Classic Case Study: Hartford Civic Center

http://www.youtube.com/watch?v=4ax6eUnpa68

Just goes to show, that an engineer's job isn't done when the specs are written. Get out in the field and take a look at your work!!!!

I used to go see the Whalers hockey team occasionally back then.....................mostly Grateful Dead shows though. Good thing one of those wasn't going on. Separating the squashed hippies from the sea of tie dye would have been problematic....................but ironic.

Ahhh, to hear to noise of Brass Bonanza again!

I love to share these types of stories with others. Civil engineering is very interesting to me, especially since the area I live in has some crazy ideas in its civil engineering. Such as shutting down perfectly good crossroads and putting in a bridge, that after just 4 years now is having the same kind of problem the roof of this civic center did, i.e. someone didn't think about all the load bearing that trucks would have because they'd closed off the main crossroads of the alternative ground route. Now the city engineers admit the bridge is sinking. Scary when one thinks of all the people who pretty much have to cross it now.

Cutting corners is good in theory as it saves money, but doing it right saves lives.

How can we get out tax dollars working in our area to make the city engineers reassess the bridge and other civic building/works? No one wants to see the tragedies like the Hartford Civic Center or the I-35 bridge in Minnesota. Since the city engineers have admitted this issue but allow the bridge to continue to be used, would it be negligence on their part if the bridge ultimately fails causing injury, property damage and/or death?

Just thinking out loud here, but isn't it the civil duty of city (civil) engineers to ensure the safety of the general public by creating sound works such as bridges and structures rather than causing harm by closing safer alternative routes so that people are routed to the more precarious path of a known unstable bridge?

Wish they'd just open the alternative route again. Sure you'd have to wait at the train crossing sometimes, but at least you knew the ground wouldn't fall out from under you.

Civil engineers are also human beings and they can fail to estimate future live loads on structure.now they already accepted and find out that the bridge is sinking. Now it is peoples duty to support them to rectify the problem as early as possible. In my opinion after the problem is already analised and mistakes are accepted people should come out to support the engineers. Only those people can make mistakes who dares to do. It is easy to critisize but hard to make thing happen.

All done in an atmosphere of "accountability/responsibility/finger pointing/cover your @$$" that is all too prevalent in military, industry, neighborhood associations and the courts.

Thanks for posting this story. Each generation of Civil Engineering students, as well as design professionals currently practicing, should all be reminded of this disaster.

All too many times new engineers rely too much on computers for design purposes, without intuited insight into the program output.....what feels right and what does not feel right. I've always felt that "garbage in = garbage out".

If I cannot duplicate the analysis and design by longhand calculation, then I suspect the program output. Just call it me being very anal, but this approach hasn't failed me yet, as I've found over the years that a good many design software programs are full of bugs and insidious errors. Lest we not forget who writes the program codes, and most of the time it is IT peeps, not a licensed Professional Engineer. What may look "right" to the IT guy would most likely not be found acceptable to the PE looking over that guy's shoulder!

Another structural disaster we shouldn't forget is the Kansas City Hyatt Regency skywalk collapse back in 1981, where roughly 110+ people died. Bad design in regard to the suspension hangers and how they were attached to the walkway floor girders + no inclusion of dynamic vibration design whatsoever......people on those skyways were dancing it up mightily before it collapsed.

Yeah, the Hyatt was a bad one.

What amazes me about the civic center collapse, is that it sounds like the pieces were made properly, but the people doing the construction didn't understand how to put them together, so they just forced them into where they thought they should be.

How does that happen day in and day out, on a structure that big???!!!!

Talk about asleep at the wheel.

First, the design engineers design the compression struts incorrectly because they relied on the damn computer program that didn't take into account compression buckling....basically, these struts were acting like columns. Most were extremely overloaded (as depicted).

Usually, when design engineers start designing a structure that is "Innovative" and outside the norm, they're venturing into the unknown, as was this case. Thank God for continual tweaking/upgrading with FEM programs that practicing engineers have time-tested over the years....they're not perfect, but are much better that those we had even 15 years ago.

I do think that they designed the connections incorrectly as well, which in turn made it difficult for the parts to be adequately fabricated...then the Contractor's failure to notify the engineer of record of their observations during the field erection process.

Lots of inadequate communication between the office engineers, field engineers, the fabricator and the GC lead to this disaster. Unfortunately, it happens every day around the world. Sad.

