dont estimate that tall metal column will be fix ... it will definitely plastificate near fixed base and will behave more like pinned one.... so brace your tall steel!
@NairoukhMouhannad Resonance frequency is a function of the mass of the system, and the stiffness of the system. The formula ω² = k/m is the basic formula to determine natural frequency (or resonance). k is also a function of length: k = (AE)/L, where A is the cross section area of the spring member, E is youngs modulous of that member and L is the length. So the equation for resonance can be re-written as: ω² = (AE)/(mL). This shows that the natural frequency is inversely related to length.
@Asusisuful Each structure has it's own natural frequency. Like for example, a tuning fork has a natural frequency when you hit it. No matter how hard or where you hit the tuning fork it will vibrate at that natural frequency. When the table vibrates at the natural frequency of the structure it begins to resonate. This means the waves add and the vibration of the structure becomes bigger as shown in the video.
Tall Buildings have high fondamental vibration period (low frequency), so are more sensitive to low frequency shaking. Conversely, short buildings with low fondamental period( high frequency) are more affected with high frequency shaking...
I've seen this years ago. This guy was able to make an entire steel bridge vibrate by attatching this small device to one of the support beams. If he left it on there it would have been possible to eventually bring the entire bridge down.
@NairoukhMouhannad (Sorry, hit the character limit). So, when we increase the length, the natural frequency shrinks. Inversely, decreasing the length with increase the natural frequency. This lab is demonstrating that effect.
The flexibility of the tall one will let it stay together and not break as much, the middle one should mostly be affected because there was a study and medium sized buildings are mostly to break.
Going through the analysis and developing your response spectrum you're essentially creating an envelope based on site conditions and building frame type. From there once the period is known you get your Ss, S1...and so on. If you picture these three models as different points on that curve it's easy to see how changing your period (direct function of frequency) can move you back and forth to the design S values. It's pretty neat if you ask me.
great demonstration. I was wondering if there is a method or an app that lets you measure the horizontal vibration against the vibration of the strings.
How to survive an earthquake with a high frequency : Build taller. How to survive an earthquake with a low frequency : Build smaller. How to survive any earthquake : Live outside.
This is not a good test, he changes the speed of the push / pull arm and this exceeds the ''uprights'' ability to stay rigid. He basically, just found the limits of the metal based on the load and height of the design... Playing devil's advocate... I could argue that this is the side profile of a bridge that can ride on rails and the attached columns are ''free standing columns supported by two ''wire columns'' .... Totally, cannot think of a real World situation for this upright design... perhaps steel columns with a an unsupported span with a ''roof load''... So, NO lateral bracing ? Which building code would allow for this ? Especially, under the potential loading conditions presented? Again, he changed the speed of the arm and this reversal of direction is sudden on each end... it does a 180 degree about face! This creates a jerking motion that would probably cause shear failure long before this design would wobble as presented... I am bias on this... ( I like to disclose my bias position -- it helps to know you are bias and in that way, you can open your mind up to new data and possibly a new conclusion)... If, you want to comment or are triggered to reply to my comments... please do so, but please, do not add more data than what is presented by this video...
Actually this experiment should be tried as P and S type of waves like real earthquake.You can be right.And after watching this experiment I think why little houses which generally built 2 floors in Japan doesn't crush.
Well isn't that interesting ,,,, I was watching japanese girls playing at the beach,,, I tell you I sure learn alot about stuff I never heard about before on youtube,,, now I think I will type in 56 chevy and see where I end up next!
