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One point that this article doesn't mention but the video does (starting about here: http://www.youtube.com/watch?v=TZhgTewKhTQ#t=350 http://www.youtube.com/wat

One point that this article doesn't mention but the video does (starting about here: http://www.youtube.com/watch?v=TZhgTewKhTQ#t=350 http://www.youtube.com/watch?v=TZhgTewKhTQ#t=350) is that the building wasn't built exactly as designed. 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.

pat2man 12y ago
The fix was to rip the building apart and weld everything together.
- kevinchen 12y ago
  According to wallflower below, it was to weld thick steel plates to the joints. That's not the same as following the original design.
jzwinck 12y ago
This reminds me of the 1981 Hyatt Regency walkway collapse [1]. The blueprints called for continuous suspension rods with walkways attached along their length. This would mean that the load on any single joint between rod and walkway would be limited to the load on one walkway. But as built, the rods were not continuous, rather they connected each walkway to the one below. This meant the load on the topmost rod-walkway joint was the aggregate of the load of all walkways hanging below it. 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 http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse
- wiredfool 12y ago
  And not only that, instead of using a box section for the steel piece, they used two c sections welded together like this: []. A box section is strong, that built up section, not so much. 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.
  - Stratoscope 12y ago
    > To build it, you'd need to slide a large steel section up two screws, following it by a nut up 30 feet. 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.
    - jzwinck 12y ago
      Yes, physical construction and software construction can have some of the same communication difficulties between designers and builders. 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.
- speeder 12y ago
  My father is engineer, once he was renovating a shop in a intersection, he told the builders to use five tree trunks to hold the second floor while they demolished and rebuilt the first floor merchandise display. The builders decided to use only three, and pocket the money of the other two to themselves, and the building fell, thankfully my father had started working before signing the contract, so he could not be sued.
  - serge2k 12y ago
    Can you sue the engineer if the builders don't follow the spec?
    - speeder 12y ago
      On Brazillian law the engineer is held responsible for everything that can go wrong, unless he proves it was not his fault... 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).
- sokoloff 12y ago
  Apropos: http://www.britannica.com/blogs/2009/10/the-classic-tree-swing-example-of-production-and-customer-service-gone-awry/ http://www.britannica.com/blogs/2009/10/the-classic-tree-swi...
stox 12y ago
https://en.wikipedia.org/wiki/Citigroup_Center https://en.wikipedia.org/wiki/Citigroup_Center 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.

pat2man 12y ago

The fix was to rip the building apart and weld everything together.

kevinchen 12y ago
According to wallflower below, it was to weld thick steel plates to the joints. That's not the same as following the original design.

jzwinck 12y ago

This reminds me of the 1981 Hyatt Regency walkway collapse [1]. The blueprints called for continuous suspension rods with walkways attached along their length. This would mean that the load on any single joint between rod and walkway would be limited to the load on one walkway. But as built, the rods were not continuous, rather they connected each walkway to the one below. This meant the load on the topmost rod-walkway joint was the aggregate of the load of all walkways hanging below it. 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 http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

wiredfool 12y ago
And not only that, instead of using a box section for the steel piece, they used two c sections welded together like this: []. A box section is strong, that built up section, not so much. 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.
- Stratoscope 12y ago
  > To build it, you'd need to slide a large steel section up two screws, following it by a nut up 30 feet. 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.
  - jzwinck 12y ago
    Yes, physical construction and software construction can have some of the same communication difficulties between designers and builders. 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.
speeder 12y ago
My father is engineer, once he was renovating a shop in a intersection, he told the builders to use five tree trunks to hold the second floor while they demolished and rebuilt the first floor merchandise display. The builders decided to use only three, and pocket the money of the other two to themselves, and the building fell, thankfully my father had started working before signing the contract, so he could not be sued.
- serge2k 12y ago
  Can you sue the engineer if the builders don't follow the spec?
  - speeder 12y ago
    On Brazillian law the engineer is held responsible for everything that can go wrong, unless he proves it was not his fault... 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).
sokoloff 12y ago
Apropos: http://www.britannica.com/blogs/2009/10/the-classic-tree-swing-example-of-production-and-customer-service-gone-awry/ http://www.britannica.com/blogs/2009/10/the-classic-tree-swi...

stox 12y ago

https://en.wikipedia.org/wiki/Citigroup_Center https://en.wikipedia.org/wiki/Citigroup_Center 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.