Abstract
At the September 11, 2001, New York World Trade Center Towers did not collapse immediately after the aircraft impacts, despite the localized damage. Thus, the reserve capacity to the phenomenon besides assumption was called "redundancy", and after the WTC two towers' collapse, when taking the safety of a building into consideration, it had been recognized to be important property. In order that a building structure could not collapse and be secure safety to the load beyond anticipation on its structural design like the impulsive load by a collision, explosion, etc., it is important the building structure possesses structural redundancy. The purpose of this study is to evaluate the overall damage and the local damage and its structural redundancy against the aircraft impact equivalent to that in WTC for the Japanese typical 50 story high-rise steel building.
