On the design aspects the teams identified that the slabs were slim compared to the standards offered by ACI. The used slab had 8 inches whereas the minimum requirement is set at 11 inches. The process of punching shear was overlooked when designing the slabs. The structural engineer, who retired from NASA, also failed to make the necessary calculations on concrete requirements such as beam shear and column reinforcement spacing.
Harbour Cay Condominium was designed to be a medium sized building with a total height of 242 fees and 58 feet in width. The preassembled plywood was made from flying form where they constructed the floor slabs, 8 inches thick. The east side of the building hosted a detached elevator tower whereas the north and south ends were occupied by the stairwells. The building had both exterior and interior columns that measured 10 x 12 and 10 x 18 inches respectively. The structural engineer advocated for above-grade concrete to be used, with strengths of up to 4,000 psi. 11 There were pile caps supporting exterior slabs. Floor slabs were placed twice per week with the first session covering half the total space. The roof plan indicated it would be cast in one day.
Harbour Cay Condominium was near completion when it collapsed. The concrete was already placed on the flying forms of the roof when things changed. The construction workers were pouring concrete on the roof slab when a loud crack was heard and it all fell like a house of cards. Witnesses reported that the fifth floor fall first. The upper floor fell on the lower ones leading to comprehensive total building collapse (Lew, Center for Building Technology, & United States, 1982). There reports indication that the workers had reported presence of web like cracks on the slabs with increased deflection of about 2 inches. The structural engineer was summoned to address the situation, but he insisted that it was not a big dal considering the progress made.