Talk in pairs. 1 Think of a few things you have that are well designed. How would you describe them? 2 Think of some things that you feel are badly designed. Explain why. Read the article about a design problem with potentially disastrous consequences. 1 Which field of design does this problem concern, technical or artistic? Why? 2 What is so spectacular about the supporting structure of the tower? b Reading 4 a The design flaw that almost wiped out a NYC skyscraper The Citicorp Center (later renamed the Citigroup Center, now known as 601 Lexington), built in 1977, was then, at 59 stories, the seventh-highest building in the world. You can pick it out on the New York City skyline by its 45-degree-angled top. But it’s the base of the building that really makes the tower so unique. The bottom nine of its 59 stories are stilts. This thing doesn’t look sturdy. But it has to be sturdy. Otherwise they wouldn’t have built it this way. Right? The architect of the Citicorp Center was Hugh Stubbins, but most of the credit for this building is given to its chief structural engineer, William LeMessurier. From the beginning, the Citicorp Center was an engineering challenge. When planning for the skyscraper began in the early 1970s, the north-west corner of the proposed building site was occupied by St Peter’s Lutheran Church. The church allowed Citicorp to demolish the old church and build the skyscraper under one condition: a new church would have to be built on the same corner, with no connection to the Citicorp building and no columns passing through it. Designs impacted on by building restrictions have to be spectacular by nature. LeMessurier said he got the idea for the design while sketching on a napkin at a Greek restaurant. And this is how the building works: ■■ Nine-story stilts suspend the building over St Peter’s church. But rather than putting the stilts in the corners, they had to be located at the midpoint of each side. This meant that the church could still be in the corner of the building plot and didn’t have to be rebuilt. ■■ Having stilts in the middle of each side made the building less stable, so LeMessurier designed a chevron bracing structure – rows of eight-story Vs that served as the building’s skeleton. ■■ The chevron bracing structure made the building exceptionally light for a skyscraper, so it would have swayed in the wind. LeMessurier added a tuned mass damper, a 400-ton device that keeps the building stable. It was an ingenious, cutting-edge design. And everything seemed just fine – until, as LeMessurier tells it, he got a phone call. In 1978 an undergraduate architecture student contacted LeMessurier with a bold claim about his building: that the Citicorp Center could blow over in the wind. The student was studying the Citicorp Center and had found that the building was particularly vulnerable to quartering winds (winds that strike the building on its corners). Normally buildings are strongest on their corners, and it’s the perpendicular winds (winds that strike the building at its faces) that cause the greatest strain. But this was not a normal building. 132 Language skills Extras Explore 10 From design to brands Nur zu Prüfzwecken – Eigentum des Verlags öbv
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