>

i would be nervous about using one of those on buildings in china.
Someone invented this thing for this purpose? >

Probably not; it was probably invented for some benign purpose (maybe, vibrating wet concrete mix to get out air bubbles?) but then some guy had some asshole neighbors and thought, "You wanna clog dance all night? Aight, imma bring home the cement vibrator!" >

In addition to seismic engineering and resonance testing, they are also used for vibratory processes like abrasive deburring, part sorting, sifting, settling granular material in packaging, etc.  Larger units are used on plate tampers but they're driven by external engines.   The business end is just an eccentric flywheel on a beefy shaft in beefy bearings.
Good secondary marketing idea, but >

Shake it up baby! >

I’m trying to image what would happen if someone bought a bunch of these and lined them up and turned them all on at once >

Better than in unison would be a timed wave state