Part 5: Further Evidence of the Danger
LeMessurier now believed there might be serious danger. He turned to Alan Davenport, a Canadian consultant during the building's design. Davenport, who had run the original wind tunnel tests, now ran the tests again, using new calculations to reflect quartering winds and the change from welds to bolts.
The results, when compared with the building's original testing, confirmed LeMessurier's suspicions about increased stress in some of the building's structural members. His concern grew, since the results indicated that a 40 percent theoretical increase in a member's structural stress would be much greater under real-world conditions. During a storm, the whole building could shake, causing the structural members to all vibrate synchronously.
LeMessurier worked through the revised wind tunnel data, and quickly discovered that the entire building was vulnerable to a total structural failure -- if a storm pulled a joint apart on the 30th floor, the whole building would collapse. A "sixteen-year storm," that is, a storm occurring once every sixteen years, would have the strength to cause total structural failure. Though the electric tuned-mass damper had an enormous steadying effect on the building, and might help to reduce the stress on that joint, a strong storm would knock out the electricity necessary for running the damper.
Solving the problem was not difficult from an engineering perspective; heavy steel welded "Band-Aids" over the joints would give the building more strength than it was even originally designed to have. But it was the last day of July, and in order to complete repairs before the start of hurricane season, LeMessurier would have to announce the building's vulnerability and take responsibility upon himself. Doing so could cost LeMessurier his career and reputation as a structural engineer. He did not know how his news would be received by Citibank leadership, city officials, or the general public.