Uncertainty modeling of earthquake hazards

The evaluation of the expected response of existing projects (i. e., buildings, lifelines, facilities, cities, regions, etc.) during an earthquake is difficult and complex. The interstory drift of a building and the response of the main structural system are examples of parameters typically used to make judgments. The behavior of a project clearly depends on structure, but it also depends on many other factors that often are not considered. These include safety culture, management, condition, use, construction, materials, and so on. The modeling and measurement of these factors vary in quality because they are very different in nature. A model is proposed that enables these factors to be put together to assess the proneness to failure of a particular project. Uncertainty is classified into fuzziness, incompleteness, and randomness. Hierarchically arranged holons describe the essential form of the project and capture inherent fuzziness. The model includes tests (such as audits) that a project must pass in order to be declared dependably safe. It is argued that the ingenuity of these tests is the best defense against incompleteness. Engineering and scientific models are included as appropriate. An interval probability is used to measure the available evidence about the dependability that a holon will be able to sustain its function during an earthquake.