2000 Commonwealth Avenue: January 5, 1971
This was a progressive collapse of a cast-in-place reinforced concrete flat-slab structure. Punching shear was determined to have been the triggering mechanism but the real problem was in the numerous errors and omissions by every party involved in the project (Delatte 133-143). The investigating committee determined that if the construction had had a proper building permit and had followed codes, then the failure could have been avoided (Delatte 142). Some of the problems leading to the collapse are:
1. Not following the structural engineers specifications for shoring and formwork
2. Lack of concrete design strength
3. Lack of shoring or removed too soon
4. Improper placement of reinforcement
5. Little construction control on site
6. Owner changed hands many times
7. Almost all jobs were sub contracted
8. No architectural or engineering inspection done
9. Inadequate inspection by the city of Boston
10. The general contractors representative was not a licensed builder
11. Construction was based on arrangements done by the subcontractors
12. No direct supervision of subcontractors
Sound familiar? For the Montgomery County, MD Silver Spring Transit Center, add:
13. Under-designed
14. Failed to provide expansion joints
15. Built slabs more than one inch thinner than specified
16. Failed to adequately inspect and test concrete before and during placement
17. Understrength concrete
18. Added water at the jobsite to the concrete mix
19. Failed to follow standard cold weather curing requirements
20. Missing reinforcement
21. Applied greater initial posttensioning forces than called for
22. Failed to address extensive concrete cracking in a timely manner
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