- Author
-
Lew, H. S.
|
Carino, N. J.
|
Fattal, S. G.
|
Batts, M. E.
- Title
- Investigation of Construction Failure of Harbour Cay Condominium in Cocoa Beach, Florida.
- Coporate
- National Bureau of Standards, Washington, DC
- Sponsor
- Department of Labor, Washington, DC
- Report
-
NBSIR 81-2374,
September 1981,
- Distribution
- Available from National Technical Information Service
- Keywords
-
residential buildings; collapse; accident investigations; concrete construction; shear properties; shear tests; concrete slabs; failure; florida
|
shear stress
|
shear strength
|
concrete slabs
- Identifiers
- harbour cay condominium; cocoa beach (florida); progressive collapse
- Abstract
- The investigation of the collapse of a five-story reinforced concrete flat-plate structure under construction at Cocoa Beach, Florida is presented in this report. The investigation included onsite inspection, laboratory tests and analytical studies. Based on the results of this investigation, it is concluded that the most probable cause of the failure was insufficient punching shear capacity in the fifth-floor slab to resist the applied construction loads. Two factors contributed to the low punching shear capacity: one in the design and the other in the construction of the building. In the design, the omission of a check for punching shear resulted in a smaller slab thickness than needed to satisfy the Code requirements. In construction, the use of specified chairs having insufficient height to support the top reinforcing steel resulted in more than the cover specified in the structural drawings. Both factors contributed to reducing the effective depth of the slab such that it had insufficient strength to resist the construction loads. The analysis showed that shear stresses in the slab at many column locations on the fifth floor exceeded the nominal shear strength. Thus, punching shear failure at one of the columns precipitated a progressive failure of the slab throughout the entire fifth floor. Collapse of the fifth floor, in turn, caused the successive collapse of the lower floor slabs. The failure of the fifth floor slab most likely initiated at column G-2, an interior column which supported the last bay of freshly placed roof concrete prior to the collapse.