The Empire State Building is a 102 storey, 1,250 feet tall building located between the Fifth Avenue and West 34th Street in New York; with an office space of 2.8 million square feet.
It was constructed in 1931and stood as the tallest building in the world until 1971 when World Trade Center was constructed although; it reclaimed the tallest building in the world in 2001 after the destruction of the World Trade Center. It was designed by William Lamb and was constructed began in1930 and completed in 1931 by Starrett Brothers and Eken Contractors.
The landmark’s outside design is made from Indiana limestone, which is eight-inch thick. The floor slabs are eight-inch thick, made up of one-inch cement layer and seven-inch of ember and concrete. All columns, girders and floor beams were made of steel sheathed with 1-2 inches of brick terracotta and concrete.
There was almost no spacing between the floors and there were no air vents for air circulation penetrating fire extensions, floors and ceiling, with each floor having its own HVAC system. The elevator and utility shafts were masonry bolted together and in the fire escape there was a four inch brick enclosed. This was designed to allow occupants to escape in case of fire through the staircase without fire filling up the escape space.
On July 28, 1945, a fateful B-25 Mitchell bomber crashed on the building causing the building to burst into flames. Although it did not collapse it was seriously damaged. This is due to the strong and rigid steel frame structure on the center of the building. If we were the engineers of the Empire State Building we would reduced the size of the open floor design by, rather than using a center core steel column, we would use a skeleton steel frame. Also we would have used a thicker layer of concrete on the floor of about 2-3 inches.
The world trade center was an office complex with a 13.5 million square feet located in Lower Manhattan in New York City until September 11th 2001 when it was destroyed by terrorist attack. The blueprint of the World Trade Center was designed by M. Yamasaki as chief architect and Emery Roth & Sons as associate artichects, in 1962 through a tube frame design for the 110 storey building. The towers were constructed between the years 1966 – 1971.
The tube frame design allowed open floor plans instead of columns apportioned across the interior to support the tower load. The tube frames was protected by a spray on fire resistant material that provided a lighter structure which could move sideways when wind blew. Although this was the main cause of the collapse of the World Trade Center, this design is unlike the Empire State Building which was constructed using thick, heavy materials for fireproofing of the steel materials.
The World Trade Center was constructed with strong load-enduring steel columns that were closely located to each other to form a strong, tough wall design supporting all sideways weight, for example, wind weight and sharing gravitational pull. Beside modules were connected with the splices at the middle span of the column and spandrels.
The elevators, utility shafts, staircases, lounge rooms and other facilities were located at the center of the towers. The design included building veneer covered with aluminum alloy. The design used a system with sky lobbies where people could change floors from high capacity express elevators. This made the local elevator to located in the along the same elevator shaft. The towers were designed with narrow office window openings 18 inches wide.
If were the engineers in the World Trade Center we would propose the project to be put in a less congestion location since the serenity of the building was not appropriate, it disrupted traffic flow in Manhattan and many chaos. Also we would have changed the light weight bar joist as it could not sustain the load of the towers if exposed to an about ten minutes in fire. We would have put heavyweight bar joists.