It's not the first time a construction manager overruled an awkward design without consulting the engineers. Often enough, these guys think engineers are office pogues who know nothing about "building in the real world". Sometimes we do, and some of us don't....but that doesn't mean we didn't perform with due diligence and produce a design that works according to what's needed and wanted.

But it doesn't help when the design is awkward, expensive and the drawings are confusing. Often enough a design task is assigned to a less experienced engineer who does his best but the design isn't as good as it might (or should) be. By the time it gets reviewed, the project is far enough down the road that it is a major issue to go back and change it, so it doesn't get done.

I was once part of a project team that did the design to renovate an unused building and make it suitable for producing pharmaceutical-grade excipients. Although we were a full-service company (due to massive layoffs I no longer work there) the client declined to use us for construction management and used their own people. When the contractor put in the piping, they didn't follow the drawings or the specifications or When things didn't go together or work properly as cobbled up, or consult us when they didn't, it somehow became out fault. Because it was my process piping design, I became part of the team that had to respond to the client but no matter what we showed them or said, the client was dissatisfied and we lost any future business from them. Classic management failure trying to save money and them place blame anywhere except where it belonged.

John Maxwell says, "experience without reflection is opportunity for learning lost".

That's a great statement and someone else's experience, positive or negative, as in this case. The people who learn the greatest lessons are the one's who learn from the past experience of others. We are able to look at their thinking, right or wrong, and see the true results of that thinking. We then make application of that information in our next decisions. That is what wisdom is, the proper application of information to a certain set of circumstances.

The the worst thing that can happen is that we or someone else pays the price for a failed event and nothing is learned from it, by us or someone else. Too often we just want to forget about the failed event and put it behind us. That is basic human nature, but an inclination that needs to be overcome if we are to succeed in life.

Mistakes aren't necessarily bad, it just means we are pushing forward. Just make sure we aren't repeating the same mistakes over and over.

And now the rest of the story.

Part the first:

I was a bartender at the Cloister Lounge of the Sheraton Hotel that was connected to the Civic Center by a crossover walkway and had worked that night. When I got off work at about 2:30 AM, city snow removal crews were out in full force. In fact, a snow plow caught the rear fender of my VW Bug when he went through a red light while plowing. The snow fall during the day was very heavy, both in amount and weight. The temperature was just right that when combined with the heat generated by the building during the basketball game earlier in the evening to cause a lot of meltage which created slush on the roof. This clogged the roof drains and concentrated the weight at drain points like many large swimming pools. Being that the event was over, the heat in the arena was turned down and the drains froze, trapping water, now frozen in the four hours after the event, and heavy wet snow on the roof. The excessive load triggered the collapse.

Part the second:

The design of the roof structure was found to be proper and within accepted loading criteria. The construction on the project was done by union workers. (easy, I'm not getting down on unions) The local unions were populated and "guided" by local "fellows". This is not an assumption since I personally knew some of those "fellows" including the top "fellow", my best tipper. As work progressed, many inspection sign-offs were rubber stamped. This was verified in the investigation. In the failure analysis, the "what happened first" was found to be a strut in the roof that was in compression and supposed to be an expensive single piece form was, in an effort to reduce construction costs and line the pockets of…, substituted by four angle iron pieces welded together to produce an X cross section a few feet long. Many of these were done throughout the roof. When the load exceeded its strength, it collapsed like a Chinese lantern.

Epilog:

A security guard, in conducting his rounds, had just crossed center court and exited the arena. He slammed the door shut to be sure it locked behind him and an extremely loud crash scared the $#!^ out of him. No one was injured in the accident.

Can you imagine what that poor soul thought as he slammed the door behind him? "Jesus, I just brought down the house!"

Glad he, and others, were not hurt!!!!!

LOL!!! Good one!! Yes, it's always nice when engineers are able to learn a practical lesson without human injury.

When I think on it, maybe the vibration of the slamming door in the cavernous arena was the trigger.

I just came across an article that I think applies to the learning part of "mistakes" made in life. It's a little long but it's great for perspective in failed events.

All good points, but I think it's important to point out, that engineers don't have the luxury of repeated failures.

Whether it's designing a spacecraft, airplane, submarine, high rise building...............or many other things, if the result of a failure could be the loss of many lives, they need to check and recheck as many times as necessary to make sure, (as best as humanly possible), that failure is off the table. There were some extenuating circumstances in the roof collapse, but the bottom line is, it was preventable and shouldn't have happened.

