Hyatt Regency Skywalk Collapse Loading Demonstration

[@matthewstorer2379]

What I find interesting is the first model failed exactly how the Hyatt collapse failed. The 2nd story busted loose and dropped a few inches. Then seconds later, the 4th floor failed pancaking to the 2nd and so on. Pretty interesting.

[@blancaroca8786]

I think the fail point was the nut taking the double load which results in the 4 th floor going first.

[@Jman3881_]

@@blancaroca8786 technically. in the actual collapse you can see the rod and nut shear through the box beam

[@thesage1096]

@@Jman3881_ its hard to find drawings of the actual connections. i dont kno if u might be aware, but did they actually just bore and bolted tru the box beam as simply as that ? did they not even at the connection point, add stiffeners and increased the wall thickenss of the box beam ?

[@thesage1096]

box beams are usually relatively thin walled given their width and depth and rated load capacity, because they are usually not designed to carry such point loads, they usually as far as i know transfer loads by bearing ( on columns or other beams with their entire width resting on an even surface), or by axial compression (columns) in which case they are strong

[@Jman3881_]

@@thesage1096 if you look up the case or the pictures of the damage they took 2 C channels and welded them together toe to toe. Instead of welding the outside they used the inside and put the rod through it. They said fuck it and used the most unstable way possible. In the picture you can see it sheared right through

[@laurelviolet]

Thanks for the demonstration. It's neat to see the difference between the correct design and the crappy way they built it.

[@charleshartlen3914]

Omfg haha. A literal 5 minute modelling of this in a FEM analyser would show the overlapping stress concentrations. A single shear or pull out connection is 100 times easier to calculate than a double pull out with overlapping and inverted stress distributions. The complexity of stress concentrations is an important discussion for engineers. I love how the styrofoam shows an idealized cone of pull out failure--very interesting and rare to see.

[@DeathShouldTakeMeNow]

Excellent demonstration, thank you.

[@unicute8]

you learn something new everyday

[@rckbrch]

Your channel was recommend on my YT hehe For what I know tjis actually what happened like the survivors said that they first hear a loud cracking sound then after a few seconds disasters happened. 😢 Great demonstration

[@okboomer6201]

Very good demonstration.

[@Ratlins9]

Great demonstration!

[@Saw.926]

Nice demo to understand the root causes of this accident.

[@MrSpooky520]

Great demo my man.

[@machia-mw1lm]

Design change increased load on nut #2 (and) on box beam at that point . Continuos rod distributed the load . I know of a structure in NJ with continuos rod construction design and it has been in place since the 1970's . By splitting the load you force more load on the other nut . Plus you increase the shear force on the box beam between the two rods .

[@Torvald80]

In my machine design class we ran an FEA in Solidworks that showed a severe stress concentration at the lip of the bolt hole, due to the offset, which I believe was a bigger factor in the failure (Rather than just doubling the load on the lower bolt of the upper box beam).

[@machia-mw1lm]

Agree . The offset caused severe shear stress on the end of that box beam . And in an engineering discussion in 2003 we concluded that it was that shear stress which was the most significant problem . The structure in NJ also utilizes a hollow but solid sided box beam . The seamed box beam in the Hyatt design was also a contributing factor to its ultimate failure . I'll ask permission to photograph it . I think you will find it extremely interesting , the New Jersey facility design .

[@charleshartlen3914]

Torvald Thomas is correct; FEM analysers show how the overlapping stress distributions have a multiplicative effect.

[@a914freak]

You should have taken the experiment further with the first design and used large washers to simulate spreader plates @2p of the second floor.

[@justpaddingtonbear]

Thank you for making this.

[@carmelpule1]

In my opinion as an engineer, the bad design was not as suggested here, and as in many other videos, but in the fact that the horizontal two FLANGES of the C channels were loaded as a CANTILEVER, and they did not transfer the vertical load to the vertical WIDER WEB, in a vertical manner. The vertical webs with a vertical load should have been used and not a twisting or torque load, on the flanges of the C beams. If wide THICK plates bridging across the two vertical wide webs were used with the loaded nuts, rather than using a thin washer with a small diameter, this would not have failed. Note, even the original design was no good as far as engineering logic goes, as it still loaded the two FLANGES in a cantilever torque mode, which should never be, in a C channel or an H channel. I would say that the original system would also have failed, as the welding holding the C channels together did not seem to be a good weld with no porosities and anyway, the original single rod was too close to the edge of the C beam. Exchanging the rods and placing the upper rod on the inner hole could have helped! . Thick plates with side limits, working in conjunction with the loaded nuts would even eliminate the need for welding the C beams, but I still would have used welding anyway.

[@espeis12]

What a tragedy. :-( This was very helpful. Thank you.

[@jerrywilliams4505]

Nice demo, however without a solid insert at the place where the bolt and nut pass through the tubing, it tube will collapse and split.

[@windsofmarchjourneyperrytr2823]

Structurally, this looks much like "don't put the red wires to the black." Pretty 101. Really makes me mad these people that were this stupid have a license in another state!

[@mariemccormick5419]

And the Butter finally took a toll.

[@marclegarreta]

Cool!

[@rianpermanaputra7595]

2:16 IM VERY SHOCKKKKKKK

[@bamaslamma1003]

How much does each brick weigh?

[@PeterSodhi]

bamaslamma1003 about the weight of a brick...

[@GH-oi2jf]

bamaslamma1003 - One brick-unit each. I did a physics lab in high school using brick-units, then weighed a brick at the end. I did it that way because I didn’t want to wait in line while everyone else weighing their brick.

[@mariemccormick5419]

There is no Excuses in Idiocrasy.

[@charlesballiet7074]

its just such an intuitively inferior design resting all that weight on a small surface area across the weakest part of the box beam. heck pulling load parallel to a natural separation causes failure.

[@allworldsksaxon7992]

Good try but the box beams had a part in this collapse as well...

[@GH-oi2jf]

Allworldsk Saxon - That’s true. The box beams at the middle failed with only twice the load they should have born. That is an insufficient margin of safety for such a critical structure. They could have made them more resistant to this failure mode simply by welding a reinforcing plate at the stress points.

[@chuckHart70]

Great video... but the boxes would have split eventually with the original design...yes better but still and embarrassment to engineering.

[@Philippe1613]

No wonder they collapsed...they were apparently made of styrofoam!

[@machia-mw1lm]

Not funny . This was a tragedy .

[@KeffandMac]

It was 36 years ago. I guess that's still "too soon"

[@OfficialMarkieB]

Never forget

[@dougtaylor2803]

I was going to say it if no one else did. I understand that humor does not imply callous disregard or lack of empathy but apparently some people do not. I guess the old "other than that Mrs. Lincoln, how did you like the play?" joke is out of bounds too.

[@HarryBalzak]

9/11 Americans find this joke offensive.