[math-fun] another slight design flaw... skyscraper cooks cars
This makes me think of the notorious Hancock Tower in Boston. It was being built in the early 1970s, and had many problem (see below for an excerpt from Wikipedia). I was teaching one of my classes in a building only a block from it when it was a 70 story building clad in black painted plywood. Boy was it ugly. What was even worse, and what Wikipedia doesn't mention, is that when the new glass was installed, it was much more reflective than the old glass, and for a few months of the year it would blind all of the morning commuters driving in on Storrow Drive. Victor Inventing a way to use the blue reflective glass<http://en.wikipedia.org/wiki/Reflective_glass>in a steel tower came at a high price. Entire 4' × 11', 500-lb (1.2 × 3.4 m, 227 kg) windowpanes detached from the building and crashed to the sidewalk hundreds of feet below. Police had to close off surrounding streets whenever winds reached 45 mph (72 km/h). According to the *The Boston Globe <http://en.wikipedia.org/wiki/The_Boston_Globe>*, a scale model of the entire Back Bay was built in MIT<http://en.wikipedia.org/wiki/MIT>'s Wright Brothers wind tunnel <http://en.wikipedia.org/wiki/Wind_tunnel> to identify the problem. The research raised questions about the structural integrity of the entire building (due to unanticipated twisting of the structure), but it did not account for the loss of the glass panels. An independent laboratory eventually confirmed that the failure of the glass was due to oscillations and repeated thermal stresses<http://en.wikipedia.org/wiki/Thermal_stress>caused by the expansion and contraction of the air between the inner and outer glass panels which formed each window; the resilient bonding between the inner glass, reflective material, and outer glass was so stiff that it was transmitting the force to the outer glass (instead of absorbing it), thus causing the glass to fail.[5]<http://en.wikipedia.org/wiki/John_Hancock_Tower#cite_note-levy-5> In October 1973, I.M. Pei & Partners announced that all 10,344 window panes would each be replaced by a single pane, heat-treated panel at a total cost between $5 million and $7 million.[5]<http://en.wikipedia.org/wiki/John_Hancock_Tower#cite_note-levy-5>Approximately 5,000 of the original glass panes were removed intact, and were later reused by artists <http://en.wikipedia.org/wiki/Glass_art>.[6]<http://en.wikipedia.org/wiki/John_Hancock_Tower#cite_note-NYT1988-6> During the many months it took to diagnose and repair the building, sheets of plywood <http://en.wikipedia.org/wiki/Plywood> replaced many of the missing glass windows of the building, earning it the nicknames *Plywood Palace* and *Plywood Ranch* (the same name as a local lumber yard<http://en.wikipedia.org/wiki/Lumber_yard>chain at the time). The joke was that the Hancock Tower was *the world's tallest plywood building*. The building's upper-floor occupants suffered from motion sickness<http://en.wikipedia.org/wiki/Motion_sickness>when the building swayed in the wind. To stabilize the movement, contractors installed a tuned mass damper<http://en.wikipedia.org/wiki/Tuned_mass_damper>on the 58th floor. [7] <http://en.wikipedia.org/wiki/John_Hancock_Tower#cite_note-campbell-7>As described by Robert Campbell, architecture critic for *The Boston Globe*: Two 300-ton weights sit at opposite ends of the 58th floor of the Hancock. Each weight is a box of steel, filled with lead, 17 ft (5.2 m) square by 3 ft (0.91 m) high. Each weight rests on a steel plate. The plate is covered with lubricant so the weight is free to slide. But the weight is attached to the steel frame of the building by means of springs and shock absorbers. When the Hancock sways, the weight tends to remain still, allowing the floor to slide underneath it. Then, as the springs and shocks take hold, they begin to tug the building back. The effect is like that of a gyroscope, stabilizing the tower. The reason there are two weights, instead of one, is so they can tug in opposite directions when the building twists. The cost of the damper was $3 million. The dampers are free to move a few feet relative to the floor. According to Campbell, engineers discovered that—despite the mass damper—the building could have fallen over under a certain kind of wind loading. The structure was assessed as more unstable on its narrow sides than on the big flat sides. Some 1,500 tons of diagonal steel bracing, costing $5 million, were added to prevent such an event.[7]<http://en.wikipedia.org/wiki/John_Hancock_Tower#cite_note-campbell-7> On Tue, Sep 3, 2013 at 1:31 PM, Warren D Smith <warren.wds@gmail.com> wrote:
http://www.bbc.co.uk/news/magazine-23944679
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Warren D Smith