I don't think a lot of people realize the stress that engineers work under..............................often without the pay that should go with it.

kramarat, you're very much correct in your statement that failure is not an option. Morton Thikol's failures with (I think it was gaskets) the Challenger Space Shuttle let us know there is no wiggle room for possible failure.

The point I was seeking to make with the article was that inspection of results and introspection of what we accept to be the facts needs to be done. It is the thinking process that I was addressing, not that failure is ok. All due diligence needs to be done to avoid catastrophic failures, but when they do happen, there is much to learn if we avail ourselves to the data.

We can't simply accept what has been taught, we have to be willing to look at the results of that thinking.

We as a general public enjoy a very safe life because there are engineers who do a great job and try to plan for possible contingencies that may come up and make their plan/product accordingly.

Understood. I was just pointing out that "failure" covers some pretty broad territory.

Your post was not incorrect, nor was I criticizing it. Just saying that an engineering failure on the scale of the roof collapse is in an entirely different ballpark arena, than say, failing at selling cupcakes for a living.

You're completely correct, that all failures should be learned from...........some must be learned from.

Morton Thikol's failures with (I think it was gaskets) the Challenger Space Shuttle

Not really Morton Thikol's engineering failure. The temperature envelope for the o rings was well known. And a backup o ring was in the design. When the temperature that day dipped below the threshold and an engineer pointed that out emphatically, management ignored him and made the decision to go anyway to avoid any delays in the Shuttle project schedule. Politics and money brought it down. The fix, a third o ring and adherence to the temperature envelope criteria along with sensors in the space between the o rings to monitor abnormal pressure change, although those only assist in after the fact investigation.

Pretty much every screw up can be traced back to management. Since sh*t will always roll downhill, it's the engineers that get the blame.

There you go!

It's easy to criticize the engineers for not showing more due diligence but who among us has not had the experience of being overruled by a manager whose concern for cost or some other consideration caused him to tell the engineers "just build the damned thing"? Part of the Professional Engineering Code of Ethics is not to criticize another engineer's work until you know the exact constraints the other engineer had to work under.

This is not to excuse sloppy work, because it happens too. Before the programs used in Hartford were trusted to do design whose potential faliure could cost lives, they should have been more thoroughly tested and verified by the engineers whose work depended on them. But once again, who knows if some IT manager bought the program(s) and simply told the design engineers to go ahead, the results will be fine. And was backed up by senior management, some of whose greatest talents are sidestepping responsibility for failure. Sometimes I think CYA is a required course for MBAs.

I had this experience in 1991 when the owner of the company, who loved programming, wrote a number of automated design programs and used only a single case to test them. When we actually used them, we had some very odd-looking results that I questioned but was told the "program is correct". When the owner actaully saw the real world results, he accused me of altering his program! My response was "I don't know enough about programming in Basic or how you wrote it to make any changes". It didn't endear me to him. Fortunately for me, the company had a big downsizing six month later and I was "seeking employment elsewhere". The company closed six months after that.

There is a classic joke about a man who takes a ride in a balloon but becomes lost and decides he needs directions. He sees a man on the ground and lowers the balloon so he can ask the man for them.

"Excuse me", he called out to the man on the ground "but I need some help to get to the balloon festival. Can you tell me where I am and where the festival is?"

"You're about 25 feet off the grond in the middle of the field behind my house. The feswtival is in the next county"

"Swell!" said the ballonist. "That's no help to me. You must be an engineer."

"Yes I am. How did you know?"

"Well, what you told me is techncially correct and precise but doesn't solve my problem."

"I see" said the man on the ground. "You must be in management".

That's right" said the ballonist. "How did you know?"

"Well, you don't know where you are, where you're going or how to get there. You want my help but don't like it. And now somehow it's become all my fault".

That one never gets old.

I'm not an engineer, but I've spent years as a field superintendent on some pretty massive construction jobs. I can understand why the civic center roof went together even though the pieces weren't fitting properly.

A very small part of it, is that the guys in the field don't want to look stupid. A much larger part of it, is that the architects and designers of a structure, are simply unavailable for questions.

I've been there. Find an inconsistency in a set of specs or blueprints, submit an RFI.........................and wait...............and wait. In the meantime, my schedule starts slipping, pressure builds.............At some point, you can't afford to wait. Just do it. No choice. Happens all the time.

