Earthquake-induced damage assessment of critical medical equipment using experimentally validated rolling and sliding nonlinear models

Hospital functionality relies not only on the building's structural robustness but also on the seismic performance of its Nonstructural elements, Systems, and Contents (NSC). The objective of this study is to characterize the earthquake-induced damage to the medical equipment deployed in the full-scale, five-story concrete building tested at the University of California, San Diego (UCSD) in 2012 when subjected to Design (DE) and Maximum Considered Earthquake (MCE) levels of demand with Fixed-to-the-Base (FB) support condition. The experimental equipment displacement responses are extracted using the Camera Projection Technique (CPT). Then, sophisticated rolling and sliding models, including instantaneous motion tracking and impact detection are developed to reproduce the equipment behavior obtained from CPT. It was found that CPT was capable of extracting the observed responses and identifying impacts despite the severity of the shaking as long as no significant uplift of the equipment occurred. In addition, both numerical models were capable of reproducing the equipment's displacement trajectories, rotations about the vertical axis (yaw), and impacts as long as no interlocking of the equipment's parts occurred. Moreover, a case study of a partially equipped Emergency Room (ER) was set up to demonstrate that even for low-intensity motions, the damage to equipment may be significant. Finally, the impact acceleration (${\vec{a}}_{imp}$) is proposed as a proxy indicator of damage to medical equipment; however, more functionality tests accompanied by detailed pre- and post-inspections are needed to define robust damage limit states and performance objectives for medical equipment.