Utilizing Base-isolation Systems to Increase Earthquake Resiliency of Healthcare and School Buildings

In the recent large earthquakes in Chile, New Zealand, and Japan, a great number of critical facilities, including hospitals, schools, bridges, factories, airports, and utility systems, experienced extensive damage resulting in their loss of their function, and consequently substantial economic losses. Heavily affected communities were paralyzed for months following these large seismic events. The recovery process is estimated to last from several years to few decades. As a result, increased attention is being placed on strategies to design facilities that are both safe and damage resistant. It is often presumed that such an approach increases costs to an unacceptable level. The study reported herein compares the repair costs and repair times considering two designs for a typical three-story steel building: conventional fixed-base and damage resistant base-isolated moment resisting frame system. Performance-based earthquake evaluation tools are used to estimate repair costs and times for five different hazard levels considering two occupancy types critical for recovery: healthcare and school. The buildings are located in a seismic region in western North America. It is shown that using seismic isolation to enhance damage resistance results in significantly smaller repair cost, repair time, and improved resilience for the base-isolated alternative compared to a conventional fixed-base design.