully to short term structural integrity of the building (particularly in gusty weather), or are they mainly just for comfort and materials longevity?

Has any building architected its liquid pool damper as a bonafide swimming pool?

What are the odds that an earthquake could hit at the same time as a fire? What are the odds?

An earthquake during a fire seems unlikely, but a fire caused by an earthquake seem more likely. At least the latter would happen after the earthquake.

Yes, exactly - This is what occurred (fire from an earthquake) during the tragic 1906 San Francisco earthquake (and fire): https://en.wikipedia.org/wiki/1906_San_Francisco_earthquake

The non liquid active tuned damper in Tapei 101 is a delight. Sprayed gold like a funky futurist nugget, set amongst massive hydraulic actuators.

I'm not sure you could make a liquid tuned damper be a tourist attraction.

I wonder if it would be possible to use it as an indoor swimming pool instead? People should get out when it starts damping least they get tossed around quite a bit, of course…

But they wouldn't get tossed around, that's the whole point? (Unless they are close to the pool boundary.)

I don't recall him mentioning how the viscosity of the fluid changes it's effectiveness, but I imagine it would. For reduced maintenance costs (prevent algae growth) they probably use mineral oil, not blue water.

Surely some biocide or glycol or whatever is going to be a lot cheaper than using mineral oil? This is solidly north of a hundred thousand gallons after all, right? Especially since they're already going to have plumbed water in the building anyway, so they wouldn't need to transport drums and drums of whatever liquid is chosen if it's not water?

300-400 tons of mineral oil is not expensive on industrial scales. And biocides are not as effective as you'd hope (look up biofilms for one particularly annoying example). So mineral oil is definitely a viable option. But its lower density means that water is probably going to win anyway.

Quick search says around $1,600 USD per ton for mineral oil? Taipei 101's damper is 660 tons. No idea how that compares to a fluid damper, but if we assume similar tonnage requirements that'd work out to somewhere in the range of $1M USD in mineral oil. Granted that's, what, 0.05% of the building cost? So in that sense "not a lot", sure, but compared to the almost nothing that it'd cost for an equivalent amount of industrial water, that still affords a lot of alternative solutions. Especially since it just needs to slosh around, does it even matter if stuff grows in it? It's not like there's going to be sunlight, either, so there wouldn't be much growth regardless right?

They want something that isn't a fire hazzard. And water can be connetted to the fire control system thus serving an additional purpose.

Fill it with electro-ferric shock fluid

That's a great idea. The Action Labs guy just demonstrated how some of those fluids can vary their viscosity in response to a magnetic field, used in some vehicle active suspensions. Similar application!

Cool video. I love the practical attempts at demos. Even if they don’t always work 100% it’s so much better than talking plus some semi relevant animations

Grady loves his models.

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