june 17 1981 the walkway at the hyatt regency collapsed it was a tragic event that left 114
people dead over 200 injured and swamped the surrounding hospitals isn't also an iconic
engineering failure that sends shivers down the spine of any engineer that has learnt about it i'm
going to go through the events that led up to the collapse what the actual cause of the failure was
some ways it could have been picked up before it actually occurred and lessons learned that every
engineer should take to heart it's also an event that should put fear into any engineer that has
learnt about it that a detail that is so small had such a significant impact and such a major failure
the hyatt regency had this magnificent four-story atrium with a series of walkways
and at the time on july 17th a large event was being held inside this atrium with roughly about
1 600 people attending there was many people all over the area and especially up on these walkways
went around at a 705 pm a loud crap rang out through the atrium and the
two walkways both the fourth and the second floor walkways collapsed with a thundering wall
blowing smoke throughout the whole atrium soon after the event jack gilliam's phone began to ring
you see he actually works for the firm who designed the hotel he was actually the engineer
of record so essentially the engineer that was responsible for the final design of the building
and on that phone call there was a discussion about what had actually occurred that there
had been many people dead many others injured and the fact that the rescue crews were trying to get
into the area to save many of the victims that may have been trapped underneath these walkways
the key information that they were trying to find at that time was the physical weight of
the walkways so they could work out what lifting equipment they needed to bring
into the area to better lift the walkways off the victims that were underneath them
now imagine getting that phone call especially as an engineer so this is something to take to heart
would have shocked him and i'm sure he almost collapsed when he heard about it it was definitely
a phone call that no engineer ever wants to receive and so jack having realized the enormity
of the event he quickly did the numbers about the weight of the equipment sending it off to
the rescuers so they could work out what lifting equipment they needed to bring into the area to
remove these walkways he then picked up the phone calling the design engineer that was involved with
the project and a number of the key members of the firm that he worked for they then charted a plane
and flew to kansas city to see what they could do about this problem as jack was in the air flying
to kansas city to see what he could do to help out the emergency crews then brought cranes into the
area having known the weight that they needed to lift off the victims smashing through those
big doors and began this heartbreaking procedure of lifting off the walkways off the victims to
see how many people they could actually save and during this event this is when jack and his team
landed in kansas city and arrived on site around 11 pm soon upon arriving on site they realized
there was not much they could do the emergency crews actually had it under control being there
they decided what was best for them to do was to work out why this event actually occurred
having started their inspections looking up at the top of the atrium that the rods were still in
place intact the original ones that were holding up this walkway and they're relatively undamaged
however when they look down on the floor to the walkways they can see that the walkway connection
was showing signs of significant damage so much so that it had deformed and allowed the rod to
pull right through the junction having identified potentially the key issue with the design they
then went away back to their hotels and did some quick numbers and realized this design connection
was grossly under designed so the walkways spanned between the two open areas on the different floors
allowing access around the whole atrium the walkway specifically were being hung from the
roof above through a series of rods that went down supporting the floors below it so one of
the floors was only a single floor at level three however across at level four and level two was
a double floor so one above the other these were made up of series of cross beams or cross girders
made of pfcs or c-sections that were welded back to back longitudinally along the top and
the rod then passed through them bolting up from underneath this connection was originally designed
and documented by gillum's firm however their design was slightly different to what was actually
being constructed so the original design was to have a series of single rods from top to bottom
allowing the two members to be stacked on top of each other but the rod carried both the weights
despite gillum's firm documenting the original design it was common practice back in the time
that that design would then be handed off to the fabricator who would do the numbers and change it
accordingly to wherever they want to fabricate the design and as they were documenting the
design the fabricator haven steel objected to the original design concept produced by gillum's team
you see what they were looking at was how could they physically install what had actually been
produced in the drawings and they were worried about when they lifted up that first walkway at
level four as it was going up the rods not only is it significantly hard to try and lift it up
while having the rods still hanging through there'll also be significant damage to the
rods as the likelihood of the walkway rocking as it was going up so they proposed a design change
to the original documentation and this is where the major problem lies you see the original design
was having a single rod from top to bottom where they were finding that too hard so their option
was to split that rod into two pieces so one's coming down supporting the level four walkway
split it off to a second rod and going down to the level two walkway can you see what the problem is
here yet the simplest way and the best way that i've heard talked about what this actually does
was the idea of a rock climber so you've got a rock climber and a single rope from top to
bottom each of those rock climbs can hold onto that rope independently for both their weight
but now if you get to the climber below and you tie him off to the climber above not only does
that climber have to hold his weight but he also has to hold the weight of the person below him
effectively doubling the force that he needs to hold on to and this is what this design change
actually did have you picked up the significance of the change what actually has occurred here you
can see something so insignificant has caught a major increase in the load to that connection
and just by the quicker the back hand calculation yes some modifications may have been able to head
to this connection to make it work so potentially there was not a potential problem there
however through not following it up you can see that the significance of the doubling of load
on a connection can cause a significant event so something so small as a minor change to a steel
