Posted by Franz [24.149.37.138] on Thursday, December 24, 2015 at 15:04:17 :
In Reply to: Re: steel in wtcs. form article on construction posted by mannyc [96.224.210.179] on Thursday, December 24, 2015 at 08:24:23 :
From my recall compromises were made in construction of Nelson & David to achieve the desired height. One that particularly stands out was the use of light weight concrete and 4" decks to minimize weight to gain height. This involved tradeoffs from traditional NYC methods including minimization of huge rooftop water tanks replaced by high pressure pumps in the basement to get water to the top as well as alternate AC systems.
The compromise was considered acceptable at time of construction, justified by the planed use solely as offices, and restricting use of office furniture such as heavy safes. Other compromises such as elevator shafts with drywall walls only rather than traditional construction were also implemented. Funny part was nobody calculated the weight of paper in file cabinets into the design.
I also recall there was some retrofit of the towers for sway damping after a hurricane demonstrated excessive sway.
After the basement bombing, an Engineering report was done on the structural integrity of the towers, including ability to withstand attacks to come in the future. Part of that study involved the potential of a plane flying into the tower, somebody actually remembered the bomber that hit the Empire State Building. The specs for the study were vaguely written in terms of "Plane hits building" to the extent people conducting the study requested clarification on size of plane. Port Authority specified a small general aviation plane after discussion revealed such could hit either tower with the tower surviving, but neither tower could or would survive a hit by a small commercial jet. The light weight floor construction came back to bite designers in the ass. In terms of potential survival of aircraft strike, the report was written very vaguely.
It is entirely possible that the Port Authority Report was read and studied by members of a very large Saudi construction company. It is also very possible that large numbers of foreign Engineering Students recognized the potential watching hours of building implosion demolition shows on TV prior to the jets flying into WTC. Oddly such shows went off air not long after, possibly locking the barn door after the horse left.