Re: Acciaio e temperatura: ma il tempo?
Inviato da Henry62 il 24/8/2006 9:30:00
Ciao,
alcune considerazioni prese da questo sito:
http://vincentdunn.com/wtc.html
in particolare segnalo il paragrafo:
Concrete removal
Since the end of WWII builders designed most of the concrete from the modern high-rise constriction. First concrete they eliminated was the stone exterior wall. They replace them with the “curtain walls of glass, sheet steel, or plastics. This curtain wall acted as a lightweight skin to enclose the structure from the outside elements. Next the 8-inch thick concrete floors went. They were replaced with a combination of 2 or 3 inches of concrete on top of thin corrugated steel sheets. Next the masonry enclosure for stairs and elevators were replaced with several layers of sheet rock. Then the masonry smoke proof tower was eliminated in the 1968 building code. It contained too much concrete weight and took up valuable floor space. Then the solid steel beam was replace by the steel truss. And finally the concrete and brick encasement of steel columns girders and floor supports was eliminated. A lightweight spray-on coating of asbestos or mineral fiber was sprayed over the steel. This coating provided fireproofing. After asbestos was discovered hazardous vermiculite or volcanic rock ash substance was used as a spray-on coating for steel. Outside of the foundation walls and a thin 2 or 3 inches of floors surface, concrete has almost been eliminated from high-rise office building construction. If you look at the WTC rubble at ground zero you see very little concrete and lots of twisted steel.
Ciao
alcune considerazioni prese da questo sito:
http://vincentdunn.com/wtc.html
in particolare segnalo il paragrafo:
Concrete removal
Since the end of WWII builders designed most of the concrete from the modern high-rise constriction. First concrete they eliminated was the stone exterior wall. They replace them with the “curtain walls of glass, sheet steel, or plastics. This curtain wall acted as a lightweight skin to enclose the structure from the outside elements. Next the 8-inch thick concrete floors went. They were replaced with a combination of 2 or 3 inches of concrete on top of thin corrugated steel sheets. Next the masonry enclosure for stairs and elevators were replaced with several layers of sheet rock. Then the masonry smoke proof tower was eliminated in the 1968 building code. It contained too much concrete weight and took up valuable floor space. Then the solid steel beam was replace by the steel truss. And finally the concrete and brick encasement of steel columns girders and floor supports was eliminated. A lightweight spray-on coating of asbestos or mineral fiber was sprayed over the steel. This coating provided fireproofing. After asbestos was discovered hazardous vermiculite or volcanic rock ash substance was used as a spray-on coating for steel. Outside of the foundation walls and a thin 2 or 3 inches of floors surface, concrete has almost been eliminated from high-rise office building construction. If you look at the WTC rubble at ground zero you see very little concrete and lots of twisted steel.
Ciao
Messaggio orinale: https://old.luogocomune.net/site/newbb/viewtopic.php?forum=4&topic_id=1908&post_id=43843