The Oregon Resilience Plan – Critical and Essential Buildings – February 2013 73 <br /> <br /> <br />4. Critical and Essential Buildings <br />Introduction <br />Building safety and functionality will be critical both during and after a magnitude 9.0 Cascadia <br />subduction zone seismic event. Oregon’s buildings must be able to withstand the intense ground <br />shaking without devastating loss of life, damage to infrastructure, or significant disruption to our <br />communities and economy. Because of this, the Critical Buildings Task Group was assigned the task of <br />reviewing the status of buildings in critical sectors and considering how they may be affected by a <br />Cascadia subduction zone event. Buildings in these critical sectors include those that are necessary for <br />the immediate response to the event—such as emergency operations centers, hospitals, police and fire <br />stations, and emergency shelters—and buildings that are necessary for the provision of basic services to <br />communities as they begin to restore functions and return to normal life—for example, schools, <br />housing, certain retail stores, and banks. The group reviewed one additional building category: <br />vulnerable buildings. These are unreinforced masonry and non-ductile concrete structures that have <br />shown time and again in past earthquakes that they pose a very significant and direct threat to life <br />safety. <br />While the task group acknowledges that there are many other buildings and sectors that could also be <br />considered vital to resilience, the group decided to limit the study to those buildings that we believe are <br />most critical to resilience in the case of an earthquake scenario. Buildings and structures that are directly <br />associated with and critical to the functionality of communications, utilities, ports, water supply, <br />wastewater, and fuel storage have been evaluated separately by other task groups; the assessments and <br />recommendations of these task groups are provided elsewhere in this report. <br />To assess the overall seismic resilience of critical and essential buildings in the state of Oregon, the work <br />group considered the gap between the building-performance goal needed for seismic resilience (target <br />state) and the expected seismic performance of the buildings as they are today (current state). Most of <br />the building sectors that are critical to the response to a seismic event are recognized by the current <br />building code. Oregon’s current seismic design standard for new buildings, the Oregon Structural <br />Specialty Code (OSSC), classifies buildings according to four distinct occupancy categories based on their <br />relative importance to life safety in the event of a natural disaster (see Figure 4.1). Occupancy <br />Categories III and IV are structures that have large assembly areas (such as schools), or that are deemed <br />essential to emergency response (such as hospitals, police and fire stations, and emergency operations <br />centers). Buildings that fall under these Category III or IV classifications were obvious components of the <br />Critical Buildings data set used in our evaluation. Under current code, occupancy category type III <br />buildings are designed for a 25-percent higher seismic load than Category I and II buildings. Category IV <br />buildings are designed for a 50-percent higher load.