Building Collapse at 2000 Commonwealth Ave – 40 Years Ago

The building failure and collapse of 2000 Commonwealth Avenue in Boston took place with barely a warning on the morning of January 25, 1971.  Long ago forgotten by many engineers of the day and unknown to many younger members of the structural engineering profession this disaster remains a classic example of what can go wrong in the design and construction of a building along with the resulting consequences.  Four construction workers lost their lives and 30 others were injured when a large portion of the 16-story reinforced concrete flat slab building collapsed.

Although the physical trigger mechanism was a punching shear failure on the upper floor, the overall collapse happened over a period of 10 – 20 minutes.  Collapse was a three stage event which included the collapse of the east roof slab after the punching shear failure and eventually the entire east side of the structure in progressive collapse fashion.  

Investigations of the collapse were executed by a number of organizations including a Mayor’s Commission and the well known engineering firm of Simpson Guppertz Heger (SGH) of Boston. (See SGH Post Collapse Photo).

As with many catastrophic collapses, there were multiple causes for the collapse as well as a number of contributing issues.  The primary causes were:

  • Inadequate placement of shores
  •  low strength concrete, possibly as low as 700 psi in some areas, which was due to inadequate cold weather operations (most likely resulting in frozen concrete).
  • construction overload of the roof

 In the end it also came to light that this project’s underlying  failings centered around procedural issues including inadequate construction supervision and quality control, confusion over various design and construction responsibilities, concrete mix and placement issues including cold-weather concrete placement errors and incorrect placement of some reinforcing.  All of these issues are of the type that could easily have been avoided, thus preventing the collapse in the first place. 

New 2000 Commonwealth Viewed in June 2011. Photo Credit: mkev

In summary,  the collapse of 2000 Commonwealth  exhibits at least two trends that  are frequently present in other failure case studies.  The first is that it often takes multiple problems to push a sturucture all the way to collapse.  Second is that out of that multiple set of problems,  procedural issues  (human error) is often one of the contributing factors. 

A detailed case study of 2000 Commonwealth, including a list of a number of excellent references on the topic, can be found on the Failures Wiki.   Also available on the wiki site is an extensive collection of other building case studies of interest including an installment on Concrete System Collapses and Failures During Construction.  Failures Wiki was created as an educational / industry resource and failures dissemination tool.  More information about the operation and participation in the site in the form of case studies or peer reviews are outlined on the wiki.

Acknowledgement:  Special thanks to Glenn Bell of Simpson Gumpertz Heger (SGH) for providing confirmation of the causes of collapse which are also being used to assist in the peer review of the Failures Wiki installment.

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