Recent geologic research has shown that earthquakes more destructive than formerly expected are likely to occur in the Pacific Northwest. To mitigate catastrophic loss, planners are gathering information to make decision on implementing regional seismic retrofit programs. This research develops a model to estimate regional earthquake losses for existing buildings, and determine optimal retrofit priorities and budgets. Fragility curves are developed to provide earthquake damage estimates for a range of seismic intensities. The published earthquake damage estimates of a large group of prominent earthquake engineering experts are extended to include the combined effect of structure type, earthquake-sensitive variations in building design, site-specific soil conditions, and local seismic design practice. Building inventory data from a rapid visual screening survey of individual buildings form the basis for modeling structural variations. Earthquake Hazard Maps are the basis of modeling the effect on building damage of ground motion amplification, soil liquefaction, and slope instability. Published retrofit effectiveness estimates and retrofit cost data are used to estimate post-retrofit damage avoided, lives saved, and retrofit cost. A Building Classification System is formulated to aggregate buildings with similar retrofit benefit magnitudes. A cost-benefit analysis is used as the basis for a retrofit prioritization and efficiency analysis, to establish the cut-off point for an optimal retrofit program. Results from an Expected Value and a Scenario Earthquake Event are compared. Regional Earthquake Loss and Retrofit Analysis Program (REAL-RAP) software was developed, and used to make a loss estimate for more than 7,500 buildings inventoried in the 1993 Portland Seismic Hazards Survey. One hundred percent of the loss of life is attributed to only 10-percent of the buildings. A retrofit analysis is made for a Design Basis Earthquake. Twelve-percent of the building inventory was identified for the optimal retrofit program, wherein 98-percent of the loss of life is avoided at less than one-quarter the cost of retrofitting all the buildings. An alternate optimal retrofit program was determined using an Expected Value Analysis. Most of the buildings in the Design Basis Earthquake optimal retrofit program are also contained in the alternate program.
| Identifer | oai:union.ndltd.org:pdx.edu/oai:pdxscholar.library.pdx.edu:open_access_etds-2238 |
| Date | 01 January 1996 |
| Creators | McCormack, Thomas C. |
| Publisher | PDXScholar |
| Source Sets | Portland State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Dissertations and Theses |
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