Sports Fans' Unison Chant-Dances Dangerous?

Do you think sports fans jumping in unison could cause structural failure?

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No Joy

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No Joy
I find this behavior potentially dangerous. Naïvely innocent, the outcome possibly could be horrific.

Utah State University (USU) Basketball "I Believe That We Will Win" Chant
http://youtu.be/YH65jS-EseQ

Destructive Resonance

Soldiers are supposed to walk out of phase, rather then march in unison across structures. Marching in unison can overload many structures, and sometimes it's a natural resonance that can amplify the maximum stress. The oscillations also can prematurely fatigue structures.

I think sports fans that are moving in unison in such a fashion as in the video could possibly overload the grandstands, and/or stadium.

Why Do Soldiers Break Stride On A Bridge?
http://www.livescience.com/34608-break-stride-frequency-of-vibration.html
 
Now there's a topic I have never given a second thought. I, personally, am not too concerned about structure issues. I guess I should bring my ANR headset
 
Unless it's some parade soldiers aren't going to be marching anywhere. That's why God invented the Huey.
 
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Badger fans have been doing it between the 3rd and 4th quarters at Camp Randall Stadium since at least the mid 70s, and so far so good.
 
I was involved in a building project back in 2006. The buildng was a meeting space set up to seat 5500ish.

It filled up the first night...FULL...the kids in the audence we bouncing in beat with the music...caused quite a panic as eh balcony was visibly moving.

We were on the team that was called in to measure the deflection in the balcony...it was about 2.2" The strucural enginner wasn't worried in the slightest once it was measured several times...he notated the deflecton and went back home...

The building IS stll standing...
 
Kelvin said:
I was involved in a building project back in 2006. The buildng was a meeting space set up to seat 5500ish.

It filled up the first night...FULL...the kids in the audence we bouncing in beat with the music...caused quite a panic as eh balcony was visibly moving.

We were on the team that was called in to measure the deflection in the balcony...it was about 2.2" The strucural enginner wasn't worried in the slightest once it was measured several times...he notated the deflecton and went back home...

The building IS stll standing...
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2.2" sounds like a lot, but it depends on the variables. If a building engineer that knew the materials and design thought it was acceptable, then it should be all right.

Without knowing the materials and design, I would be spooked if a balcony dropped repeatedly 2.2 inches from kids jumping.
 
No Joy said:
Soldiers are supposed to walk out of phase, rather then march in unison across structures. Marching in unison can overload many structures,
Click to expand...

Yeah, like maybe one bridge once got taken out by this, like 300 years ago or something. Not a concern anymore.
 
No Joy said:
2.2" sounds like a lot, but it depends on the variables. If a building engineer that knew the materials and design thought it was acceptable, then it should be all right.

Without knowing the materials and design, I would be spooked if a balcony dropped repeatedly 2.2 inches from kids jumping.
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Rule number 1.....

When a licensed engineer says all is well and their work is not going to fail.... NEVER believe them....:no::no:

If the natural frequency of a structure aligns itself with a imposed one by another source then harmonics can and will bring down the structure....

Any decent engineer will tell you that..

http://www.youtube.com/watch?v=
 
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On my list of things to worry about, that one numbers roughly 10,675.
 
The sky is falling! the sky is falling!

get real
 
N801BH said:
Rule number 1.....

When a licensed engineer says all is well and their work is not going to fail.... NEVER believe them....:no::no:

If the natural frequency of a structure aligns itself with a imposed one by another source then harmonics can and will bring down the structure....

Any decent engineer will tell you that..

Click to expand...

I have a book that covers some engineering disasters and this one is in there. As I recall, it was a design change to ease fabrication/construction that lead to the issues. The flip side of that statement, however, is that the original design of the engineer was virtually unbuildable in the field.

As I recall, the original design had continuous rods for hanging the walkways. Along those rods were threaded sections to hold nuts to hold each individual walkway level. Imagine a 3 story rod with 6" long threaded sections at each level. The rod diameter smaller than the minor diameter of the threaded section.

First - how do you create the thick section to thread? Do you turn down a 3 story rod? Do you build up weld where you need threads then thread? Then, once the areas are threaded, do you slide box beam sections from the bottom - moving them up 2-3 storys to the threaded areas, following along with the nuts and washers. Just a bad design..... Maybe it would have worked with very long union nuts and one-story long sections, but those large union nuts (i'm guessing) would have ****ed off the architect's "vision"

Second - someone decided to make it more buildable by changing to each level supporting the level(s) below through the box beams..... easy to build, but not a good answer.

Not to minimize the tragedy but very interesting to examine.

I have some Canadian friends who are engineers. They wear the "iron ring". That hotel tragedy is a great source of material for those rings....
http://en.wikipedia.org/wiki/Iron_Ring
 
things like stadiums and gymnasiums and bridges and stuff are built with a lot higher margins than airplanes. natural frequency issues are well known and have been since the tacoma narrows bridge. i wouldn't worry about it.
 
N801BH said:
If the natural frequency of a structure aligns itself with a imposed one by another source then harmonics can and will bring down the structure....

Any decent engineer will tell you that..

http://www.youtube.com/watch?v=
Click to expand...

That is true, but the case you cite was entirely a change from the engineers designs that caused a failure due to static loading. Rather than attaching each walkway to the vertical supports, they tied one bridge to the supported beam on the bridge above. Unfortunately, the beam was not designed to carry this additional load and deformed under the increased weight.

Somewhere I've got a picture of the Brooklyn Bridge under construction advising workers traversing the cables to "break step" when doing so.
 
tonycondon said:
things like stadiums and gymnasiums and bridges and stuff are built with a lot higher margins than airplanes. natural frequency issues are well known and have been since the tacoma narrows bridge. i wouldn't worry about it.
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And before. Bridge resonance were certainly known back to the late 1800's.
 
flyingron said:
That is true, but the case you cite was entirely a change from the engineers designs that caused a failure due to static loading. .
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There was a change................. The engineer studied it and signed off on the change... And put his stamp on the change order... Watch the video..
 
damn engineers should just stick to driving trains
 
N801BH said:
There was a change................. The engineer studied it and signed off on the change... And put his stamp on the change order... Watch the video..
Click to expand...

Well he signed off on the change, it's unclear how carefully he studied it in retrospect.

I don't need to watch the TV treatment of the VIDEO. I'm quite familiar with that investigation. We studied it back when I was in the FD training and I refreshed my memory from primary sources after you posted it. Yes, the change was approved, and it was a mistake. The cross beams were not designed to take that load even statically. This had nothing to do with people stomping their feet or any sort of resonance. There was just too much weight on that piece.
 
flyingron said:
..... There was just too much weight on that piece.
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..


Agreed..... Total engineering failure.....:mad2:..

The walkways were designed, engineered, certified and stamped by a premier engineering firm to hold 1,280 people............ and failed when only 62 people were on them :mad2::mad2::mad2:... That is inexcusable......

114 humans smashed flat as a pancake and 186 injured... :sad::sad:..
 
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