Systems of unattached, or freestanding, structures are highly vulnerable to damage and/or collapse during an earthquake, as evidenced during numerous past earthquakes including the 2014 South Napa Earthquake. This class of structural system includes historic multi-drum columns, radiation shields, unreinforced masonry walls, mechanical and electrical equipment, and most notably the large statue-pedestal system. During seismic excitation, these systems tend to respond in rocking and sliding modes with a high potential for overturning or collapse.
In an effort to understand the response of these systems and develop predictive models, CHEI researchers have conducted over 400 individual shake table tests. The experimental specimen consisted of geometrically-variable tower and pedestals, which could replicate the geometry of over 85% of culturally significant statues surveyed by the team in 2011 in Florence, Italy. The test sequence included variations of the height of the center of mass, the level of asymmetry, the interface (marble or smooth steel), and the type of earthquake motion. Numerical models, developed in MATLAB and LS-DYNA, were validated using the results of the extensive shake table testing campaign for the ultimate goal of predicting the response of large statue-pedestal systems.