John Hancock Building Boston, USA

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John Hancock Building Boston, USA
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Facts

• 60 storeys
• Beautiful blue glass Windows
• Tallest building in New England
• Finished in 1976
• AIA National Honour Award 1977

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Plagued with flaws

• Foundations
• Over Budget 75M to 175 M
• Sway on upper floors
• Possibility of toppling
• Faulty glass windows

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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.

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Faulty Glass Windows

• 1.2m x 3.4m
• 227kg
• Crashing from 240m down to sidewalk
• Police closed streets during high winds

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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.

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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

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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

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Lessons to be learnt

• More research required on buildings windows and
  facade.
• Sway and wind effects of vital importance.
• Must have an understanding of Structural
  behaviour!