Disaster in Kansas City: Lessons Learned from an Engineering Failure

Wonder if they did all their homework.

What transparent material can withstand the tension stress when spanning buildings supporting a swimming pool?

Ideas?

Why would anyone want to swim in a pool that was only 4 feet deep is beyond me. In the commercial pools I serviced and repaired, the shallow end was separated from the deep end by a rope with floats attached. A swimming pool that is only 4 feet deep is commonly called " A kiddie pool ". Generally a 4 foot deep shallow end is reserved for beginning swimmers or non-swimmers. $972,000 for a flat with a kiddie pool seems pointless.

As for the Kansas city snafu, I was still in high school at the time, and I can't say if I followed the story that keenly. Seeing the picture of the rusty nut, washer and rod first strikes me as someone using low quality materials and didn't they have welders in 1978 ? Wouldnt welding the flanges to the rods of been a stronger bond than using a $ 2.00 nut and washer ? They should of gave them some time in the big house for being cheap bastard's, if anything.

4 feet is deep enough for a 'lap pool,' if it gets deeper at the ends. And considering that this is part of an apartment structure for the 'wealthy elite,' it's not likely to have kids frolicking in it, rather, the Elite with 'runway bodies' will be out there doing laps in the pool, not only to keep their 'perfect bods,' but also to BE SEEN showing off their perfect bods.

It doesn't need to get deeper at the ends; you can easily do a flip turn in 3 feet of depth. Though in the pool in question, it doesn't matter: one end is stairs.

And I think that being practical about a transparent pool that spans the street is kind of missing the point. It's not there to be practical, it's there to be cool.

"It's not there to be practical, it's there to be cool."

That's the point I was trying to make, and trying to make guesses about what practical aspects of the pool there are.

The forensic mavens in our field (structural engineering) have commented that "most" structural failures (esp. steel and wood) occur at "connections", as was the case of the KC skywalk failure with a "punch out" of a one or more of the hanger rods on the flange of the deck framing member. The number of people on the structure was determined to not likely have exceeded the code-required design loading.

Robynn, thank you for a very concise and well written article. An engineering analysis of this tragedy is an excellent teaching tool, and a reminder of what can actually happen in the real world, for every structural engineering student and practicing engineer alike.

This failure happened while I was attending college for my BSCE in Civil Engineering. Several of our Professors discussed in-depth the reasons for this failure (on all levels), especially the Change Order that affected the suspension rods at the ends of the built-up channel section: the resulting eccentric loading, which wasn't checked by the Engineer-of-Record, that was introduced into the built-up section acting as the primary mode of stress failure.

Throughout my college education (and during Co-Op stints), I had worked for a small structural engineering firm in Albany NY. No way would our office had approved such a Change Order without first performing a thorough analysis of the connection as proposed by the G.C. and his steel Fabricator.

Frankly, I've never liked built-up structural steel members, such as what was used in this case. It would have been much better to have incorporated a Wide Flange beam section with the necessary stiffening elements in the vicinity of the suspension rods, as well as providing in-line threaded and bolted connections for each rod, thus eliminating the eccentricity problem.

Signed,

Captmoosie, PhD, NYS P.E.

Many other engineering failures are covered in the OH CR4P! blog. Hopefully by studying these disasters, future engineers can learn from past mistakes. The trick is to avoid making new mistakes at the same time!