Seismic structural fragilities: Proposals for improved methodology per spectral matching of accelerogram

• Conventional IDA, MSA and the construction of seismic fragilities thereof are reviewed.
• An alternative IDA and/MSA is proposed that is conceptually sound and leads to stable fragility estimate.
• The proposed scheme utilizes spectral matching of real accelerogram or synthetic records compatible to CMS.
• Efficiency of the intensity measures (IMs) are also improved in this proposed approach.

Seismic structural fragilities are often evaluated from structural response computed by Incremental Dynamic Analysis. These fragilities may be unreliable due to inherent limitation in scaling of records. In contrast, unique records with different intensities are employed in Multiple Strip Analysis which is rational, yet computationally intensive. Proposed herein is a conceptually sound method that eliminates these limitations and results in a stable fragility estimate. Real accelerograms are intensified by spectrally matching them to Conditional Mean Spectrum of different return periods. This method has been shown applicable under synthetic records, too. Further, the proposed method is statistically efficient relative to conventional approaches.