A study on the collapse control design method for high-rise steel buildings

Two direct causes led to the collapse of the World Trade Center (WTC) on September 11, 2001: column damage caused by aircraft crash, and the resulting large-scale fires. In spite of this damage, the towers remained standing after the crashes for 102 and 56 minutes, respectively, during which many lives were saved. The collapse of the WTC, however, may be taken as an alert that local failures can trigger a progressive collapse. It was also a landmark event since it alerted construction engineers about the importance of preventing progressive collapse in similar structures. Prevention of progressive collapse requires the development of design technologies for frames that have high redundancy. This paper presents a new collapse control design method for high-rise steel building structures. The basic concept of the present collapse control design method is to save human lives. It proposes how to assess and improve the redundancy of structures by assuming the loss of structural members due to hazards.