I like your reasoning, but I wonder about magnitudes. Since: 10 feet/story * sin(0.001 degree) = .00017 feet/story then: 50 stories * .00017 feet/story

I like your reasoning, but I wonder about magnitudes. Since: 10 feet/story * sin(0.001 degree) = .00017 feet/story then: 50 stories * .00017 feet/story = .0085 feet [building] If things added up this way, your magnitudes would be way off. In fact, since sin(x) is linear for small x, you'd need about 100x more angle to get 100x more deflection. 100x more deflection would be about 0.85 feet one way, or 1.70 feet peak-to-peak. Two feet peak-to-peak for 50 stories matches some of the figures quoted in the article for buildings of this scale ("A hundred-story building, by comparison, may move on the order of two-and-a-half to three feet to each side..."). However, on reflection, I think the offsets cumulate quadratically. Because: * \ \ [story 2] \ | | [story 1] | The first story has an angular offset, but the angular offset of the second story adds to that of the first, etc. This must be common knowledge among structural engineers. In that case, since we can just add all the displacements, the appropriate quadratic multiplier would be 50 * 49/2 = 1225, not just 50, and the total displacement is: 1225 * .00017 feet/story = 0.21 feet. This would mean your original, very tiny, angles were only about 5x too low. Nice work!