CASE STUDY JOHN HANCOCK TOWER The John Hancock Tower is a 62-storey, 240m high skyscraper in the Back Bay neighborhood of Boston. Designed by Henry Cobb, it was known in the 1970s for its architectural achievement as well as for its engineering flaws. The building met initial opposition due to the fact that it would cast a shadow on Trinity Church, a historic church nearby. During the excavation for the foundation, temporary steel walls became deformed, so clay and mud John Hancock Tower Boston and Trinity Church 8 damaged utility lines, the pavement and nearby buildings. But the real trouble started once the building was under construction. Big window panes detached from the building and Henry Cobb crashed to the sidewalk hundreds of feet below. A scale model of the entire Back Bay and an aeroelastic model of the John Hancock Tower were built and tested in the wind tunnel to identify the problem. The research raised questions about the structural integrity of the entire building, but did not explain 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 caused by the expansion and contraction of the air between the inner and outer glass panes which formed each window. Numerous steel braces were installed to ensure its structural integrity. In addition, a tuned mass damper had to be installed when it was discovered that the building was oscillating too much causing motion sickness in the upper floors occupants. Through this case study, the opportunity and responsibility of the civil engineer to actively participate in the architectural evolution of a building is demonstrated. Read the passage and answer the questions below. 1. Where is the tower located? 2. Why was there opposition to its construction? 3. What was the problem with the windows? 4. What was done to try and solve the problem? 5. What were the conclusions of the research? 6. What was the problem with the upper floors? 7. How was it solved? 8. What does this case study demonstrate? achievement: risultato brace: putrella to cast a shadow: gettare un ombra eventually: alla fine failure: cedimento flaw: difetto pavement: marciapiede tuned mass damper: smorzatore a massa accordata (fornisce stabilità in caso di forte vento o di un evento sismico) utility lines: linee di servizio (elettriche, telefoniche, etc.) window pane: vetro della finestra HISTORY OF ARCHITECTURE 333