The seismic protection of cultural heritage, particularly statues, is a critical issue due to its high cultural significance, difficulty to repair or replace artifacts, and observed poor behavior during past earthquakes. Recent research has explored analysis techniques and methodologies for predicting the seismic response of statues; however, these studies typically assume the statue to be either freestanding or rigidly attached. The seismic response of statues with these different boundary conditions varies widely and therefore accurate characterization is critical.
CHEI researchers conducted a case study of seismic mitigation for statues at the Asian Art Museum in San Francisco, CA. The statues of interest, the Colossi, were large (over 2.0 m in height), solid sandstone artifacts from the Kingdom of Saudi Arabia dating to the 4th-3rd century BCE. Three-dimensional digital reconstructions were generated using LiDAR data, which serve as the base for detailed finite element analyses. Experimental modal analyses and system identification were also conducted. This technique measures the acceleration response at many points along the statue-pedestal system to understand the system’s dynamic characteristics.
Given the tall aspect ratios of the statues and the potential for damaging forces to develop during an earthquake, the statues were base isolated. This technique attempts to isolate the statue from the movement of the floor during an earthquake. The isolation system consisted of low-friction sliding plates which were tested at the UC San Diego Powell Laboratory shake table facility prior to installation. The results of these laboratory and field tests can guide the identification of vulnerable artifacts and the design of protective systems for irreplaceable heritage structures.