My Dad was an engineer, and not making tons of money. I don't know if he drew the short straw, or if he was picked by management, but he had to fly over to the Lockerbie crash site to try to help figure out what happened, and if any of his company's components played a role. The dude was a mess. I like engineering stuff, but I decided at a pretty young age that it wasn't a career choice for me..............................the BS wasn't worth it.

The collapse occurred Jan 1978. Prior to 1975, I worked at Pratt & Whitney Aircraft in Experimental Engineering. At that time there were no desktop PC's anywhere in the plant. There was a single engineering calculator connected to the mainframe, in an office (fuel controls and instrumentation (X Test)) of 150 or so engineers. If you wanted to use their mainframe, you had to go to a room in the engineering building and generate decks of punch cards, submit them and wait till the next day if you were lucky. If you wanted immediate results, it took approvals from WAAAY up. If you wanted to create a program, it was done on a jumper board. Their computer was considered one of the best in the country. The U.S. Government (NASA) bought (well, traded favorable consideration when competing for contracts) time on it. When I started working at the hotel, it was 1975 and the Civic Center was 90% complete and functional for arena events. I suspect the roof was first designed at least partially, if not completely, on a slide rule. I'm not dissing slide rules, just saying I doubt computer programs played a large role although with United Aircraft (PWA, Sikorsky Aircraft, Hamilton Standard, Otis Elevator, etc.) having a strong presence in Hartford, just a couple of blocks from the center, who knows.

Interesting.....I worked at Pratt in the late 80's and even by then we design engineers did not have ready access to computers for analysis. All calculations were performed by a separate group, although we did get some rudimentary PCs for word processing (I was writing repair procedures).

Surprisingly, although my group manager was one of the worst engineers I've ever met (yes I have the war stories), he was smart enough to put our group on the first network so we could communicate via email. Still, he was one of the biggest complainers when we went to CAD and computer went up as a result.

As a general observation I have to say that using a computer to do the scutwork never, never, NEVER relieves the engineer of making sure the work is right. Like Capt Moosie, when I write an Excel spreadsheet I usually check it at least once by doing a hand calculation.

If people only knew that those engines were designed on Augie and Rays'.

Not sure what Augie and Ray's is.....

Yep, it is surprising how reliable engines are, given some of the work methods I saw. Primitive and time-consuming at best, so I know why back when I was there in '87 - '89 Pratt had to spend 30% more than GE to produce the F-100 military engines.

The chilie hot dog stand on the other side of the fence at the south engineering building. Do engineers with heartburn design good engines?

I don't remember a hot dog stand there. I seldom went off-property for lunch....I ate in the cafeteria. But they could still give out a mean case of heartburn so I guess engineer with it can still do good work.

BTW, it's amusing that we both worked at Pratt, although at different times, and now we live close togehter. I am near King of Prussia Mall.

Went through there 4 years ago and had to have a dog. Still just as deliciously awful as I remembered it. I'm glad their sauce is a secret. I wouldn't like to run into it somewhere by surprise.

The complex was only a shadow of its former self. Half the buildings gone, a sports stadium in the middle of the airfield next to a sporting goods store, I think Cabelas. Parking lot was only 1/4 full. and no landing strip evident. I watched a 747 land there once. Needed every inch and had to back up from the fence to turn around. Used to do closed circuit TV set-ups for the laser labs out back and in the Wilgoose labs high altitude chamber and as needed elsewhere. We had one of the first commercial color Sony video tape systems. I was in instrumentation from '69 until the '72 layoff and then brought back in '73 in turbine temperature controls until the next layoff in '75. Got tired of all that and got a steady job...bartending.

I don't think a lot of people realize the stress that engineers work under..............................often without the pay that should go with it.
Amen!

Many years ago, I took my car in for service and my mechanic rolled out his brand new (dyno-tune?) (electronic analytical cart) and went to work. He was not a ((rocket surgeon)), but he had been a successful auto mechanic for a relatively long time, without having any college education. A while later, he told me what the problem was, and what it would take to fix it in terms of time, parts and labor. I then agreed to having him do the work, but I also thought to ask him if he thought his new machine would replace very many mechanics? In short, he said that his machine is no better than the person who operates it...

The repair was great because he did his usual high-quality, conscientious, job, in his usual pains-taking way, as opposed to many other auto mechanics. His machine was just one of his many tools with which he was an expert. It was not a substitute for experience, judgement, or actual ability, nor was it a (mechanical crutch) to him...

