12.07.2015 Views

Report - PEER - University of California, Berkeley

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a. building elevationb. plan viewFigure 3. MCEER demonstration hospital.Protection <strong>of</strong> structural framing systems against gross damage during severeearthquake shaking motivated the initial development (in the 1970s and 80s) andimplementation (1980s) <strong>of</strong> seismic protective systems: seismic isolation bearings andsupplemental passive damping devices. Hospital buildings were early candidates forthe use <strong>of</strong> protective systems because <strong>of</strong> the need to maintain hospital function after amajor earthquake: essentially eliminating damage to the structural framing.Nowadays, seismically isolated buildings are designed to restrict substantial (or all)inelastic action to the isolators in maximum capable earthquake shaking. Buildingsincorporating supplemental dampers are designed typically to restrict substantialinelastic action (damage) to the damping devices in design and maximum earthquakeshaking and thus to eliminate damage to components <strong>of</strong> the gravity-load-resistingsystem.Fifteen mathematical models representing different traditional and protectedlateral-force-resisting systems were developed in the OpenSees s<strong>of</strong>tware environment(http://opensees.berkeley.edu/) for analysis and evaluation. The 15 models aresummarized in Table 1; the baseline model was M3. The traditional framing systemsare M3 and M6: moment-resisting frames. Buckling restrained braces (BRBs),displacement-dependent dampers, were implemented in M7. Fluid viscous dampers(FVDs), velocity-dependent dampers, were implemented in M8 and M9. Models M10through M13 include linear viscoelastic seismic isolation bearings: one mathematicalmodel used for low- and high-damping rubber bearings. Models M14 and M15include bilinear seismic isolation bearings: the mathematical model used typically forlead-rubber and Friction Pendulum bearings. Much additional information will beavailable in Astrella (2004).116

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