A PROCEDURE FOR ASSESSING THE FUNCTIONAL RELIABILITY OF HOSPITAL SYSTEMS

An effective reliability-based procedure is presented to assess the ca pability of hospitals to be functional after a seismic event of a give n intensity. Every major function in a hospital depends on the joint a ction of various cooperating services, which in turn are made up from a certain number of sub-services. Such a complex organization is descr ibed in terms of a logical scheme and subsequently reduced to a minima l cut-set representation. Fur each sub-service a collapse criterion is defined, by which the strength is compared to the action load, both r epresented as random variables. Strengths are evaluated through assess ment analyses based on design drawings. Loads are evaluated from 3-D l inear dynamic analyses under seismic input. This is given by the Euroc ode 8 elastic response spectrum, scaled at a given peak ground acceler ation and account for the position of the sub-service within the build ing. By calculating the failure probability of each service by FORM (F irst Order Reliability Method) or SORM (Second Order Reliability Metho ds), the probability of functional interruption is obtained in terms o f Ditlevsen bounds, conditional on a given earthquake intensity. The m ethod helps to single out weak elements and potential sources of damag e (structural, non-structural, equipment) within the hospital. This al lows: (a) to investigate quantitatively the effectiveness of different upgrading criteria, (b) to select rationally intervention hypotheses, both in the retrofitting and rehabilitation of existing hospitals and in the design optimization of new ones, and (c) to evaluate different investment options for seismic vulnerability mitigation. As an exampl e, an application to a case study hospital is presented. Copyright (C) 1996 Elsevier Science Ltd