Behavior of Special Hospital Equipments as Rigid Block with Mass Eccentricity Subjected to Horizontal Component of Ground Motion

Abstract

The functionality of a hospital after major earthquakes is of great importance, and this functionality is highly dependent on the performance of the hospital’s equipments. Therefore, in seismic areas paying attention to the seismic behavior of equipments is necessity either for design or for evaluation purposes. Many of hospitals’ equipments can be modeled as rigid blocks. Rigid blocks with uniform mass distribution have been studied extensively so far. However, in case of hospitals’ equipment these blocks may have large mass eccentricity, which makes its seismic behavior more complicated. Ventilators in operation rooms are among these equipments. In this study the equipments was modeled as rigid block with mass eccentricity, subjected to horizontal components of a set of selected earthquakes, assuming the amount of friction high enough to prevent the block from sliding. Analyses were done using a computer program, developed by the authors, based on the fourth order Runge-Kutta-Nistrom technique in MATLAB environment. Results show the high sensitivity of block’s behavior to the amount of eccentricity and earthquake characteristics, so that by increase of only 1% in the peak ground acceleration (PGA) of the record the mode of behavior changes from rocking to overturning. Results also show that the criteria, being used currently for seismic evaluation of equipments, are not proper.