Seismic performance assessment of base isolated and conventional hospitals through fragility analysis

Abstract

After the 2010 Maule earthquake Chilean authorities require the implementation of base isolation systems in new public hospitals. However, in Chile the typical seismic force-resisting system of non-isolated hospitals is made up of reinforced concrete shear walls, whereas that of isolated buildings is made up of reinforced concrete frames. Since the former is much stiffer than the latter, there is a question on the effectiveness of base isolation in reducing the seismic demands on new hospitals with respect to that on conventional hospitals, particularly the interstory drift demand under low levels of ground shaking. This study evaluates the main results of a comparative analysis of the seismic performance of isolated and non-isolated hospitals considering the typical structural system in each case. Results are compared with empirical observations on the effects of earthquakes on the Chilean building inventory and the suitability of limit state thresholds defined in the literature is discussed.