John Hancock Building Boston, USA Facts 60 storeys Beautiful blue glass Windows Tallest building in New England Finished in 1976 AIA National Honour Award 1977 Plagued with flaws Foundations Over Budget $75M to $175 M Sway on upper floors Possibility of toppling Faulty glass windows Foundation problems Temporary steel retaining walls erected to create a void on which the building was to be built. Walls warped and failed. Damage to nearby buildings and utility lines. Faulty Glass Windows 1.2m x 3.4m 227kg Crashing from 240m down to sidewalk Police closed streets during high winds Why and How After much analysis, it was found that a thin lead-tape spacer that was placed between the double glazed windows had been the main problem. This spacer was soldered to the glass which had a reflective layer. The solder bonded very well with this layer and restricted movement within the glass. As a result, the glazing failed. Sway and Toppling Upper floor occupants suffered motion sickness. Solution to stabilize movement: a tuned mass damper on the 58th floor. Despite this damper, it was discovered that the building still could have toppled under certain wind loading! 1,500 tons of diagonal steel bracing added Problem Fixing Costs Between $5 million and $7 million for glass pane replacement. Damper, $3 million. Added Bracing, $5 million Numerous other costs including foundations etc… Lessons to be learnt More research required on building’s windows and facade. Sway and wind effects of vital importance. Must have an understanding of Structural behaviour!