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Developing Fragility Curves
by Ardalan Sabamehr, Ph.D.

The type and extent of damage that a component will experience is uncertain. Component fragility functions are statistical distributions that indicate the conditional probability of incurring damage at a given value of demand. Fragility functions are assumed to be lognormal distributions. A unique fragility function is required for each sequential damage state, and for each group of mutually exclusive or simultaneous damage states (Federal Emergency Management Agency (FEMA), 2012. Seismic performance assessment of buildings, volume 1-methodology. Rep. No. FEMA P-58-1).

Developing Fragility Curves and Predicting Damage Levels

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Develop the fragility curves in all damage levels using 2 parameters.

The demand parameters are different in structural and non-structural elements.

Calculate the possibility in each damage level in percentage

Summarize all results in one table.

Fragility functions are commonly used in performance‐based earthquake engineering for predicting the damage state of a structure subjected to an earthquake. This process often involves estimating the structural damage as a function of structural response, such as the story drift ratio and the peak floor absolute acceleration.

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1. (Ref. Naeim, F., Alimoradi, A., Hagie, S., Comartin, C., 2007. PACT – Performance Assessment Calculation Tool – User Guide for Beta Version 1.0, May 27, 2007. ATC-58 Guidelines for Seismic Performance Assessment of Buildings. Report prepared for Department of Homeland Security, Federal Emergency Management Agency, Washington, DC, United States, 29 pp.)

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