May 14, 2003
EAI recently completed a study of damage to a 41-story office building located on Liberty Street immediately south of the World Trade Center (WTC) site. The collapse of WTC Towers 1 and 2 produced significant collateral damage to the building, especially the North Face. As part of a study of such collateral effects EAI has developed a three-dimensional damage model of the building, taking into account damage due to falling debris as well as damage caused by the pressure wave produced by the collapsing towers impacting on the ground. Each of the more than 4,600 windows are included in the model, along with each of the 41 floors and 64 columns.
By means of the VEXDAM 6.0 software, two views of each face of the building have been generated; the first view being before the collapse and the second after collapse. The before- collapse view of the North Face is shown in Figure 1 while the after-collapse view is shown in Figure 2. As expected, the predicted damage to the North Face is quite extensive.
The before-collapse view of the East Face is shown in Figure 3 while the after-collapse view is shown in Figure 4. Predicted damage to the East Face is primarily limited to those windows nearest the North Face.
The before-collapse view of the South Face is shown in Figure 5 while the after-collapse view is shown in Figure 6. Predicted damage to the South Face is very slight and is limited to the first four floors.
The before-collapse view of the West Face is shown in Figure 7 while the after-collapse view is shown in Figure 8. Predicted damage to the West Face, as expected, is similar to, but somewhat greater than, that for the East Face.
The patterns of predicted damage are consistent with the actual damages
shown in Figures 9 through 12. In Figure 9,
the North Face is shown, while in Figure 10, the
South Face. The lower portion of the West Face is shown in Figure
11. Figure 12 shows a combination of
the North and West Faces.