 Subsequently , the National Institute of Standards and Technology ( NIST ) was authorized to lead an investigation into the structural failure and collapse of the World Trade Center Twin Towers and 7 World Trade Center . The investigation , led by Dr S. Shyam Sunder , drew upon in @-@ house technical expertise as well as the knowledge of several outside private institutions , including the Structural Engineering Institute of the American Society of Civil Engineers ( SEI / ASCE ) ; the Society of Fire Protection Engineers ( SFPE ) ; the National Fire Protection Association ( NFPA ) ; the American Institute of Steel Construction ( AISC ) ; the Council on Tall Buildings and Urban Habitat ( CTBUH ) ; and the Structural Engineers Association of New York ( SEAoNY ) . 
