/sci/ - Science & Math » Thread #14383187

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do civil engineers consider resonance?

Anonymous Sun 10 Apr 19:36:53 2022 No.14383187 View Reply Original Report

Quoted By: >>14383188 >>14383190 >>14383857 >>14386260 >>14387248

when designing a building in a third world country, do civil engineers consider a car with a very loud sound system might pass near the building and somehow shatter the concrete a little with the sound?

Anonymous

Anonymous Sun 10 Apr 2022 19:37:25 No.14383188 Report

Quoted By: >>14386287

>>14383187
when they are paid to do so, yes

Anonymous

Anonymous Sun 10 Apr 2022 19:37:45 No.14383190 Report

Quoted By: >>14384626

>>14383187
I asked this because someone that matches the description just passed near my house and I felt the ground and could hear the windows vibrating a little

Anonymous

Anonymous Sun 10 Apr 2022 23:16:50 No.14383857 Report

Quoted By: >>14383965

>>14383187
>do civil engineers consider resonance?
yes
>when designing a building in a third world country
if they are good yes, but even then mitigations for it may get removed due to budget issues or corruption
>do civil engineers consider a car with a very loud sound system might pass near the building
no, lmao. it's mainly the wind (and earthquakes if you get those) that you worry about, look up tacoma bridge

Anonymous

Anonymous Mon 11 Apr 2022 00:04:13 No.14383965 Report

Quoted By: >>14384020 >>14386292

>>14383857
>tacoma bridge
I looked it up and it seems there isn't one agreed explanation to it

still, why do I hear things shaking when a loud car passes by? I don't remember if mechanical waves were supposed to do that

Anonymous

Anonymous Mon 11 Apr 2022 00:25:03 No.14384020 Report

Quoted By:

>>14383965
sound are just air waves, so of course a sound loud enough will be able to shake things around, in the same way you can "feel" the bass in your body when you go to a concert. the problem is when the structure starts vibrating at its resonance frequency as it causes the vibrations to amplify, which in extreme cases can make something like a gust of wind able to know down a building. usually, when building structures the objective is not to make them not vibrate at all as that puts strain in the structure, rather you want to prevent them from shaking at their resonance frequency only.
if you're interested in the topic, you can look up about the taipei 101. skyscrapers tend to have dampeners to help with resonance, and this one has it in the open so people can see it.
https://www.atlasobscura.com/places/tuned-mass-damper-of-taipei-101
https://www.youtube.com/watch?v=ohKqE_mwMmo
you can also find footage of building shaking from earthquakes in japan
https://www.youtube.com/watch?v=2t2xxKMN-Ic

Anonymous

Anonymous Mon 11 Apr 2022 05:53:04 No.14384626 Report

Quoted By:

>>14383190
damn that must have been a big bitch

Anonymous

Anonymous Mon 11 Apr 2022 19:09:39 No.14386260 Report

Quoted By: >>14388943

>>14383187
how the fuck do you determine the natural resonance frequency of a structure?
You create pulses by striking it with a hammer and observe the response convolution style with some 3D sensors?

Anonymous

Anonymous Mon 11 Apr 2022 19:17:52 No.14386287 Report

Quoted By:

>>14383188
First post best post, checked and based.

Anonymous

Anonymous Mon 11 Apr 2022 19:20:58 No.14386292 Report

Quoted By: >>14386339

>>14383965
Tacoma Narrows wasn't resonance, it was because physicists treated atmospheric gas as ideal (i.e. not a fluid)

this was an unfortunate result of their theories only working on paper, which forced them to hide their work from the wind that would blow it all away. unfortunately, without exposure to it, they forgot wind existed, and it blew their theories of gaseous behavior away anyway

the cosmologists and particle physicists in particular still hold onto that flow-less modeling of gas in stars, because the engineers haven't gotten around to tearing their theories to shreds yet (not enough funding and the real world examples are too far for current projects).

Anonymous

Anonymous Mon 11 Apr 2022 19:37:17 No.14386339 Report

Quoted By: >>14386349 >>14386487

>>14386292
based
if engineers took over physics and astronomy we would find the earth is flat in 3 years

Anonymous

View Same Google iqdb SauceNAO tacoma-narrows-bridge-shaking.gif, 2MiB, 498x326

Anonymous Mon 11 Apr 2022 19:39:03 No.14386346 Report

Quoted By:

nah we just sorta roll with it and hope things work out

Anonymous

Anonymous Mon 11 Apr 2022 19:40:13 No.14386349 Report

Quoted By: >>14387172

>>14386339
?=e=3=?g
g=10

Anonymous

Anonymous Mon 11 Apr 2022 20:30:03 No.14386487 Report

Quoted By: >>14386510

>>14386339
the engineers are busy laughing at the physicists for trying to build tokamaks based on ideal gas models of stellar fusion while the NIF shatters their records with ICF by accident (physicists like to trot out the fact H-bombs work as evidence we understand how stars fuse without really acknowledging the fact they are ICF devices and stellar fusion models rely on "gravitational collapse fusion" that they try to imitate and consistently fail at in MCF devices)

and wondering why the cosmologists are so fucking terrified of electromagnetism because their precious theories fall to pieces if you don't - like they did decades ago - just assume all matter is electrically neutral at large scales and never look back.

or, case in point, Planck's photon energy equation because PLANCK BAKED A UNIT CONVERSION ERROR INTO THE DEFINITION OF A PHOTON AND IT'S STILL THERE TREATING THE SECOND IN Hz AS A FUNDAMENTAL PROPERTY OF THE UNIVERSE IN THE FOUNDATIONAL EQUATION OF QUANTUM MECHANICS - i'm sorry, what was i saying? oh, yeah, i like engineers. theorists are poopoo

Anonymous

Anonymous Mon 11 Apr 2022 20:35:22 No.14386510 Report

Quoted By:

>>14386487
>just assume all matter is electrically neutral at large scales

this always bothered me

Anonymous

Anonymous Tue 12 Apr 2022 01:13:22 No.14387172 Report

Quoted By:

>>14386349
Kek.

Anonymous

Anonymous Tue 12 Apr 2022 01:42:02 No.14387248 Report

Quoted By:

>>14383187
Yes, this is one of the first things you get taught I imagine. I learned this as a concept in high school and it properly in Materials course at university and I didn't even do civil engineering, you can bet its hammered in in civil engineering degrees given how many bridges a few decades ago broke down because they didn't consider the bridge's natural frequency.

Anonymous

Anonymous Tue 12 Apr 2022 17:08:11 No.14388943 Report

Quoted By:

>>14386260
Numerically, it's an eigenvalue problem

https://en.m.wikipedia.org/wiki/Modal_analysis_using_FEMi

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