Medical Equipment Seismic Performance Evaluation for Preventing Rocking and Overturning

• Published in: Transactions of Japanese Society for Medical and Biological Engineering Vol. 60; no. 6; pp. 139 - 148
• Main Authors: HITOMI, Mayu, KURATA, Masahiro, AIDA, Shinji, SHIMOTO, Manabu, CHO, Kosai, OHTSURU, Shigeru
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society for Medical and Biological Engineering 10.12.2022
• Subjects: dialysis; earthquake engineering; medical equipment; neonatal intensive care unit; shaking table test
• ISSN: 1347-443X; 1881-4379
• DOI: 10.11239/jsmbe.60.139

This research examined the seismic behavior of medical equipment, which supports advanced hospital functions through shaking table testing and numerical analysis, and derived evaluation index for mitigating damage. The shaking table test observed the rocking and overturning of neonatal beds and a dialysis liquid feeding apparatus under sine waves and the building floor responses during earthquakes. The rocking and overturning damage occurred only when the casters of equipment were all locked, and the ratio between the equipment’s gravity center height (h) and leg width (b), b/h, is smaller than a certain threshold. The influence of equipment dimensions and weight on the seismic behavior was studied by parametric analysis using a distinct element method (DEM) model of equipment. The probability of damage decreased significantly when the ratio between the b/h becomes large. For the floor velocity response of 80cm/s, which is assumed for the approximate return period of 500 years and with the response amplification factor (the ground to floor response ratio) of 1.6, the probability of overturning became negligible when the b/h is 0.4 or larger. This paper also presents an analytical equation to calculate sufficient safety weights added to existing equipment for conforming to the above thresholds of b/h.