In May 1958 Concrete Construction covered a project that used the lift-slab method of raising floors, first introduced in 1950. Through the years we followed the progress of this method where all of the floor slabs are cast at ground level one atop the other, then raised as a group and dropped off one by one. In February 1986, lift slab was described as “a basic method of economic concrete construction, especially for structures characterized by repetitive framing from floor to floor.” But then, on April 23, 1987, as the slabs were being lifted during lifting of the slabs for construction of the L'Ambiance Plaza in Bridgeport, Conn., the structure collapsed, with the slabs pancaking to the ground, killing 28 workers and seriously injuring 16 more. Although the exact cause is still argued and despite the economy of lift slab, OSHA restrictions and general uncertainty led to virtual abandonment of the technique.

—Bill Palmer

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