How architect designed building to withstand plane crash last week.

Though architect, Frank Williams, never dreamed the Bellaire condominium he designed on East 72nd Street would ever have to withstand a single engine plane slamming through its core at 122 mph like it did October 11, he had designed the building to hold up under pressure.

Prior to construction of the building, Williams' engineers performed several tests, including wind tunnel tests determining the 50-story condominium building would not bow under even the most vicious gale force winds striking off the East River. He built in accordance with safety standards set for earthquakes, created enlarged fire escape staircases and added extra fire hoses, features that were not made mandatory until new building codes were introduced following the 9/11 terrorist attacks.

Most importantly, the building struck by the Cirrus SR20 single engine plane carrying baseball player, Cory Lidle, and a flight instructor, was constructed from reinforced concrete--steel rods cocooned in concrete--a material that has remarkable staying power during a fire.

The reinforced concrete used in the construction of the Bellaire is typical of the majority of residential buildings in New York City and the relatively minor damage sustained there during the crash that claimed the lives of the two men bodes well for the rest of the city's high-rise homes, according to those in the industry.

"Safety has always been a concern," Williams told REW this week. "Long before 9/11, it was standard practice when you have a residential building where people are spending the night that everything that goes into the building will not burn. You can't really have a major fire today in a good reinforced concrete building."

Antonio Argibay, AIA, principal of Meridian Designs Associates, agrees that the Bellaire withstood the crash because it was made of reinforced concrete.

"In terms of impact, the small plane was basically a car with wings. It took a bit of brick down on the facade, which is what you'd expect if a car hit a building. The threat was really in the large amount of fuel that crashed," Argibay said. "Reinforced concrete has an inherent passive resistance to fire. It could burn for hours."

Agribay cited the catastrophic fire in the 32 story Windsor Tower in Madrid, Spain, last year as an example of the remarkable resistance of reinforced concrete during a fire. The fire raged for over 26 hours, eating up combustible material inside the building. The steel parts of the building went limp, like a wet noodle. However, the majority of the building--constructed out of reinforced concrete--remained standing.

"Reinforced concrete is one of the safest options," said Alfred G. Gerosa, president of the Concrete Alliance. "It can withstand temperatures proven to be resistant to fireballs. I think you can get it heated above 1200 degrees and have it hold up for a while."

Most residential buildings in the city are constructed from reinforced concrete because it is quick to construct and lends itself well to designs where there is a lot of repetition of floors, Agribay said. Buildings constructed from steel usually have a fireproofing spray-on material applied to the steel, however, the steel itself can lose elasticity and become deformed within a very short period of time in the event of fire.

When the planes struck the WTC on 9/11, the heat generated by the burning tanks of jet fuel caused the steel in the two towers to buckle and melt, leading to the collapse of the buildings.