The Effect of the Placement of Support Columns on the Structural Integrity of the World Trade Center

Overview

Objectives/Goals This expirement will acertain if the spread out placement of the support columns was a factor in the World Trade Center collapses Methods/Materials 150 5"x0.75"x0.125" pine strips; 10.1' of 0.25"x0.25" wood dowel; 48 twist ties; 1 box cutter; 1 hack saw; 2 5"x5"x0.5" wood squares; 1 hot glue gun; 1 pair of shears; 1 drill; 1 8" inch drill bit (diameter doesn't matter); 1 0.31" drill bit; 1 ruler ; 1 stress anaylzer. To summarize the procedures, two, 18" high, model towers were constructed out of the materials above. One tower, representing a twin tower, will have its support columns near the perimenter while the second tower will have it columns equidistant from the center and the corner. Both towers were placed into a stress analyzer which applied a compresion force from the top. Results The first tower, which represents the World Trade Center, was able to hold 662 pounds of force with 0.235 inches of displacement, while the second tower with the normal column placement was able to hold 894 pounds of force at 0.355 inches of displacement. Conclusions/Discussion When placed in the stress analyzer, The first tower, which represents the World Trade Center, was able to hold 662 pounds of force with 0.235 inches of displacement, while the second tower with the normal column placement was able to hold 894 pounds of force at 0.355 inches of displacement. The results are do to a difference of force vectors, which are the measure of a forces magnitude and force. During the stress test, the Newtons exerted on the towers, create two resultant vectors acting against each other. Each resultant vector consists od two, non-colinear, forces applied at one point, which, in this case, represents the support column. The first vector is the result of the two wood planks pushing against the column to secure it in place. The second resultant vector is the force of the two perimeter walls acting against the aforementioned wooden planks. The normal tower was able to carry more weight because the first and second vector were near equilibrium. For the spread-out design, the second vector is much small than in the normal tower as a result of the columns shorter distance from the wall. Since the first vector is disproportionally larger than the second vector, it means that there is more force pushing the column towards the corner than is pushing the column towards the center, causing quicker structural failure.

Competition history

• CSEF 2009 Applied Mechanics & Structures · Entry S0224

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