World Trade Center 5

The World Trade Center Building 5 (WTC 5) was a 9 story office building located on the northeast corner of the World Trade Center Plaza. The collapse of WTC 1 caused damage to WTC 5 and started fires in it (McAllister 2002). The uncontrolled fires resulted in complete burnout of most floors and partial collapse of four floors. The building was steel frame construction with field-bolted connections between floor beams and column tree assemblies. Failure of large sections of floor, in areas not damaged by falling debris from WTC 1, resulted from bolt tear-out at these connections as a result of the uncontrolled fires (Figure 8–14). Photographs of two recovered samples of floor beams (Figure 8–15) show how the field bolts tore out from the beam web weakened by the fires (McAllister 2002).
338 NIST NCSTAR 1-9, WTC Investigation