John Hancock Building
Façade Failure
Group 8
Design
Architect – Henry Cobb of I.M Pei, Boston
 1.7 acre site in Copley Sq Boston
 60 stories high
 Reflective blue tinted glass
 Pin strip geometry

Construction

1968 - 1976
 Glazed curtain walls (hold no floor loading)
Failure!

During contruction
 20th Janurary 1972
 75 mph gusts
 65,500 lb glass panels shattered
Solution

10,344 panels were replaced with single
pane panels

Costing the window company $7 million
Why?

The building did vibrate but this was not the
main cause.

Failure was due to the double paned
windows that failed due to a design defect.
It was still thought the building
might fall?

Vibration was solved by adding a
“tuned mass damper”

Prevention of the building tipping during stiff
wind
$5 million reinforcement was added consisting
of 1,500 tonnes of steel bracing ,these were placed
along the walls at the core of the building.
How did such a big mistake
happen?

It was discovered that the developers had
opted for less expensive aeronautical tests
which didn’t stimulate gusty winds.
Lesson

Engineers when looking at the wind effects
of a building should also look at the
envelope.

Cost cutting could be crucial.