Resolution No. 4814 - Laserfiche WebLink

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earthquakes. Similarly, new buildings will be built in accordance with current Seismic Zone 3 requirements and thus the seismic capacity of the building stock in the Eugene/Springfield Metro Area will gradually improve over time as the existing stock is gradually replaced and/or upgraded. However, for some types of buildings which are more vulnerable or more important than typical buildings, seismic retrofit may be highly desirable. Prime candidates for possible seismic retrofits include: any buildings that are substantially more vulnerable than typica~ buildings (e.g., unreinforced masonry buildings), · buildings on soft soil sites, and - essential service facilities such as major medical facilities, police and fire stations, schools, and emergency shelters. Specific buildings may be substantially more vulnerable than typical buildings because of their structural system. Examples of vulnerable building types include: unreinforced masonry, precast concrete frame, concrete or steel frame with unreinforced masonry infill walls, concrete moment resisting frame, and precast concrete tiltup walls. Buildings may also be substantially more vulnerable than typical buildings because of their design characteristics. Examples include buildings with soft first stories (taller than other stories and/or with large expanses of windows without shear walls) and buildings with major configurational irregularities, as well as wood frame buildings with cripple wall foundations or with sill plates not bolted to the foundation. Thus, we suggest that Level Three risk assessments focus primarily on such buildings, especially for essential service facilities. A Level Three assessment provides a building-specific evaluation, more accurate than generic assessments based on typical buildings. Ideally, a Level Three assessment would include a site specific seismic hazard analysis, taking into account soil conditions, and a building-specific evaluation of the seismic vulnerability of each building under evaluation. In addition to buildings, there are other critical facilities which may be vulnerable to seismic damage, including utility and transportation system infrastructure. Minimizing earthquake damage to such facilities is particularly important to a community because loss of function of critical utility or transportation system infrastructure may have a very large economic impact on the community. Facilities that should have a high priority for Level Three Risk Assessments include: electric power substations (especially high voltage substations), water and waste-water treatment plants, water reservoirs, bulk fuel storage tanks and hazmat storage tanks, dams and bridges. For utilities in general, non-structural mitigation measures are often very cost-effective and should have a high priority. For buildings, utilities and other important facilities, the seven-step Mitigation Planning methodology outlined in Chapter I is appropriate. For prioritizing between mitigation projects, the principles of benefit-cost analysis apply to mitigation projects for all hazards, including seismic hazard mitigation. FEMA has software available to conduct such analyses of prospective earthquake hazard mitigation projects. See also the example seismic mitigation project in the Appendix. 10-15