A suggested cause of the fire-induced collapse of the World Trade Towers

• Published in: Fire safety journal Vol. 37; no. 7; pp. 707 - 716
• Main Authors: Quintiere, J.G, di Marzo, M, Becker, R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2002; Elsevier Science
• Subjects: Applied sciences; Building technical equipments; Buildings; Buildings. Public works; Exact sciences and technology; Fire protection; High rise building; Miscellaneous; Stresses. Safety; Structural analysis. Stresses; Types of buildings; New York; United States; North America; America; Collapse; Terrorism; Mechanism analysis; Frame construction; Temperature effect; Young modulus; Fire; Ventilation; Tower (building); Buckling; Computing method; High rise building; Heat transfer; Structural analysis
• ISSN: 0379-7112
• DOI: 10.1016/S0379-7112(02)00034-6

An analysis is presented that calculates the temperature of the steel truss rods in the World Trade Center towers subject to a fire based on the building ventilation factor. The CIB correlation is used for the fire. Conduction analyses are made taking into account variable properties for the steel and the insulation. A structural failure model is described based on compression buckling of the truss rods due to a reduction in the Young's modulus. The computed times for the estimated failure or incipient collapse of the floors in both towers has been computed as 105±20 min for WTC 1 (north) and 51±9 min for WTC 2 (south), compared to the collapse times from the aircraft impact of 104 and 56 min, respectively. The insulation thickness and the difference of 19.1 mm ( 3 4 ″ ) and 38.1 mm ( 1 1 2 ″ ) between the two towers appear to have been the root cause of the collapses.