Large-Scale Experimental Tests of Composite Steel Floor Systems Subjected to Column Loss Scenarios

As demonstrated by terrorist attacks against the Murrah Building in Oklahoma City and a U.S. Embassy building in Nairobi, Kenya, some structures may be vulnerable to progressive collapse. Previous computational studies have shown that floor systems play a key role in redistributing loads during progressive collapse events, but only a few experimental studies support these results. The aim of the current research is to experimentally characterize the behavior of steel-concrete composite floor slabs under column loss scenarios. Two large-scale tests on isolated sections of a steel-framed building were conducted until complete collapse. The two specimens were designed and detailed according to commonly used practices found in buildings in the United States. No special provisions to mitigate progressive collapse were included in the design. The first specimen was an interior 2-×2-bay section, and the second specimen was an exterior 2-×1-bay section. Both specimens were tested under a center column loss scenario. The column was statically removed while the floor slab was uniformly loaded under service load conditions. Because both specimens survived the column removal stage, the slab was subsequently loaded with a uniformly distributed load until total collapse was achieved. Observations from the test program indicate the potential for significant capacity of composite floor systems following column loss.