Time has progressed, new (machines) have come along, but human behavior seems to have stayed the the same.

Now the same principle applies, these days, to such projects as a roof design being analysed by an apparently exotic computer program, and being operated by (bean-counters, etc.)...

After all the years, that mechanic, by the way, is still one of the most effectively smart guys I ever met...

This thread brings back memories, as far as good management and engineering practices concerns. I have yet to find something to disagree with, but can add some.

The Hyatt case is simple and instructive. The more than one level suspended walkway was specified for individuals walking to the elevator built in the opposing wall. The partying, dancing crowd was not considered, nor labeled against (as if that matters in such a situation!). The original design was impossible and quizzical. Clearly not thought thru for machineability, nor for the need for that "originality". It supposed to have a fattened and threaded portion (?!?) to hold up a floor. In real life it is impossible to make. So the builder cut it, and connected the upper with the lower by an intermediary. Thereby cutting its carrying capability roughly by half. Dynamic dampening, what dynamic dampening?

Was it needed? NO. There is a self tightening wedging clamping system used at suspension bridges both for hanging the road elements and anchoring the main cables. As you know, it is reliable. Why was not that used in the primitive Hyatt case? Your guess is as good as mine, but technical it ain't.

The sport stadium case culprit is again most likely primitive thinking on the part of the decision makers. I cannot talk meaningfully about the overload factors. But I have definite opinions of the design. It was not modular, nor did it have designed-in redundant load pathways. Why is that important? It is not, until you need to remove and replace a corroded / cracked module under load. As you started that work, the stadium roof was ready to collapse under load.

That is the reason, that the saddle form tent roofs, supported by 2 (or4) main column, and cables gains support. Snow and slush cannot collect on most parts, but slide off, automatically. Some designs are inherently better, not relying on ignoramuses managing properly, grossly flawed designs.

Actually, the Hyatt regency skywalk collapse was due to the suspender rods not being aligned where they met at each of the 2 levels, thus a moment was introduced into the steel bracket where it was attached to the floor girder at each level. Each bracket was not design for this moment, only shear introduced by the axial tensile load in the hanger.

Simple error that both the design engineer and the steel fabricator missed, or failed to recognize the statics actually involved.....forgetting about moment couples has doomed many a good engineer. This should be considered a lesson learned.

Of course the dancing bodies on each suspended walkway introduced dynamic loading, which exasperated the overloaded shear brackets.

We can be as careful as we possibly can.

Sh*t happens. No one has the recipe to prevent it.

Remember when the Computer was asked, in effect, (( what can go wrong with this? )),

And the Computer (replied) ''Nothing can go wrong. ...go wrong. ...go wrong. ...''

Well, something did go wrong, again, ...and again, ...and again, ...and again, ...

Exactly. I'm getting a little foggy, but I think they call it Murphy's Law. I think Murphy was the first man to forget his anniversary. From that day forward, all men are screwed.

It was rarely the computer, it was mainly the operators that screwed things up.

Garbage in, garbage out.

Some interesting, related reading:

http://failures.wikispaces.com/C.+W.+Post+College+Auditorium+Collapse

That was a most interesting article Mark, thanks!

Back in the late 70's when I started my career working for a Structural Engineering firm (I worked there for 12 years, including part-time during community college, then College Co-Op periods, and after earning my BSCE), the principal of the firm purchased the newly revised ANSI A58.1 code (later changed to ASCE Standard 7) that dealt with snow drifts and unsymmetrical snow loading on roofs. That was a steep learning curve and long overdue. We have come a long long way since then regarding the design of roof systems, especially in the snow belt!

People think I'm on CR4 just to give people a hard time. True.

I also use CR4 like a little whore that prompts me into further reading on various subjects.

I'm a bit of an information junkie. Wife doesn't like it.

Most wives don't like that.......... LOL

Well I'm outta here for a long weekend....off to the Jersey Shore (Asbury Park, home of Bruce Springstein and the E-Street Band.)

Sometimes it is not the design engineer. I designed/built this cage 6 years ago, it has taken the worst that a steel mill can dish out. I rated it at 26K lbs and here there is 32K lbs loading. I cannot design for stupid.

Hey, talking about design failures..................the Japanese forgot to plan for a 30' wave washing over their nuke plant.

Therefore, nuclear energy is bad.

I may have mentioned this before....................but sh*t happens. It doesn't mean it's time to stop trying.

