Buildings :: essays research papers

to hold the concrete foundation above in place. The nextobstacle in erecting a superskyscraper, and perchance the biggestone, is top. lofty buildings actually sway in the breeze, in much thesame way that a diving board bends under the weight of a diver.Building an edifice that doesnt topple over in the wind is easyenough. The real challenge is keeping the structure so stiff that itdoesnt swing withal far, cracking partitions, shattering windows andmaking the upper occupants seasick. As a rule, the top ofskyscraper should never drift more than 1/400 of its height at awind velocity of 150 km/h. Older buildings, like the Empire StateBuilding, were built so that their core withstood all bendingstresses. But geomorphologic engineers have since found that by shiftingthe bracing and support to the perimeter of a building, it can betterresist high winds. The most advanced buildings ar constructed likea hollow tube, with thin, outer columns spaced tightly together andwelded to broad hor izontal beams. Torontos First Canadian Placeand New Yorks World raft Center towers are all giant, framedtubes. A superskyscraper would undoubtedly need extra rigidity,which you could add by bracing its framework with giant diagonalbeams. Youll resonate this at Chicagos John Hancock Center wherethe architect has incorporated diagonal braces right into the look ofthe building, exposing five huge Xs on each billet to public view.Alternatively, you might design your building like a broadcastingtower, and tie it to the ground with heavy, sloping guy wiresextending from the four corners of the roof to the ground. A domination mechanism at the end of each cable would act like a fishingreel, drawing in the cable whenever the sway of the buildingcaused it to slacken. Tall buildings also encounter the problem ofvortex shedding, a phenomenon that occurs as the wind swirlsaround the front corners of the building, forming a series of eddiesor vortices. At certain wind speeds, these vortices v ibrate thebuilding, threatening to shake it apart. In New York Citys CiticorpCenter, engineers have tackled vortex shedding with a 400-tonneconcrete block that slides around in a finicky room on one of the