Posted by ngon nguyen on October 01, 2001 at 10:40:30:
In Reply to: Re: Progressive collapse of Twin Towers posted by Paul Dremann on September 30, 2001 at 05:51:17:
Thank you for your response. Most people thought damper system is a redundant system. For WTC, it is not a redundant system! It is an integral and an essential part of their lateral resistance system. After this system is out, under the vortex shedding of a morning breeze, Twin Towers gallop…. Any one involving in the design of a stack would understand this galloping effect.
As a student for more than 3 decades now, I often raise my concern about the fireproofing of these dampers. However, from UC Berkley to SUNY at Buffalo, people who promote these devices often ignore it as an unlikely event because of the difficulties in fireproofing these devices and in allowing them to move at any time also.
PS: I will email my write-up to you now.
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