Rapid Assessment of Fragilities for Collections of Buildings and Geostructures

This report describes the results of research to develop a way to rapidly assess the fragility of structures and geostructures over a specified region. Structural performance under future earthquakes cannot be predicted with certainty. This is primarily due to the fact that an earthquake is a random phenomenon in nature, but another source of uncertainty comes from the structures themselves. For an individual structure or geostructure, the uncertainty arises largely from material properties and construction methods, but for a collection of structures whose individual characteristics are not known, additional uncertainty arises from macro-level parameters such as structural type, base planform, orientation, as well as vertical and planform irregularities, and the applicable design codes. Since detailed analysis of each structure or geostructure in the collection is impractical, this report addresses the problem by developing a methodology based on the use of computationally efficient metamodels to represent the overall structural behavior of the collection. In particular, response surface metamodels are developed using a Design of Experiments approach to select the most influential parameters. Monte Carlo simulation is carried out using probability distributions for the parameters that are characteristic of the target collection of structures or geostructures, and the fragility of the collection is estimated from the computed responses.National Science Foundation EEC-9701785published or submitted for publicatio