What risk was that? These buildings took a direct hit from airliners weighing 450,000 pounds, going 500 miles per hour. At impact, this exerted a force of 632 million ft-lbs at the 70th floor. Neither building snapped at the bottom or even swayed.
What brought the buildings down was fire, primarily caused by the jet fuel. The melting point of steel is about 1600 degrees C. The flame temperature of kerosene (jet fuel) is 1700 degrees C. No steel structure of any kind could have withstood a fire fueled by 24,000 gallons of jet fuel. That they stood as long as they did, giving time for thousands of people to escape, tells us that these buildings were strong indeed. When they failed, they failed exactly the way they were supposed to... straight down. Can you imagine the death toll if buildings that size had fallen over sideways, crashing into other buildings on the way down?
The architect and the structural engineers deserve a round of applause, not approbation.
The WTC towers were very controlversial. They used a new structural method in which the floors were suspended only at the periphery and at the elevator core. There were two alarms given even before the buildings were completed.
First, there were published articles in engineering journals saying that failure of the trusses of a single floor or of the connections of a floor to its supports would cause pancaking of all floors below it in a process that would bring down the entire building. This is almost certainly what happened as seen from the videos of the buildings' collapse.
Second, the use of asbestos to cover the steel and protect it from the heat of a fire was stopped (by environmental regulations) when the buildings reached 70 stories high. The man doing the asbestos installation, named Levine, correctly and precisely predicted that a major fire above the 70th floor in either building would bring down the entire building secondary to weakening of the relatively light steel trusses carrying the floor spans between their connections at the periphery and the core. Collapse of a floor would collapse the entire structure due to the pancaking described above.
Main Entry: ap·pro·ba·tion
Pronunciation: "a-pr&-'bA-sh&n
Function: noun
Date: 14th century
a: an act of approving formally or officially
b : COMMENDATION, PRAISE