Consider the hypothetical of a large group of people placed in a brick building.

Since the resonant frequency of many brick structures is 100-300hz, wouldn't kicking / punching the wall in unison (at a frequency in which one of the harmonics lines up with the resonant frequency) eventually cause the structure to start shaking? Wouldn't it eventually cause the walls to start collapsing after hours of this?

Pic related; that is what the bat-puter simulates would happen.

I mean, think about it. You can break a wall by swinging a hammer. It's hard to do it without one, because the head of the hammer is way harder material than the average hand or foot or whatever.

However, the problem is not the amount of kinetic energy the arm can deliver. Its transferring quickly / locally enough to actually crack the surface. So instead of trying to do it all at once, why not just store the energy in the resonant vibration of the brick structure?

>>16733582 (OP)
This is the same principle by how kungfu masters utilize their chi to mega punch. Visually you just see their palm coming into contact with the brick, but their chi flow is making a punch within a punch, 3 punches within two punches, etc. the resultant being on helluva [math]f^{'''''''''''}(\phi)[/math]

quite the power series

>>16733629
the strength is howmany overtones you can fit, the velocity of the punch is the fundemental frequency of what your hitting, which is why its alwasy dramatic when they slow punch to a critical hit

>>16733582 (OP)
Resonance doesn't create energy from nothing. The vibration from the initial kick will have a dampened oscillation pattern growing weaker with each period. So you'll be able to "amplify" the force up to an extent but the addition grows weaker with each additional kick until reaching a limit.

Tl;dr: harmonics ain't magic.

>>16733582 (OP)
I mean if could keep amplifying a kinetic wave you're imparting on a brick wall that's resonating with it, (without breaking your arm or wrist or various other things first) then absolutely you'll begin to destroy the bricks.
Earthquakes are a great example.