documentation especially through checking the shop drawings something significant and something you
need to be careful of as an engineer if you're getting any benefit at this presentation don't
forget to hit the like button what that does it gets it out to more engineers and gives me
confidence in the type of content to create for you now let's keep learning about what
actually caused the collapse of the height regency walkway so that what they have done is doubled
the weight on the connection at the level four junction haven steele did contact dylan's firm
there was a discussion here about the proposed change and what they proposed to do and either the
project engineer or the project manager actually did some quick numbers at the time and over the
phone verbally said that the change was acceptable however if they could submit the design change in
writing so it could be officially approved and checked this was never done now this is
potentially where one of the biggest factors and this is the human-made factor here while he did do
the numbers the original engineer and did think that it was going to be okay how come he didn't
document it somewhere that this would need to be followed up yes he did request that the fabricated
firm did send in the proposed change so that it could be checked however there was no follow-up
as the original fabricated never sent that through so through a simple procedure as an engineer you
could have it documented somewhere that there was a contact being had and a potential follow-up for
a design change that was going to come through so later when you were looking through the design
and the project you can say oh look there is a design change that has actually occurred
but we haven't had any closeout of it so through a little documentation procedure
at this stage this may have been able to pick up this major design flaw later on and also haven't
still you see they originally got the design they obviously documented it up and maybe even
intended to send it off to the engineer for final approval before is actually sent off they got way
too busy and having to run these new projects they handed off the design to a subcontractor but what
they'd done in the meantime they'd actually documented the revised design change so the
subcontractor coming in getting the documents seeing that it was actually currently documented
assumed that it had been designed and approved so finalize the documents for construction and send
it off for fabrication this is something to note as well when checking through design shop drawings
especially for steel it's not just something you should pass off flippantly as when we check shop
drawings as engineers it's really the last line of defense we need to make sure whatever is in
that design is structurally stable so when you're checking even as graduates shop drawings you need
to be careful with what you're looking at and make sure that it is structurally stable and if you see
something strange say something as either you will learn about a different mechanism that you may not
know about about how it actually frames up or you may actually pick up a floor like they did have
on the hyatt regency there's a major design flaw here and it has all to do with human behavior but
what's even more disturbing about this is the fact that neither connection was ever checked neither
the original proposed by gillum's team nor the revised and even the original connection after it
was assessed it was found to be only 60 capacity of the required design load that it needed to have
so even if it was designed and documented as per gillum's original design it'd still be
under capacity but then this proposed change made it even worse by doubling the force it was really
the fatal design flaw that causes significant collapse so something seemingly so small
as a revised change to a steel connection can have significant and critical effects to your
final design so you really need to be careful with everything you do so even the events
after this proposed change that we had from the contractor there was other circumstances that
could have actually possibly picked it up even earlier soon after the fabricator had actually
installed these connections there was actually significant movement actually observed on site in
the connections with one of the project surveyors actually noting it and putting in a request that
it be reviewed however this was never followed up what we can take from that especially when on site
you may be inspecting one thing but keep your eyes open as an engineer look all around to any section
that you may have visible to you you may actually be able to pick up something early on that can
save a lot of people later and just because you're looking at the reinforcement in one area does not
mean that you do not need to look at the steel work elsewhere and not just focusing on that one
key area that the inspection is made for there's also another time that it could have been picked
up when the walker has been clad with plasterboard the installer actually noted the defamation in the
connection and actually noting about how much it actually was not thinking much of it he just ended
up cladding up that connection essentially hiding the connection so that no one can actually see
the degradation that may have actually occurred up until the final collapse the investigation
into the collapse took many months and one of the investigators at the national bureau of standards
characterised the neglectful corporate nature around the entire hyatt construction project
with everyone wanting to walk away and pass on responsibility for the event and the final report
actually cited that the structural overload was from fatal design flaws into the walkways
had only minimal capacity to barely resist its own way the legal cases around this event would
also go on for many years and potential claims exceeding into the three billion dollar mark
and there was even criminal cases against both jack gillam and the project engineer they were
charged with gross negligence misconduct and unprofessional behavior in engineering however the
charges just fell short of criminal this was due to lack of evidence they also had their license
revoked across many states in the us and were very unlikely to practice engineering ever again
jack gillam did not retreat from the public eye however he took it upon himself to present many
times about the events that led up to the event and the tragic nature of what actually occurred
with him stating his purpose was to scare the living daylights out of any engineer and impact
they can have on the world around them it would also want to hope that engineering profession can
learn change and adapt from such events so that they can be better engineers and ensure that such
events could never possibly occur for jack gillan we really need to give him credit for this yes he
could have handled the events up to it better as you can see something so small had such a
big impact on the people around them and something that may be often overlooked by other engineers so
do you have any other insight into what actually occurred or any other events that you want me to
cover in detail please comment below and if you have got some benefit out of this content hit that
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