Recently, I saw a iapanese program going into bloody detail in the likely tectonic plate slip, facing the southern portion of the islands. This, in likelihood will cause twice (60") of the wave hight (and 8x of the wave energy?) of the Fukushima one. The citizens discuss not only the power plants, but coastal settlements.

The issue is applicable for the whole Pacific Ring of Fire from southeast Asia thru Alaska, California, to the southern tip of South America.

It appears, this is a continouos learning curve, leading to all sorts of upgraded codes. Pushing the dividing line of what is avoidable, and what insurance calls "act of god" as unforeseeable and unavoidable.

There is so much here, so many posts to which to respond.

Like Moosie I am a structural engineer, although I have retired; structural engineers still part of the general discipline, civil engineers. The sub-disciplines require increasing knowledge and experience to the point that it is almost impossible to be an old fashioned generalist; just learning and keeping up with the changes to the codes and mandatory specifications requires a major effort.

Also, like Moosie, I cringe when these events occur, but some are inevitable as we "push the envelope", some of what I will write here, I have posted before but it is as relevant to this as it was before.

The first one to which I was introduced was the Tay Bridge disaster as with others to come, there were multiple things wrong but did not necessarily have anything to do with the collapse. The learning curve: Up till then there had been no requirement to design for wind; a requirement was added. If you take a good look at the buttresses of some of Europe's Gothic cathedrals you can see that the originals were failing and they were modified several times, again, the learning curve.

I sometimes feel that even with a degree, engineers need the equivalent of a formal apprenticeship. It won't happen because design companies are separate from fabrication companies are separate from construction companies, more's then pity, and to arrange for a young Engineer In Training to spend time with each costs money. The result is that field RFIs doesn't get the response they need. I always responded quickly even if it was to say it would take more time than the standard. My motive was as much selfish as anything; I didn't want the field giving me a horrible mess with their own "solution". I used to get annoyed when they asked to change something and then got shirty when I refused, I tried to get them to simply state the problem and let me look for the best solution.

In one case, I designed the structure for a mall; it was in an area with old sewage piping so the roof was designed as a delay pond by using limited throat drains, the design storm of 4" of water to drain off in 24 hours. To protect my roof I put scuppers around the wall at +4". I moved to a different company, but an inspector on the site, tracked me down, the contractors want to move the scuppers to 12", is that okay?". I said "No" and explained the consequences. If he hadn't taken the trouble to track me down... years later some of the drains clogged and water came from the scuppers.

On the same mall, the client's PM got a bootleg copy of my preliminary design sketches and was very upset when the drawings had heavier joists and beams; he had obtained a rough price from my sketches and told his master in the company. I explained that he had stolen the strength design before I could check it for vibration, "What vibration?" "People walking in step" "But they don't walk in step" "Send us a letter stating that there will never be a marching band and cheerleaders doing a promotion, or a rock group, or any other such event." My design stayed.

Another important building, I had the basement walls moment connected to the ground floor, this leads to some rebar congestion, plus anchor bolts had to be installed at intervals for the steel framed building above. In the old days, I would have put a note on the drawing that the bolts must be placed at the same time as the rebar but we were no longer allowed to interfere with "means and methods". One of my young engineers went to the site and called up to say that they had cut the hooks off the bars to get the bolts in. They swore that it was the first time but I wonder how slim are the margins. We had them weld the ones we knew about. A collapse into that basement would have been spectacularly newsworthy

On computers: I started work as a drafting room clerk in 1951 so I have seen the rise of computer design programs. The big difficulty in the beginning was that they couldn't properly model the structure. There are six degrees of freedom for the end of any member, it can rotate about the three orthogonal axes and move along them. Each member has two ends and they connect with other members. Each member affects the other members so when you try to put all of the members in a structure together it leads to a huge number of simultaneous equations. The ability to do this has grown with increasing computing power. A further problem during the teething stages was that new grads who knew least about the design of structures knew the programs from college, but the experienced people who understood structures, didn't know the programs. The result was that to get the computer model to work, the youngsters tweaked it here and there and made it less and less of a real model of the actual structure.

I just heard somebody repeat, in a military context, Mark Twain's "Nature does not repeat itself but it rhymes" We could apply it this subject as much as any other.

P.S. The Hyatt had a continuous rod in the original design but the fabricator and/or the erector changed it and the change was accepted without comment. They could have used coupling nuts and followed the original design but that might not have held the dancing hoard.