In particular, the 8-story-high diagonal parts were done in multiple splices that were supposed to be welded together but ended up being bolted together. It sounds like it made things much worse.
The builders did not notify the designers of the change, and 114 people were killed as a result.
[1] http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse
The thing is, that design would have been a horrible pain to build as designed. It's a design failure. To build it, you'd need to slide a large steel section up two screws, following it by a nut up 30 feet. It needed to be redesigned by someone who knew more about fabrication and erection, and then checked closely to make sure that there weren't material changes in the performance.
This is fascinating, but I feel that I'm missing some terminology and concepts. I wonder if you could explain in more detail and clarify the terms?
From the part I do understand, it reminds me a lot of what I've encountered in a recent software project or two.
A company hires a visual design consulting firm for hundreds of thousands of dollars, and boy do they get their money's worth. Beautiful images and designs, complete with high quality videos with things moving all over the place in the smoothest and most seamless way.
And not a thought toward how this fantastic beautiful design would actually be implemented. No consultation with the programmers to see what could actually work given the required technology.
Agile? That's for programmers. When it comes to the product design, the visual designers have spoke, and that is that. It's waterfall time, baby!
On one project the designers decided it would be beautiful to have menus and controls that would slide out and overlap a Google Earth plugin. Great idea! Until you realize that it would take three solid months to work out all the cross-platform bugs in that approach. Three months that could have gone into building something useful, something that customers actually cared about.
When I worked as a CAD operator for a company which fabricated glass doors and windows, I would often receive printed drawings from architects. Soft copies were not available, as the architects considered their designs to be proprietary. But of course we the fabricators would benefit from having the design in CAD so we could produce different views and so on.
One day I received a set of drawings for a three-dimensional arrangement of glass sort of like a bay window. There were plan (overhead) and elevation (side) views, and I stared at those for a while, unable to make a coherent 3D model to match them. I then took some cardboard and cut it out in the shapes shown on the drawings. The shapes did not actually fit together--any way you tilted the pieces, there would be unworkable gaps in some part.
This was at the time when a lot of drawings were still made in 2D, with manual work to align the different views. I ended up having to visit the other firm's office, my cardboard cutouts in hand, to show them that what they had drawn could never be built.
So, the atrium was (say) 80 feet tall, with the sky bridges every 20 feet. So one at 20, 40, and 60 feet. If the continuous rod that had been specified in design was used, it'd be a little longer than 60 feet long (80 foot ceiling, lowest bridge 60 feet below that, plus a another foot or so to make room for fasteners).
That would mean that the middle bridge would have to have had the nuts spun along 40 feet (either from the top or bottom) and the nuts for the topmost and bottom-most bridge would have to be spun along 20 feet of thread. But before you could put the topmost nut on, you'd have to support the rod as you placed it through the box-section beams for the middle bridge. And then do the same for the topmost beam. And then lift it all so that the top end of the rod could be secured to the ceiling.
And this wouldn't have been one rod at a time -- you'd have to do the same for all dozen or more rods at the same time. Nightmare from a construction schedule standpoint.
1. There may be problems with that approach. IANAPE. They would be different problems than actually caused the failure.
[1] http://www.amazon.com/To-Engineer-Is-Human-Successful/dp/067...
I did a version in plain text and they ended up offering me a job.
This mean in Brazil there is a lack of experienced and honest engineers (the scumbag ones know how to not get shafted, the honest ones go to other countries, and the non-experienced ones... well, more meat for the grinder).
Earlier in May, LeMessurier met for an inquiry on another job where he mentioned the use of welded joints in the Citicorp building, only to find a potentially fatal flaw in the building's construction: the original design's welded joints were changed to bolted joints during construction, which were too weak to withstand 70-mile-per-hour (113 km/h) quartering winds. While LeMessurier's original design and load calculations for the special, uniquely designed "chevron" load braces used to support the building were based on welded joints, a labor- and cost-saving change altered the joints to bolted construction after the building's plans were approved. Base of the Citigroup Center View from the street
The engineers did not recalculate what the construction change would do to the wind forces acting on two surfaces of the building's curtain wall at the same time; if hurricane-speed winds hit the building at a 45-degree angle, there was the potential for failure due to the bolts shearing. The wind speeds needed to topple the models of Citigroup Center in a wind-tunnel test were predicted to occur in New York City every 55 years. If the building's tuned mass damper went offline, the necessary wind speeds were predicted to occur every 16 years.