The loading condition for the Floor 12 and 13 assembly was calculated by imposing axial forces acting on the top of Floor 13. The column number sequence is shown in Figure 2.24 (NIST, 2008, NCSTAR 1A). The axial force acting on each column is given in Table 2.1. The loading for Column 79 is highlighted in the table because NIST concluded that the collapse of Column 79 at Floor 13 initiated the buildingâs progressive collapse (NIST, 2008, NCSTAR 1A).
Figure 2.24 Column number layout of Floor 13 (NIST, 2008, NCSTAR 1A).
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