24 Feb 2007, 10:13 pm
TheMachine1
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Joined: 11 Jun 2006
Gender: Male
Posts: 8,011
Location: 9099 will be my last post...what the hell 9011 will be.
24 Feb 2007, 10:52 pm
25 Feb 2007, 12:40 am
25 Feb 2007, 10:25 pm
Jacob_Landshire wrote:
Note the amount of steel framing (top pic) that went into the World Trade Towers. That steel was bolted and/or welded together during construction.
Wow, that's awesome proof, man!
How could steel fail?! After all isn't Superman the Man of Steel! Superman is way more powerful then any concrete core!
Yeah! After all, remember when the Bush Administration bombed the Tacoma Narrows bridge?
26 Feb 2007, 7:37 am
jimservo wrote:
Yeah! After all, remember when the Bush Administration bombed the Tacoma Narrows bridge?
resonant frequencies!! !!
26 Feb 2007, 10:20 am
jimservo wrote:
Yeah! After all, remember when the Bush Administration bombed the Tacoma Narrows bridge?
Damn you Bush!! Stop destroying our bridges!! !
26 Feb 2007, 10:30 am
TheMachine1
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Joined: 11 Jun 2006
Gender: Male
Posts: 8,011
Location: 9099 will be my last post...what the hell 9011 will be.
26 Feb 2007, 1:46 pm
26 Feb 2007, 2:07 pm
I believe it was the CitiGroup Center (the famous skyscraper on stilts in Manhattan). I think I saw the same program as you, TheMachine1.
NOTE: The image has the old name of the building.
From Wikipedia:
Quote:
Changes during construction led to a finished product that was structurally unsound. In 1978, prompted by a question from a student, LeMessurier discovered a potentially fatal flaw in the building's construction: the skyscraper's bolted joints were too weak to withstand 70-mile-per-hour (113 km/h) wind gusts at specific angles.
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.
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 catastrophic failure due to bolt failure. 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 16 years.
LeMessurier reportedly agonised over how to deal with the problem - making it known to the wider world risked ruining his professional reputation. But with hurricane season fast approaching, he took the bold decision to approach Citicorp directly, and advise them of the need to take swift remedial action. He convinced Citicorp to hire a crew of welders to repair the fragile building without informing the public, a task made easier by the press strike at that time.
For the next three months, a construction crew welded two-inch-thick steel plates over each of the skyscraper's 200 bolted joints during the night, after each work day, almost unknown to the general public. Six weeks into the work, a major storm, Hurricane Ella (1978 Atlantic hurricane season), was off Cape Hatteras and heading for New York. With only half the reinforcement finished, New York City was hours away from emergency evacuation. Luckily, Ella turned eastward and veered out to sea, buying enough time for workers to permanently correct the problem.
Despite the fact that nothing actually happened as a result of the engineering gaffe, the crisis was kept hidden from the public for almost 20 years. LeMessurier's act of alerting Citicorp to the problem inherent in his own design is now used as a textbook example of ethical behavior.
After the modifications of the bolted members were completed, the building is now generally considered to be one of the most structurally sound skyscrapers in the world.
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.
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 catastrophic failure due to bolt failure. 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 16 years.
LeMessurier reportedly agonised over how to deal with the problem - making it known to the wider world risked ruining his professional reputation. But with hurricane season fast approaching, he took the bold decision to approach Citicorp directly, and advise them of the need to take swift remedial action. He convinced Citicorp to hire a crew of welders to repair the fragile building without informing the public, a task made easier by the press strike at that time.
For the next three months, a construction crew welded two-inch-thick steel plates over each of the skyscraper's 200 bolted joints during the night, after each work day, almost unknown to the general public. Six weeks into the work, a major storm, Hurricane Ella (1978 Atlantic hurricane season), was off Cape Hatteras and heading for New York. With only half the reinforcement finished, New York City was hours away from emergency evacuation. Luckily, Ella turned eastward and veered out to sea, buying enough time for workers to permanently correct the problem.
Despite the fact that nothing actually happened as a result of the engineering gaffe, the crisis was kept hidden from the public for almost 20 years. LeMessurier's act of alerting Citicorp to the problem inherent in his own design is now used as a textbook example of ethical behavior.
After the modifications of the bolted members were completed, the building is now generally considered to be one of the most structurally sound skyscrapers in the world.
(source link)
27 Feb 2007, 12:10 am
27 Feb 2007, 2:03 am
27 Feb 2007, 3:34 am
27 Feb 2007, 11:53 am
27 Feb 2007, 6:29 pm
28 Feb 2007, 11:50 pm
01 Mar 2007, 5:36 pm
